This is gfortran.info, produced by makeinfo version 7.1.1 from gfortran.texi. Copyright © 1999-2025 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Funding Free Software", the Front-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled "GNU Free Documentation License". (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development. INFO-DIR-SECTION Software development START-INFO-DIR-ENTRY * gfortran: (gfortran). The GNU Fortran Compiler. END-INFO-DIR-ENTRY This file documents the use and the internals of the GNU Fortran compiler, (‘gfortran’). Published by the Free Software Foundation 51 Franklin Street, Fifth Floor Boston, MA 02110-1301 USA Copyright © 1999-2025 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Funding Free Software", the Front-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled "GNU Free Documentation License". (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.  File: gfortran.info, Node: Top, Next: Introduction, Up: (dir) Introduction ************ This manual documents the use of ‘gfortran’, the GNU Fortran compiler. You can find in this manual how to invoke ‘gfortran’, as well as its features and incompatibilities. * Menu: * Introduction:: Part I: Invoking GNU Fortran * Invoking GNU Fortran:: Command options supported by ‘gfortran’. * Runtime:: Influencing runtime behavior with environment variables. Part II: Language Reference * Compiler Characteristics:: User-visible implementation details. * Extensions:: Language extensions implemented by GNU Fortran. * Mixed-Language Programming:: Interoperability with C * Coarray Programming:: * Intrinsic Procedures:: Intrinsic procedures supported by GNU Fortran. * Intrinsic Modules:: Intrinsic modules supported by GNU Fortran. * Contributing:: How you can help. * Copying:: GNU General Public License says how you can copy and share GNU Fortran. * GNU Free Documentation License:: How you can copy and share this manual. * Funding:: How to help assure continued work for free software. * Option Index:: Index of command line options * Keyword Index:: Index of concepts  File: gfortran.info, Node: Introduction, Next: Invoking GNU Fortran, Prev: Top, Up: Top 1 Introduction ************** * Menu: * About GNU Fortran:: What you should know about the GNU Fortran compiler. * GNU Fortran and GCC:: You can compile Fortran, C, or other programs. * Standards:: Standards supported by GNU Fortran.  File: gfortran.info, Node: About GNU Fortran, Next: GNU Fortran and GCC, Up: Introduction 1.1 About GNU Fortran ===================== The GNU Fortran compiler is the successor to ‘g77’, the Fortran 77 front end included in GCC prior to version 4 (released in 2005). While it is backward-compatible with most ‘g77’ extensions and command-line options, ‘gfortran’ is a completely new implementation designed to support more modern dialects of Fortran. GNU Fortran implements the Fortran 77, 90 and 95 standards completely, most of the Fortran 2003 and 2008 standards, and some features from the 2018 standard. It also implements several extensions including OpenMP and OpenACC support for parallel programming. The GNU Fortran compiler passes the NIST Fortran 77 Test Suite (http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html), and produces acceptable results on the LAPACK Test Suite (https://www.netlib.org/lapack/faq.html). It also provides respectable performance on the Polyhedron Fortran compiler benchmarks (https://polyhedron.com/?page_id=175) and the Livermore Fortran Kernels test (https://www.netlib.org/benchmark/livermore). It has been used to compile a number of large real-world programs, including the HARMONIE and HIRLAM weather forecasting code (http://hirlam.org/) and the Tonto quantum chemistry package (https://github.com/dylan-jayatilaka/tonto); see for an extended list. GNU Fortran provides the following functionality: • Read a program, stored in a file and containing “source code” instructions written in Fortran 77. • Translate the program into instructions a computer can carry out more quickly than it takes to translate the original Fortran instructions. The result after compilation of a program is “machine code”, which is efficiently translated and processed by a machine such as your computer. Humans usually are not as good writing machine code as they are at writing Fortran (or C++, Ada, or Java), because it is easy to make tiny mistakes writing machine code. • Provide information about the reasons why the compiler may be unable to create a binary from the source code, for example if the source code is flawed. The Fortran language standards require that the compiler can point out mistakes in your code. An incorrect usage of the language causes an “error message”. The compiler also attempts to diagnose cases where your program contains a correct usage of the language, but instructs the computer to do something questionable. This kind of diagnostic message is called a “warning message”. • Provide optional information about the translation passes from the source code to machine code. This can help you to find the cause of certain bugs which may not be obvious in the source code, but may be more easily found at a lower level compiler output. It also helps developers to find bugs in the compiler itself. • Provide information in the generated machine code that can make it easier to find bugs in the program (using a debugging tool, called a “debugger”, such as the GNU Debugger ‘gdb’). • Locate and gather machine code already generated to perform actions requested by statements in the program. This machine code is organized into “modules” and is located and “linked” to the user program. The GNU Fortran compiler consists of several components: • A version of the ‘gcc’ command (which also might be installed as the system's ‘cc’ command) that also understands and accepts Fortran source code. The ‘gcc’ command is the “driver” program for all the languages in the GNU Compiler Collection (GCC); With ‘gcc’, you can compile the source code of any language for which a front end is available in GCC. • The ‘gfortran’ command itself, which also might be installed as the system's ‘f95’ command. ‘gfortran’ is just another driver program, but specifically for the Fortran compiler only. The primary difference between the ‘gcc’ and ‘gfortran’ commands is that the latter automatically links the correct libraries to your program. • A collection of run-time libraries. These libraries contain the machine code needed to support capabilities of the Fortran language that are not directly provided by the machine code generated by the ‘gfortran’ compilation phase, such as intrinsic functions and subroutines, and routines for interaction with files and the operating system. • The Fortran compiler itself, (‘f951’). This is the GNU Fortran parser and code generator, linked to and interfaced with the GCC backend library. ‘f951’ "translates" the source code to assembler code. You would typically not use this program directly; instead, the ‘gcc’ or ‘gfortran’ driver programs call it for you.  File: gfortran.info, Node: GNU Fortran and GCC, Next: Standards, Prev: About GNU Fortran, Up: Introduction 1.2 GNU Fortran and GCC ======================= GNU Fortran is a part of GCC, the “GNU Compiler Collection”. GCC consists of a collection of front ends for various languages, which translate the source code into a language-independent form called “GENERIC”. This is then processed by a common middle end which provides optimization, and then passed to one of a collection of back ends which generate code for different computer architectures and operating systems. Functionally, this is implemented with a driver program (‘gcc’) which provides the command-line interface for the compiler. It calls the relevant compiler front-end program (e.g., ‘f951’ for Fortran) for each file in the source code, and then calls the assembler and linker as appropriate to produce the compiled output. In a copy of GCC that has been compiled with Fortran language support enabled, ‘gcc’ recognizes files with ‘.f’, ‘.for’, ‘.ftn’, ‘.f90’, ‘.f95’, ‘.f03’ and ‘.f08’ extensions as Fortran source code, and compiles it accordingly. A ‘gfortran’ driver program is also provided, which is identical to ‘gcc’ except that it automatically links the Fortran runtime libraries into the compiled program. Source files with ‘.f’, ‘.for’, ‘.fpp’, ‘.ftn’, ‘.F’, ‘.FOR’, ‘.FPP’, and ‘.FTN’ extensions are treated as fixed form. Source files with ‘.f90’, ‘.f95’, ‘.f03’, ‘.f08’, ‘.F90’, ‘.F95’, ‘.F03’ and ‘.F08’ extensions are treated as free form. The capitalized versions of either form are run through preprocessing. Source files with the lower case ‘.fpp’ extension are also run through preprocessing. This manual specifically documents the Fortran front end, which handles the programming language's syntax and semantics. The aspects of GCC that relate to the optimization passes and the back-end code generation are documented in the GCC manual; see *note Introduction: (gcc)Top. The two manuals together provide a complete reference for the GNU Fortran compiler.  File: gfortran.info, Node: Standards, Prev: GNU Fortran and GCC, Up: Introduction 1.3 Standards ============= * Menu: * Fortran 95 status:: * Fortran 2003 status:: * Fortran 2008 status:: * Fortran 2018 status:: Fortran is developed by the Working Group 5 of Sub-Committee 22 of the Joint Technical Committee 1 of the International Organization for Standardization and the International Electrotechnical Commission (IEC). This group is known as WG5 (http://www.nag.co.uk/sc22wg5/). Official Fortran standard documents are available for purchase from ISO; a collection of free documents (typically final drafts) are also available on the wiki (https://gcc.gnu.org/wiki/GFortranStandards). The GNU Fortran compiler implements ISO/IEC 1539:1997 (Fortran 95). As such, it can also compile essentially all standard-compliant Fortran 90 and Fortran 77 programs. It also supports the ISO/IEC TR-15581 enhancements to allocatable arrays. GNU Fortran also supports almost all of ISO/IEC 1539-1:2004 (Fortran 2003) and ISO/IEC 1539-1:2010 (Fortran 2008). It has partial support for features introduced in ISO/IEC 1539:2018 (Fortran 2018), the most recent version of the Fortran language standard, including full support for the Technical Specification ‘Further Interoperability of Fortran with C’ (ISO/IEC TS 29113:2012). More details on support for these standards can be found in the following sections of the documentation.  File: gfortran.info, Node: Fortran 95 status, Next: Fortran 2003 status, Up: Standards 1.3.1 Fortran 95 status ----------------------- The Fortran 95 standard specifies in Part 2 (ISO/IEC 1539-2:2000) varying length character strings. While GNU Fortran currently does not support such strings directly, there exist two Fortran implementations for them, which work with GNU Fortran. One can be found at . Deferred-length character strings of Fortran 2003 supports part of the features of ‘ISO_VARYING_STRING’ and should be considered as replacement. (Namely, allocatable or pointers of the type ‘character(len=:)’.) Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines Conditional Compilation, which is not widely used and not directly supported by the GNU Fortran compiler. You can use the program coco to preprocess such files ().  File: gfortran.info, Node: Fortran 2003 status, Next: Fortran 2008 status, Prev: Fortran 95 status, Up: Standards 1.3.2 Fortran 2003 status ------------------------- GNU Fortran implements the Fortran 2003 (ISO/IEC 1539-1:2004) standard except for finalization support, which is incomplete. See the wiki page (https://gcc.gnu.org/wiki/Fortran2003) for a full list of new features introduced by Fortran 2003 and their implementation status.  File: gfortran.info, Node: Fortran 2008 status, Next: Fortran 2018 status, Prev: Fortran 2003 status, Up: Standards 1.3.3 Fortran 2008 status ------------------------- The GNU Fortran compiler supports almost all features of Fortran 2008; the wiki (https://gcc.gnu.org/wiki/Fortran2008Status) has some information about the current implementation status. In particular, the following are not yet supported: • ‘DO CONCURRENT’ and ‘FORALL’ do not recognize a type-spec in the loop header. • The change to permit any constant expression in subscripts and nested implied-do limits in a ‘DATA’ statement has not been implemented.  File: gfortran.info, Node: Fortran 2018 status, Prev: Fortran 2008 status, Up: Standards 1.3.4 Fortran 2018 status ------------------------- Fortran 2018 (ISO/IEC 1539:2018) is the most recent version of the Fortran language standard. GNU Fortran implements some of the new features of this standard: • All Fortran 2018 features derived from ISO/IEC TS 29113:2012, "Further Interoperability of Fortran with C", are supported by GNU Fortran. This includes assumed-type and assumed-rank objects and the ‘SELECT RANK’ construct as well as the parts relating to ‘BIND(C)’ functions. See also *note Further Interoperability of Fortran with C::. • GNU Fortran supports a subset of features derived from ISO/IEC TS 18508:2015, "Additional Parallel Features in Fortran": • The new atomic ADD, CAS, FETCH and ADD/OR/XOR, OR and XOR intrinsics. • The ‘CO_MIN’ and ‘CO_MAX’ and ‘SUM’ reduction intrinsics, and the ‘CO_BROADCAST’ and ‘CO_REDUCE’ intrinsic, except that those do not support polymorphic types or types with allocatable, pointer or polymorphic components. • Events (‘EVENT POST’, ‘EVENT WAIT’, ‘EVENT_QUERY’). • Failed images (‘FAIL IMAGE’, ‘IMAGE_STATUS’, ‘FAILED_IMAGES’, ‘STOPPED_IMAGES’). • An ‘ERROR STOP’ statement is permitted in a ‘PURE’ procedure. • GNU Fortran supports the ‘IMPLICIT NONE’ statement with an ‘implicit-none-spec-list’. • The behavior of the ‘INQUIRE’ statement with the ‘RECL=’ specifier now conforms to Fortran 2018.  File: gfortran.info, Node: Invoking GNU Fortran, Next: Runtime, Prev: Introduction, Up: Top 2 GNU Fortran Command Options ***************************** The ‘gfortran’ command supports all the options supported by the ‘gcc’ command. Only options specific to GNU Fortran are documented here. *Note GCC Command Options: (gcc)Invoking GCC, for information on the non-Fortran-specific aspects of the ‘gcc’ command (and, therefore, the ‘gfortran’ command). All GCC and GNU Fortran options are accepted both by ‘gfortran’ and by ‘gcc’ (as well as any other drivers built at the same time, such as ‘g++’), since adding GNU Fortran to the GCC distribution enables acceptance of GNU Fortran options by all of the relevant drivers. In some cases, options have positive and negative forms; the negative form of ‘-ffoo’ would be ‘-fno-foo’. This manual documents only one of these two forms, whichever one is not the default. * Menu: * Option Summary:: Brief list of all ‘gfortran’ options, without explanations. * Fortran Dialect Options:: Controlling the variant of Fortran language compiled. * Preprocessing Options:: Enable and customize preprocessing. * Error and Warning Options:: How picky should the compiler be? * Debugging Options:: Symbol tables, measurements. * Directory Options:: Where to find module files * Link Options :: Influencing the linking step * Runtime Options:: Influencing runtime behavior * Developer Options:: Printing GNU Fortran specific info, debugging dumps. * Code Gen Options:: Specifying conventions for function calls, data layout and register usage. * Interoperability Options:: Options for interoperability with other languages. * Environment Variables:: Environment variables that affect ‘gfortran’.  File: gfortran.info, Node: Option Summary, Next: Fortran Dialect Options, Up: Invoking GNU Fortran 2.1 Option summary ================== Here is a summary of all the options specific to GNU Fortran, grouped by type. Explanations are in the following sections. _Fortran Language Options_ *Note Options controlling Fortran dialect: Fortran Dialect Options. -fall-intrinsics -fallow-argument-mismatch -fallow-invalid-boz -fbackslash -fcray-pointer -fd-lines-as-code -fd-lines-as-comments -fdec -fdec-char-conversions -fdec-structure -fdec-intrinsic-ints -fdec-static -fdec-math -fdec-include -fdec-format-defaults -fdec-blank-format-item -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 -fdefault-real-10 -fdefault-real-16 -fdollar-ok -ffixed-line-length-N -ffixed-line-length-none -fpad-source -ffree-form -ffree-line-length-N -ffree-line-length-none -fimplicit-none -finteger-4-integer-8 -fmax-identifier-length -fmodule-private -ffixed-form -fno-range-check -fopenacc -fopenmp -fopenmp-allocators -fopenmp-simd -freal-4-real-10 -freal-4-real-16 -freal-4-real-8 -freal-8-real-10 -freal-8-real-16 -freal-8-real-4 -std=STD -ftest-forall-temp -funsigned _Preprocessing Options_ *Note Enable and customize preprocessing: Preprocessing Options. -A-QUESTION[=ANSWER] -AQUESTION=ANSWER -C -CC -DMACRO[=DEFN] -H -P -UMACRO -cpp -dD -dI -dM -dN -dU -fworking-directory -imultilib DIR -iprefix FILE -iquote -isysroot DIR -isystem DIR -nocpp -nostdinc -undef _Error and Warning Options_ *Note Options to request or suppress errors and warnings: Error and Warning Options. -Waliasing -Wall -Wampersand -Warray-bounds -Wc-binding-type -Wcharacter-truncation -Wconversion -Wdo-subscript -Wfunction-elimination -Wimplicit-interface -Wimplicit-procedure -Wintrinsic-shadow -Wuse-without-only -Wintrinsics-std -Wline-truncation -Wno-align-commons -Wno-overwrite-recursive -Wno-tabs -Wreal-q-constant -Wsurprising -Wunderflow -Wunused-parameter -Wrealloc-lhs -Wrealloc-lhs-all -Wfrontend-loop-interchange -Wtarget-lifetime -fmax-errors=N -fsyntax-only -pedantic -pedantic-errors _Debugging Options_ *Note Options for debugging your program: Debugging Options. -fbacktrace -fdebug-aux-vars -ffpe-trap=LIST -ffpe-summary=LIST _Directory Options_ *Note Options for directory search: Directory Options. -IDIR -JDIR -fintrinsic-modules-path DIR _Link Options_ *Note Options for influencing the linking step: Link Options. -static-libgfortran -static-libquadmath _Runtime Options_ *Note Options for influencing runtime behavior: Runtime Options. -fconvert=CONVERSION -fmax-subrecord-length=LENGTH -frecord-marker=LENGTH -fsign-zero _Interoperability Options_ *Note Options for interoperability: Interoperability Options. -fc-prototypes -fc-prototypes-external _Code Generation Options_ *Note Options for code generation conventions: Code Gen Options. -faggressive-function-elimination -fblas-matmul-limit=N -fbounds-check -ftail-call-workaround -ftail-call-workaround=N -fcheck-array-temporaries -fcheck= -fcoarray= -fexternal-blas -ff2c -ffrontend-loop-interchange -ffrontend-optimize -finit-character=N -finit-integer=N -finit-local-zero -finit-derived -finit-logical= -finit-real= -finline-intrinsics[=] -finline-matmul-limit=N -finline-arg-packing -fmax-array-constructor=N -fmax-stack-var-size=N -fno-align-commons -fno-automatic -fno-protect-parens -fno-underscoring -fsecond-underscore -fpack-derived -frealloc-lhs -frecursive -frepack-arrays -fshort-enums -fstack-arrays _Developer Options_ *Note GNU Fortran Developer Options: Developer Options. -fdump-fortran-global -fdump-fortran-optimized -fdump-fortran-original -fdump-parse-tree -save-temps  File: gfortran.info, Node: Fortran Dialect Options, Next: Preprocessing Options, Prev: Option Summary, Up: Invoking GNU Fortran 2.2 Options controlling Fortran dialect ======================================= The following options control the details of the Fortran dialect accepted by the compiler: ‘-ffree-form’ ‘-ffixed-form’ Specify the layout used by the source file. The free form layout was introduced in Fortran 90. Fixed form was traditionally used in older Fortran programs. When neither option is specified, the source form is determined by the file extension. ‘-fall-intrinsics’ This option causes all intrinsic procedures (including the GNU-specific extensions) to be accepted. This can be useful with ‘-std=’ to force standard compliance but get access to the full range of intrinsics available with ‘gfortran’. As a consequence, ‘-Wintrinsics-std’ is ignored and no user-defined procedure with the same name as any intrinsic is called except when it is explicitly declared ‘EXTERNAL’. ‘-fallow-argument-mismatch’ Some code contains calls to external procedures with mismatches between the calls and the procedure definition, or with mismatches between different calls. Such code is nonconforming, and is usually flagged with an error. This options degrades the error to a warning that can only be disabled by disabling all warnings via ‘-w’. Only a single occurrence per argument is flagged by this warning. ‘-fallow-argument-mismatch’ is implied by ‘-std=legacy’. Using this option is _strongly_ discouraged. It is possible to provide standard-conforming code that allows different types of arguments by using an explicit interface and ‘TYPE(*)’. ‘-fallow-invalid-boz’ A BOZ literal constant can occur in a limited number of contexts in standard conforming Fortran. This option degrades an error condition to a warning, and allows a BOZ literal constant to appear where the Fortran standard would otherwise prohibit its use. ‘-fd-lines-as-code’ ‘-fd-lines-as-comments’ Enable special treatment for lines beginning with ‘d’ or ‘D’ in fixed form sources. If the ‘-fd-lines-as-code’ option is given they are treated as if the first column contained a blank. If the ‘-fd-lines-as-comments’ option is given, they are treated as comment lines. ‘-fdec’ DEC compatibility mode. Enables extensions and other features that mimic the default behavior of older compilers (such as DEC). These features are nonstandard and should be avoided at all costs. For details on GNU Fortran's implementation of these extensions see the full documentation. Other flags enabled by this switch are: ‘-fdollar-ok’ ‘-fcray-pointer’ ‘-fdec-char-conversions’ ‘-fdec-structure’ ‘-fdec-intrinsic-ints’ ‘-fdec-static’ ‘-fdec-math’ ‘-fdec-include’ ‘-fdec-blank-format-item’ ‘-fdec-format-defaults’ If ‘-fd-lines-as-code’/‘-fd-lines-as-comments’ are unset, then ‘-fdec’ also sets ‘-fd-lines-as-comments’. ‘-fdec-char-conversions’ Enable the use of character literals in assignments and ‘DATA’ statements for non-character variables. ‘-fdec-structure’ Enable DEC ‘STRUCTURE’ and ‘RECORD’ as well as ‘UNION’, ‘MAP’, and dot ('.') as a member separator (in addition to '%'). This is provided for compatibility only; Fortran 90 derived types should be used instead where possible. ‘-fdec-intrinsic-ints’ Enable B/I/J/K kind variants of existing integer functions (e.g. ‘BIAND’, ‘IIAND’, ‘JIAND’, etc...). For a complete list of intrinsics see *note Intrinsic Procedures::. ‘-fdec-math’ Obsolete flag. The purpose of this option was to enable legacy math intrinsics such as ‘COTAN’ and degree-valued trigonometric functions (e.g. ‘TAND’, ‘ATAND’, etc...) for compatibility with older code. This option is no longer operable. The trigonometric functions are now either part of Fortran 2023 or GNU extensions. ‘-fdec-static’ Enable DEC-style ‘STATIC’ and ‘AUTOMATIC’ attributes to explicitly specify the storage of variables and other objects. ‘-fdec-include’ Enable parsing of ‘INCLUDE’ as a statement in addition to parsing it as ‘INCLUDE’ line. When parsed as ‘INCLUDE’ statement, ‘INCLUDE’ does not have to be on a single line and can use line continuations. ‘-fdec-format-defaults’ Enable format specifiers ‘F’, ‘G’ and ‘I’ to be used without width specifiers; default widths are used instead. ‘-fdec-blank-format-item’ Enable a blank format item at the end of a format specification i.e. nothing following the final comma. ‘-fdollar-ok’ Allow ‘$’ as a valid non-first character in a symbol name. Symbols that start with ‘$’ are rejected since it is unclear which rules to apply to implicit typing as different vendors implement different rules. Using ‘$’ in ‘IMPLICIT’ statements is also rejected. ‘-fbackslash’ Change the interpretation of backslashes in string literals from a single backslash character to "C-style" escape characters. The following combinations are expanded: ‘\a’, ‘\b’, ‘\f’, ‘\n’, ‘\r’, ‘\t’, ‘\v’, ‘\\’, and ‘\0’ to the ASCII characters alert, backspace, form feed, newline, carriage return, horizontal tab, vertical tab, backslash, and NUL, respectively. Additionally, ‘\xNN’, ‘\uNNNN’ and ‘\UNNNNNNNN’ (where each N is a hexadecimal digit) are translated into the Unicode characters corresponding to the specified code points. All other combinations of a character preceded by ‘\’ are unexpanded. ‘-fmodule-private’ Set the default accessibility of module entities to ‘PRIVATE’. Use-associated entities are not accessible unless they are explicitly declared as ‘PUBLIC’. ‘-ffixed-line-length-N’ Set column after which characters are ignored in typical fixed-form lines in the source file, and, unless ‘-fno-pad-source’, through which spaces are assumed (as if padded to that length) after the ends of short fixed-form lines. Popular values for N include 72 (the standard and the default), 80 (card image), and 132 (corresponding to "extended-source" options in some popular compilers). N may also be ‘none’, meaning that the entire line is meaningful and that continued character constants never have implicit spaces appended to them to fill out the line. ‘-ffixed-line-length-0’ means the same thing as ‘-ffixed-line-length-none’. ‘-fno-pad-source’ By default fixed-form lines have spaces assumed (as if padded to that length) after the ends of short fixed-form lines. This is not done either if ‘-ffixed-line-length-0’, ‘-ffixed-line-length-none’ or if ‘-fno-pad-source’ option is used. With any of those options continued character constants never have implicit spaces appended to them to fill out the line. ‘-ffree-line-length-N’ Set column after which characters are ignored in typical free-form lines in the source file. The default value is 132. N may be ‘none’, meaning that the entire line is meaningful. ‘-ffree-line-length-0’ means the same thing as ‘-ffree-line-length-none’. ‘-fmax-identifier-length=N’ Specify the maximum allowed identifier length. Typical values are 31 (Fortran 95) and 63 (Fortran 2003 and later). ‘-fimplicit-none’ Specify that no implicit typing is allowed, unless overridden by explicit ‘IMPLICIT’ statements. This is the equivalent of adding ‘implicit none’ to the start of every procedure. ‘-fcray-pointer’ Enable the Cray pointer extension, which provides C-like pointer functionality. ‘-fopenacc’ Enable handling of OpenACC directives ‘!$acc’ in free-form Fortran and ‘!$acc’, ‘c$acc’ and ‘*$acc’ in fixed-form Fortran. When ‘-fopenacc’ is specified, the compiler generates accelerated code according to the OpenACC Application Programming Interface v2.6 . This option implies ‘-pthread’, and thus is only supported on targets that have support for ‘-pthread’. The option ‘-fopenacc’ implies ‘-frecursive’. ‘-fopenmp’ Enable handling of OpenMP directives ‘!$omp’ in Fortran. It additionally enables the conditional compilation sentinel ‘!$’ in Fortran. In fixed source form Fortran, the sentinels can also start with ‘c’ or ‘*’. When ‘-fopenmp’ is specified, the compiler generates parallel code according to the OpenMP Application Program Interface v4.5 . This option implies ‘-pthread’, and thus is only supported on targets that have support for ‘-pthread’. ‘-fopenmp’ implies ‘-fopenmp-simd’ and ‘-frecursive’. ‘-fopenmp-allocators’ Enables handling of allocation, reallocation and deallocation of Fortran allocatable and pointer variables that are allocated using the ‘!$omp allocators’ and ‘!$omp allocate’ constructs. Files containing either directive have to be compiled with this option in addition to ‘-fopenmp’. Additionally, all files that might deallocate or reallocate a variable that has been allocated with an OpenMP allocator have to be compiled with this option. This includes intrinsic assignment to allocatable variables when reallocation may occur and deallocation due to either of the following: end of scope, explicit deallocation, ‘intent(out)’, deallocation of allocatable components etc. Files not changing the allocation status or only for components of a derived type that have not been allocated using those two directives do not need to be compiled with this option. Nor do files that handle such variables after they have been deallocated or allocated by the normal Fortran allocator. ‘-fopenmp-simd’ Enable handling of OpenMP's ‘simd’, ‘declare simd’, ‘declare reduction’, ‘assume’, ‘ordered’, ‘scan’ and ‘loop’ directive, and of combined or composite directives with ‘simd’ as constituent with ‘!$omp’ in Fortran. It additionally enables the conditional compilation sentinel ‘!$’ in Fortran. In fixed source form Fortran, the sentinels can also start with ‘c’ or ‘*’. Other OpenMP directives are ignored. Unless ‘-fopenmp’ is additionally specified, the ‘loop’ region binds to the current task region, independent of the specified ‘bind’ clause. ‘-fno-range-check’ Disable range checking on results of simplification of constant expressions during compilation. For example, GNU Fortran gives an error at compile time when simplifying ‘a = 1. / 0’. With this option, no error is given and ‘a’ is assigned the value ‘+Infinity’. If an expression evaluates to a value outside of the relevant range of [‘-HUGE()’:‘HUGE()’], then the expression is replaced by ‘-Inf’ or ‘+Inf’ as appropriate. Similarly, ‘DATA i/Z'FFFFFFFF'/’ results in an integer overflow on most systems, but with ‘-fno-range-check’ the value "wraps around" and ‘i’ is initialized to -1 instead. ‘-fdefault-integer-8’ Set the default integer and logical types to an 8 byte wide type. This option also affects the kind of integer constants like ‘42’. Unlike ‘-finteger-4-integer-8’, it does not promote variables with explicit kind declaration. ‘-fdefault-real-8’ Set the default real type to an 8 byte wide type. This option also affects the kind of non-double real constants like ‘1.0’. This option promotes the default width of ‘DOUBLE PRECISION’ and double real constants like ‘1.d0’ to 16 bytes if possible. If ‘-fdefault-double-8’ is given along with ‘fdefault-real-8’, ‘DOUBLE PRECISION’ and double real constants are not promoted. Unlike ‘-freal-4-real-8’, ‘fdefault-real-8’ does not promote variables with explicit kind declarations. ‘-fdefault-real-10’ Set the default real type to an 10 byte wide type. This option also affects the kind of non-double real constants like ‘1.0’. This option promotes the default width of ‘DOUBLE PRECISION’ and double real constants like ‘1.d0’ to 16 bytes if possible. If ‘-fdefault-double-8’ is given along with ‘fdefault-real-10’, ‘DOUBLE PRECISION’ and double real constants are not promoted. Unlike ‘-freal-4-real-10’, ‘fdefault-real-10’ does not promote variables with explicit kind declarations. ‘-fdefault-real-16’ Set the default real type to an 16 byte wide type. This option also affects the kind of non-double real constants like ‘1.0’. This option promotes the default width of ‘DOUBLE PRECISION’ and double real constants like ‘1.d0’ to 16 bytes if possible. If ‘-fdefault-double-8’ is given along with ‘fdefault-real-16’, ‘DOUBLE PRECISION’ and double real constants are not promoted. Unlike ‘-freal-4-real-16’, ‘fdefault-real-16’ does not promote variables with explicit kind declarations. ‘-fdefault-double-8’ Set the ‘DOUBLE PRECISION’ type and double real constants like ‘1.d0’ to an 8 byte wide type. Do nothing if this is already the default. This option prevents ‘-fdefault-real-8’, ‘-fdefault-real-10’, and ‘-fdefault-real-16’, from promoting ‘DOUBLE PRECISION’ and double real constants like ‘1.d0’ to 16 bytes. ‘-finteger-4-integer-8’ Promote all ‘INTEGER(KIND=4)’ entities to an ‘INTEGER(KIND=8)’ entities. If ‘KIND=8’ is unavailable, then an error is issued. This option should be used with care and may not be suitable for your codes. Areas of possible concern include calls to external procedures, alignment in ‘EQUIVALENCE’ and/or ‘COMMON’, generic interfaces, BOZ literal constant conversion, and I/O. Inspection of the intermediate representation of the translated Fortran code, produced by ‘-fdump-tree-original’, is suggested. ‘-freal-4-real-8’ ‘-freal-4-real-10’ ‘-freal-4-real-16’ ‘-freal-8-real-4’ ‘-freal-8-real-10’ ‘-freal-8-real-16’ Promote all ‘REAL(KIND=M)’ entities to ‘REAL(KIND=N)’ entities. If ‘REAL(KIND=N)’ is unavailable, then an error is issued. The ‘-freal-4-’ flags also affect the default real kind and the ‘-freal-8-’ flags also the double-precision real kind. All other real-kind types are unaffected by this option. The promotion is also applied to real literal constants of default and double-precision kind and a specified kind number of 4 or 8, respectively. However, ‘-fdefault-real-8’, ‘-fdefault-real-10’, ‘-fdefault-real-10’, and ‘-fdefault-double-8’ take precedence for the default and double-precision real kinds, both for real literal constants and for declarations without a kind number. Note that for ‘REAL(KIND=KIND(1.0))’ the literal may get promoted and then the result may get promoted again. These options should be used with care and may not be suitable for your codes. Areas of possible concern include calls to external procedures, alignment in ‘EQUIVALENCE’ and/or ‘COMMON’, generic interfaces, BOZ literal constant conversion, and I/O and calls to intrinsic procedures when passing a value to the ‘kind=’ dummy argument. Inspection of the intermediate representation of the translated Fortran code, produced by ‘-fdump-fortran-original’ or ‘-fdump-tree-original’, is suggested. ‘-std=STD’ Specify the standard to which the program is expected to conform, which may be one of ‘f95’, ‘f2003’, ‘f2008’, ‘f2018’, ‘f2023’, ‘gnu’, or ‘legacy’. The default value for STD is ‘gnu’, which specifies a superset of the latest Fortran standard that includes all of the extensions supported by GNU Fortran, although warnings are given for obsolete extensions not recommended for use in new code. The ‘legacy’ value is equivalent but without the warnings for obsolete extensions, and may be useful for old nonstandard programs. The ‘f95’, ‘f2003’, ‘f2008’, ‘f2018’, and ‘f2023’ values specify strict conformance to the Fortran 95, Fortran 2003, Fortran 2008, Fortran 2018 and Fortran 2023 standards, respectively; errors are given for all extensions beyond the relevant language standard, and warnings are given for the Fortran 77 features that are permitted but obsolescent in later standards. The deprecated option ‘-std=f2008ts’ acts as an alias for ‘-std=f2018’. It is only present for backwards compatibility with earlier gfortran versions and should not be used any more. ‘-std=f202y’ acts as an alias for ‘-std=f2023’ and enables proposed features for testing Fortran 202y. As the Fortran 202y standard develops, implementation might change or the experimental new features might be removed. ‘-ftest-forall-temp’ Enhance test coverage by forcing most forall assignments to use temporary. ‘-funsigned’ Allow the experimental unsigned extension.  File: gfortran.info, Node: Preprocessing Options, Next: Error and Warning Options, Prev: Fortran Dialect Options, Up: Invoking GNU Fortran 2.3 Enable and customize preprocessing ====================================== Many Fortran compilers including GNU Fortran allow passing the source code through a C preprocessor (CPP; sometimes also called the Fortran preprocessor, FPP) to allow for conditional compilation. In the case of GNU Fortran, this is the GNU C Preprocessor in the traditional mode. On systems with case-preserving file names, the preprocessor is automatically invoked if the filename extension is ‘.F’, ‘.FOR’, ‘.FTN’, ‘.fpp’, ‘.FPP’, ‘.F90’, ‘.F95’, ‘.F03’ or ‘.F08’. To manually invoke the preprocessor on any file, use ‘-cpp’, to disable preprocessing on files where the preprocessor is run automatically, use ‘-nocpp’. If a preprocessed file includes another file with the Fortran ‘INCLUDE’ statement, the included file is not preprocessed. To preprocess included files, use the equivalent preprocessor statement ‘#include’. If GNU Fortran invokes the preprocessor, ‘__GFORTRAN__’ is defined. The macros ‘__GNUC__’, ‘__GNUC_MINOR__’ and ‘__GNUC_PATCHLEVEL__’ can be used to determine the version of the compiler. See *note Overview: (cpp)Top. for details. GNU Fortran supports a number of ‘INTEGER’ and ‘REAL’ kind types in additional to the kind types required by the Fortran standard. The availability of any given kind type is architecture dependent. The following predefined preprocessor macros can be used to conditionally include code for these additional kind types: ‘__GFC_INT_1__’, ‘__GFC_INT_2__’, ‘__GFC_INT_8__’, ‘__GFC_INT_16__’, ‘__GFC_REAL_10__’, and ‘__GFC_REAL_16__’. While CPP is the de facto standard for preprocessing Fortran code, Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines Conditional Compilation, which is not widely used and not directly supported by the GNU Fortran compiler. The following options control preprocessing of Fortran code: ‘-cpp’ ‘-nocpp’ Enable preprocessing. The preprocessor is automatically invoked if the file extension is ‘.fpp’, ‘.FPP’, ‘.F’, ‘.FOR’, ‘.FTN’, ‘.F90’, ‘.F95’, ‘.F03’ or ‘.F08’. Use this option to manually enable preprocessing of any kind of Fortran file. To disable preprocessing of files with any of the above listed extensions, use the negative form: ‘-nocpp’. The preprocessor is run in traditional mode. Any restrictions of the file format, especially the limits on line length, apply for preprocessed output as well, so it might be advisable to use the ‘-ffree-line-length-none’ or ‘-ffixed-line-length-none’ options. ‘-dM’ Instead of the normal output, generate a list of ‘'#define'’ directives for all the macros defined during the execution of the preprocessor, including predefined macros. This gives you a way of finding out what is predefined in your version of the preprocessor. Assuming you have no file ‘foo.f90’, the command touch foo.f90; gfortran -cpp -E -dM foo.f90 shows all the predefined macros. ‘-dD’ Like ‘-dM’ except in two respects: it does not include the predefined macros, and it outputs both the ‘#define’ directives and the result of preprocessing. Both kinds of output go to the standard output file. ‘-dN’ Like ‘-dD’, but emit only the macro names, not their expansions. ‘-dU’ Like ‘dD’ except that only macros that are expanded, or whose definedness is tested in preprocessor directives, are output; the output is delayed until the use or test of the macro; and ‘'#undef'’ directives are also output for macros tested but undefined at the time. ‘-dI’ Output ‘'#include'’ directives in addition to the result of preprocessing. ‘-fworking-directory’ Enable generation of linemarkers in the preprocessor output that let the compiler know the current working directory at the time of preprocessing. When this option is enabled, the preprocessor emits, after the initial linemarker, a second linemarker with the current working directory followed by two slashes. GCC uses this directory, when it is present in the preprocessed input, as the directory emitted as the current working directory in some debugging information formats. This option is implicitly enabled if debugging information is enabled, but this can be inhibited with the negated form ‘-fno-working-directory’. If the ‘-P’ flag is present in the command line, this option has no effect, since no ‘#line’ directives are emitted whatsoever. ‘-idirafter DIR’ Search DIR for include files, but do it after all directories specified with ‘-I’ and the standard system directories have been exhausted. DIR is treated as a system include directory. If dir begins with ‘=’, then the ‘=’ is replaced by the sysroot prefix; see ‘--sysroot’ and ‘-isysroot’. ‘-imultilib DIR’ Use DIR as a subdirectory of the directory containing target-specific C++ headers. ‘-iprefix PREFIX’ Specify PREFIX as the prefix for subsequent ‘-iwithprefix’ options. If the PREFIX represents a directory, you should include the final ‘'/'’. ‘-isysroot DIR’ This option is like the ‘--sysroot’ option, but applies only to header files. See the ‘--sysroot’ option for more information. ‘-iquote DIR’ Search DIR only for header files requested with ‘#include "file"’; they are not searched for ‘#include ’, before all directories specified by ‘-I’ and before the standard system directories. If DIR begins with ‘=’, then the ‘=’ is replaced by the sysroot prefix; see ‘--sysroot’ and ‘-isysroot’. ‘-isystem DIR’ Search DIR for header files, after all directories specified by ‘-I’ but before the standard system directories. Mark it as a system directory, so that it gets the same special treatment as is applied to the standard system directories. If DIR begins with ‘=’, then the ‘=’ is replaced by the sysroot prefix; see ‘--sysroot’ and ‘-isysroot’. ‘-nostdinc’ Do not search the standard system directories for header files. Only the directories you have specified with ‘-I’ options (and the directory of the current file, if appropriate) are searched. ‘-undef’ Do not predefine any system-specific or GCC-specific macros. The standard predefined macros remain defined. ‘-APREDICATE=ANSWER’ Make an assertion with the predicate PREDICATE and answer ANSWER. This form is preferred to the older form -A predicate(answer), which is still supported, because it does not use shell special characters. ‘-A-PREDICATE=ANSWER’ Cancel an assertion with the predicate PREDICATE and answer ANSWER. ‘-C’ Do not discard comments. All comments are passed through to the output file, except for comments in processed directives, which are deleted along with the directive. You should be prepared for side effects when using ‘-C’; it causes the preprocessor to treat comments as tokens in their own right. For example, comments appearing at the start of what would be a directive line have the effect of turning that line into an ordinary source line, since the first token on the line is no longer a ‘'#'’. Warning: this currently handles C-Style comments only. The preprocessor does not yet recognize Fortran-style comments. ‘-CC’ Do not discard comments, including during macro expansion. This is like ‘-C’, except that comments contained within macros are also passed through to the output file where the macro is expanded. In addition to the side-effects of the ‘-C’ option, the ‘-CC’ option causes all C++-style comments inside a macro to be converted to C-style comments. This is to prevent later use of that macro from inadvertently commenting out the remainder of the source line. The ‘-CC’ option is generally used to support lint comments. Warning: this currently handles C- and C++-Style comments only. The preprocessor does not yet recognize Fortran-style comments. ‘-DNAME’ Predefine name as a macro, with definition ‘1’. ‘-DNAME=DEFINITION’ The contents of DEFINITION are tokenized and processed as if they appeared during translation phase three in a ‘'#define'’ directive. In particular, the definition is truncated by embedded newline characters. If you are invoking the preprocessor from a shell or shell-like program you may need to use the shell's quoting syntax to protect characters such as spaces that have a meaning in the shell syntax. If you wish to define a function-like macro on the command line, write its argument list with surrounding parentheses before the equals sign (if any). Parentheses are meaningful to most shells, so you need to quote the option. With sh and csh, ‘-D'name(args...)=definition'’ works. ‘-D’ and ‘-U’ options are processed in the order they are given on the command line. All -imacros file and -include file options are processed after all -D and -U options. ‘-H’ Print the name of each header file used, in addition to other normal activities. Each name is indented to show how deep in the ‘'#include'’ stack it is. ‘-P’ Inhibit generation of linemarkers in the output from the preprocessor. This might be useful when running the preprocessor on something that is not C code, and is sent to a program that might be confused by the linemarkers. ‘-UNAME’ Cancel any previous definition of NAME, either built in or provided with a ‘-D’ option.  File: gfortran.info, Node: Error and Warning Options, Next: Debugging Options, Prev: Preprocessing Options, Up: Invoking GNU Fortran 2.4 Options to request or suppress errors and warnings ====================================================== Errors are diagnostic messages that report that the GNU Fortran compiler cannot compile the relevant piece of source code. The compiler continues to process the program in an attempt to report further errors to aid in debugging, but does not produce any compiled output. Warnings are diagnostic messages that report constructions that are not inherently erroneous but that are risky or suggest there is likely to be a bug in the program. Unless ‘-Werror’ is specified, they do not prevent compilation of the program. You can request many specific warnings with options beginning ‘-W’, for example ‘-Wimplicit’ to request warnings on implicit declarations. Each of these specific warning options also has a negative form beginning ‘-Wno-’ to turn off warnings; for example, ‘-Wno-implicit’. This manual lists only one of the two forms, whichever is not the default. These options control the amount and kinds of errors and warnings produced by GNU Fortran: ‘-fmax-errors=N’ Limits the maximum number of error messages to N, at which point GNU Fortran bails out rather than attempting to continue processing the source code. If N is 0, there is no limit on the number of error messages produced. ‘-fsyntax-only’ Check the code for syntax errors, but do not actually compile it. This generates module files for each module present in the code, but no other output file. ‘-Wpedantic’ ‘-pedantic’ Issue warnings for uses of extensions to Fortran. ‘-pedantic’ also applies to C-language constructs where they occur in GNU Fortran source files, such as use of ‘\e’ in a character constant within a directive like ‘#include’. Valid Fortran programs should compile properly with or without this option. However, without this option, certain GNU extensions and traditional Fortran features are supported as well. With this option, many of them are rejected. Some users try to use ‘-pedantic’ to check programs for conformance. They soon find that it does not do quite what they want--it finds some nonstandard practices, but not all. However, improvements to GNU Fortran in this area are welcome. This should be used in conjunction with ‘-std=f95’, ‘-std=f2003’, ‘-std=f2008’, ‘-std=f2018’ or ‘-std=f2023’. ‘-pedantic-errors’ Like ‘-pedantic’, except that errors are produced rather than warnings. ‘-Wall’ Enables commonly used warning options pertaining to usage that we recommend avoiding and that we believe are easy to avoid. This currently includes ‘-Waliasing’, ‘-Wampersand’, ‘-Wconversion’, ‘-Wsurprising’, ‘-Wc-binding-type’, ‘-Wintrinsics-std’, ‘-Wtabs’, ‘-Wintrinsic-shadow’, ‘-Wline-truncation’, ‘-Wtarget-lifetime’, ‘-Winteger-division’, ‘-Wreal-q-constant’, ‘-Wunused’ and ‘-Wundefined-do-loop’. ‘-Waliasing’ Warn about possible aliasing of dummy arguments. Specifically, it warns if the same actual argument is associated with a dummy argument with ‘INTENT(IN)’ and a dummy argument with ‘INTENT(OUT)’ in a call with an explicit interface. The following example triggers the warning. interface subroutine bar(a,b) integer, intent(in) :: a integer, intent(out) :: b end subroutine end interface integer :: a call bar(a,a) ‘-Wampersand’ Warn about missing ampersand in continued character constants. The warning is given with ‘-Wampersand’, ‘-pedantic’, ‘-std=f95’, ‘-std=f2003’, ‘-std=f2008’, ‘-std=f2018’ and ‘-std=f2023’. Note: With no ampersand given in a continued character constant, GNU Fortran assumes continuation at the first non-comment, non-whitespace character after the ampersand that initiated the continuation. ‘-Warray-temporaries’ Warn about array temporaries generated by the compiler. The information generated by this warning is sometimes useful in optimization, in order to avoid such temporaries. ‘-Wc-binding-type’ Warn if the a variable might not be C interoperable. In particular, warn if the variable has been declared using an intrinsic type with default kind instead of using a kind parameter defined for C interoperability in the intrinsic ‘ISO_C_Binding’ module. This option is implied by ‘-Wall’. ‘-Wcharacter-truncation’ Warn when a character assignment truncates the assigned string. ‘-Wline-truncation’ Warn when a source code line is truncated. This option is implied by ‘-Wall’. For free-form source code, the default is ‘-Werror=line-truncation’ such that truncations are reported as error. ‘-Wconversion’ Warn about implicit conversions that are likely to change the value of the expression after conversion. Implied by ‘-Wall’. ‘-Wconversion-extra’ Warn about implicit conversions between different types and kinds. This option does _not_ imply ‘-Wconversion’. ‘-Wexternal-argument-mismatch’ Warn about argument mismatches for dummy external procedures. This is implied by ‘-fc-prototypes-external’ because generation of a valid C23 interface is not possible in such a case. Also implied by ‘-Wall’. ‘-Wextra’ Enables some warning options for usages of language features that may be problematic. This currently includes ‘-Wcompare-reals’, ‘-Wunused-parameter’ and ‘-Wdo-subscript’. ‘-Wfrontend-loop-interchange’ Warn when using ‘-ffrontend-loop-interchange’ for performing loop interchanges. ‘-Wimplicit-interface’ Warn if a procedure is called without an explicit interface. Note this only checks that an explicit interface is present. It does not check that the declared interfaces are consistent across program units. ‘-Wimplicit-procedure’ Warn if a procedure is called that has neither an explicit interface nor has been declared as ‘EXTERNAL’. ‘-Winteger-division’ Warn if a constant integer division truncates its result. As an example, 3/5 evaluates to 0. ‘-Wintrinsics-std’ Warn if ‘gfortran’ finds a procedure named like an intrinsic not available in the currently selected standard (with ‘-std’) and treats it as ‘EXTERNAL’ procedure because of this. ‘-fall-intrinsics’ can be used to never trigger this behavior and always link to the intrinsic regardless of the selected standard. ‘-Wno-overwrite-recursive’ Do not warn when ‘-fno-automatic’ is used with ‘-frecursive’. Recursion is broken if the relevant local variables do not have the attribute ‘AUTOMATIC’ explicitly declared. This option can be used to suppress the warning when it is known that recursion is not broken. Useful for build environments that use ‘-Werror’. ‘-Wreal-q-constant’ Produce a warning if a real-literal-constant contains a ‘q’ exponent-letter. ‘-Wsurprising’ Produce a warning when "suspicious" code constructs are encountered. While technically legal these usually indicate that an error has been made. This currently produces a warning under the following circumstances: • An ‘INTEGER’-typed ‘SELECT CASE’ construct has a ‘CASE’ that can never be matched as its lower value is greater than its upper value. • A ‘LOGICAL’-typed ‘SELECT CASE’ construct has three ‘CASE’ statements. • A ‘TRANSFER’ specifies a source that is shorter than the destination. • The type of a function result is declared more than once with the same type. If ‘-pedantic’ or standard-conforming mode is enabled, this is an error. • A ‘CHARACTER’ variable is declared with negative length. • With ‘-fopenmp’, for fixed-form source code, when an ‘omx’ vendor-extension sentinel is encountered. (The equivalent ‘ompx’, used in free-form source code, is diagnosed by default.) ‘-Wtabs’ By default, tabs are accepted as whitespace, but tabs are not members of the Fortran Character Set. For continuation lines, a tab followed by a digit between 1 and 9 is supported. ‘-Wtabs’ causes a warning to be issued if a tab is encountered. Note, ‘-Wtabs’ is active for ‘-pedantic’, ‘-std=f95’, ‘-std=f2003’, ‘-std=f2008’, ‘-std=f2018’, ‘-std=f2023’ and ‘-Wall’. ‘-Wundefined-do-loop’ Warn if a ‘DO’ loop with step either 1 or -1 yields an underflow or an overflow during iteration of an induction variable of the loop. This option is implied by ‘-Wall’. ‘-Wunderflow’ Produce a warning when numerical constant expressions that yield an underflow are encountered during compilation. Enabled by default. ‘-Wintrinsic-shadow’ Warn if a user-defined procedure or module procedure has the same name as an intrinsic; in this case, an explicit interface or ‘EXTERNAL’ or ‘INTRINSIC’ declaration might be needed to get calls later resolved to the desired intrinsic/procedure. This option is implied by ‘-Wall’. ‘-Wuse-without-only’ Warn if a ‘USE’ statement has no ‘ONLY’ qualifier and thus implicitly imports all public entities of the used module. ‘-Wunused-dummy-argument’ Warn about unused dummy arguments. This option is implied by ‘-Wall’. ‘-Wunused-parameter’ Contrary to ‘gcc’'s meaning of ‘-Wunused-parameter’, ‘gfortran’'s implementation of this option does not warn about unused dummy arguments (see ‘-Wunused-dummy-argument’), but about unused ‘PARAMETER’ values. ‘-Wunused-parameter’ is implied by ‘-Wextra’ if also ‘-Wunused’ or ‘-Wall’ is used. ‘-Walign-commons’ By default, ‘gfortran’ warns about any occasion of variables being padded for proper alignment inside a ‘COMMON’ block. This warning can be turned off via ‘-Wno-align-commons’. See also ‘-falign-commons’. ‘-Wfunction-elimination’ Warn if any calls to impure functions are eliminated by the optimizations enabled by the ‘-ffrontend-optimize’ option. This option is implied by ‘-Wextra’. ‘-Wrealloc-lhs’ Warn when the compiler might insert code to for allocation or reallocation of an allocatable array variable of intrinsic type in intrinsic assignments. In hot loops, the Fortran 2003 reallocation feature may reduce the performance. If the array is already allocated with the correct shape, consider using a whole-array array-spec (e.g. ‘(:,:,:)’) for the variable on the left-hand side to prevent the reallocation check. Note that in some cases the warning is shown, even if the compiler optimizes reallocation checks away. For instance, when the right-hand side contains the same variable multiplied by a scalar. See also ‘-frealloc-lhs’. ‘-Wrealloc-lhs-all’ Warn when the compiler inserts code to for allocation or reallocation of an allocatable variable; this includes scalars and derived types. ‘-Wcompare-reals’ Warn when comparing real or complex types for equality or inequality. This option is implied by ‘-Wextra’. ‘-Wtarget-lifetime’ Warn if the pointer in a pointer assignment might be longer than the its target. This option is implied by ‘-Wall’. ‘-Wzerotrip’ Warn if a ‘DO’ loop is known to execute zero times at compile time. This option is implied by ‘-Wall’. ‘-Wdo-subscript’ Warn if an array subscript inside a ‘DO’ loop could lead to an out-of-bounds access even if the compiler cannot prove that the statement is actually executed, in cases like real a(3) do i=1,4 if (condition(i)) then a(i) = 1.2 end if end do This option is implied by ‘-Wextra’. ‘-Werror’ Turns all warnings into errors. *Note Options to Request or Suppress Errors and Warnings: (gcc)Warning Options, for information on more options offered by the back end shared by ‘gfortran’, ‘gcc’ and other GNU compilers. Some of these have no effect when compiling programs written in Fortran.  File: gfortran.info, Node: Debugging Options, Next: Directory Options, Prev: Error and Warning Options, Up: Invoking GNU Fortran 2.5 Options for debugging your program ====================================== GNU Fortran has various special options that are used for debugging your program. ‘-fdebug-aux-vars’ Renames internal variables created by the gfortran front end and makes them accessible to a debugger. The name of the internal variables then start with uppercase letters followed by an underscore. This option is useful for debugging the compiler's code generation together with ‘-fdump-tree-original’ and enabling debugging of the executable program by using ‘-g’ or ‘-ggdb3’. ‘-ffpe-trap=LIST’ Specify a list of floating point exception traps to enable. On most systems, if a floating point exception occurs and the trap for that exception is enabled, a ‘SIGFPE’ signal is sent and the program being aborted, producing a core file useful for debugging. LIST is a (possibly empty) comma-separated list of either ‘none’ (to clear the set of exceptions to be trapped), or of the following exceptions: ‘invalid’ (invalid floating point operation, such as ‘SQRT(-1.0)’), ‘zero’ (division by zero), ‘overflow’ (overflow in a floating point operation), ‘underflow’ (underflow in a floating point operation), ‘inexact’ (loss of precision during operation), and ‘denormal’ (operation performed on a denormal value). The first five exceptions correspond to the five IEEE 754 exceptions, whereas the last one (‘denormal’) is not part of the IEEE 754 standard but is available on some common architectures such as x86. The first three exceptions (‘invalid’, ‘zero’, and ‘overflow’) often indicate serious errors, and unless the program has provisions for dealing with these exceptions, enabling traps for these three exceptions is probably a good idea. If the option is used more than once in the command line, the lists are joined: '‘ffpe-trap=’LIST1 ‘ffpe-trap=’LIST2' is equivalent to ‘ffpe-trap=’LIST1,LIST2. Note that once enabled an exception cannot be disabled (no negative form), except by clearing all traps by specifying ‘none’. Many, if not most, floating point operations incur loss of precision due to rounding, and hence the ‘ffpe-trap=inexact’ is likely to be uninteresting in practice. By default no exception traps are enabled. ‘-ffpe-summary=LIST’ Specify a list of floating-point exceptions, whose flag status is printed to ‘ERROR_UNIT’ when invoking ‘STOP’ and ‘ERROR STOP’. LIST can be either ‘none’, ‘all’ or a comma-separated list of the following exceptions: ‘invalid’, ‘zero’, ‘overflow’, ‘underflow’, ‘inexact’ and ‘denormal’. (See ‘-ffpe-trap’ for a description of the exceptions.) If the option is used more than once in the command line, only the last one is used. By default, a summary for all exceptions but ‘inexact’ is shown. ‘-fno-backtrace’ When a serious runtime error is encountered or a deadly signal is emitted (segmentation fault, illegal instruction, bus error, floating-point exception, and the other POSIX signals that have the action ‘core’), the Fortran runtime library tries to output a backtrace of the error. ‘-fno-backtrace’ disables the backtrace generation. This option only has influence for compilation of the Fortran main program. *Note Options for Debugging Your Program or GCC: (gcc)Debugging Options, for more information on debugging options.  File: gfortran.info, Node: Directory Options, Next: Link Options, Prev: Debugging Options, Up: Invoking GNU Fortran 2.6 Options for directory search ================================ These options affect how GNU Fortran searches for files specified by the ‘INCLUDE’ directive and where it searches for previously compiled modules. It also affects the search paths used by ‘cpp’ when used to preprocess Fortran source. ‘-IDIR’ These affect interpretation of the ‘INCLUDE’ directive (as well as of the ‘#include’ directive of the ‘cpp’ preprocessor). Also note that the general behavior of ‘-I’ and ‘INCLUDE’ is pretty much the same as of ‘-I’ with ‘#include’ in the ‘cpp’ preprocessor, with regard to looking for ‘header.gcc’ files and other such things. This path is also used to search for ‘.mod’ files when previously compiled modules are required by a ‘USE’ statement. *Note Options for Directory Search: (gcc)Directory Options, for information on the ‘-I’ option. ‘-JDIR’ This option specifies where to put ‘.mod’ files for compiled modules. It is also added to the list of directories to searched by an ‘USE’ statement. The default is the current directory. ‘-fintrinsic-modules-path DIR’ This option specifies the location of pre-compiled intrinsic modules, if they are not in the default location expected by the compiler.  File: gfortran.info, Node: Link Options, Next: Runtime Options, Prev: Directory Options, Up: Invoking GNU Fortran 2.7 Influencing the linking step ================================ These options come into play when the compiler links object files into an executable output file. They are meaningless if the compiler is not doing a link step. ‘-static-libgfortran’ On systems that provide ‘libgfortran’ as a shared and a static library, this option forces the use of the static version. If no shared version of ‘libgfortran’ was built when the compiler was configured, this option has no effect. ‘-static-libquadmath’ On systems that provide ‘libquadmath’ as a shared and a static library, this option forces the use of the static version. If no shared version of ‘libquadmath’ was built when the compiler was configured, this option has no effect. Please note that the ‘libquadmath’ runtime library is licensed under the GNU Lesser General Public License (LGPL), and linking it statically introduces requirements when redistributing the resulting binaries.  File: gfortran.info, Node: Runtime Options, Next: Developer Options, Prev: Link Options, Up: Invoking GNU Fortran 2.8 Influencing runtime behavior ================================ These options affect the runtime behavior of programs compiled with GNU Fortran. ‘-fconvert=CONVERSION’ Specify the representation of data for unformatted files. Valid values for conversion on most systems are: ‘native’, the default; ‘swap’, swap between big- and little-endian; ‘big-endian’, use big-endian representation for unformatted files; ‘little-endian’, use little-endian representation for unformatted files. On POWER systems that suppport ‘-mabi=ieeelongdouble’, there are additional options, which can be combined with others with commas. Those are ‘-fconvert=r16_ieee’ Use IEEE 128-bit format for ‘REAL(KIND=16)’. ‘-fconvert=r16_ibm’ Use IBM long double format for ‘REAL(KIND=16)’. This option has an effect only when used in the main program. The ‘CONVERT’ specifier and the ‘GFORTRAN_CONVERT_UNIT’ environment variable override the default specified by ‘-fconvert’. ‘-frecord-marker=LENGTH’ Specify the length of record markers for unformatted files. Valid values for LENGTH are 4 and 8. Default is 4. _This is different from previous versions of ‘gfortran’_, which specified a default record marker length of 8 on most systems. If you want to read or write files compatible with earlier versions of ‘gfortran’, use ‘-frecord-marker=8’. ‘-fmax-subrecord-length=LENGTH’ Specify the maximum length for a subrecord. The maximum permitted value for length is 2147483639, which is also the default. Only really useful for use by the gfortran testsuite. ‘-fsign-zero’ When enabled, floating point numbers of value zero with the sign bit set are written as negative number in formatted output and treated as negative in the ‘SIGN’ intrinsic. ‘-fno-sign-zero’ does not print the negative sign of zero values (or values rounded to zero for I/O) and regards zero as positive number in the ‘SIGN’ intrinsic for compatibility with Fortran 77. The default is ‘-fsign-zero’.  File: gfortran.info, Node: Developer Options, Next: Code Gen Options, Prev: Runtime Options, Up: Invoking GNU Fortran 2.9 GNU Fortran Developer Options ================================= GNU Fortran has various special options that are used for debugging the GNU Fortran compiler. ‘-fdump-fortran-global’ Output a list of the global identifiers after translating into middle-end representation. Mostly useful for debugging the GNU Fortran compiler itself. The output generated by this option might change between releases. This option may also generate internal compiler errors for features that have only recently been added. ‘-fdump-fortran-optimized’ Output the parse tree after front-end optimization. Mostly useful for debugging the GNU Fortran compiler itself. The output generated by this option might change between releases. This option may also generate internal compiler errors for features that have only recently been added. ‘-fdump-fortran-original’ Output the internal parse tree after translating the source program into internal representation. This option is mostly useful for debugging the GNU Fortran compiler itself. The output generated by this option might change between releases. This option may also generate internal compiler errors for features that have only recently been added. ‘-fdump-parse-tree’ Output the internal parse tree after translating the source program into internal representation. Mostly useful for debugging the GNU Fortran compiler itself. The output generated by this option might change between releases. This option may also generate internal compiler errors for features that have only recently been added. This option is deprecated; use ‘-fdump-fortran-original’ instead. ‘-save-temps’ Store the usual "temporary" intermediate files permanently; name them as auxiliary output files, as specified described under GCC ‘-dumpbase’ and ‘-dumpdir’. gfortran -save-temps -c foo.F90 preprocesses input file ‘foo.F90’ to ‘foo.fii’, compiles to an intermediate ‘foo.s’, and then assembles to the (implied) output file ‘foo.o’, whereas: gfortran -save-temps -S foo.F saves the preprocessor output in ‘foo.fi’, and then compiles to the (implied) output file ‘foo.s’.  File: gfortran.info, Node: Code Gen Options, Next: Interoperability Options, Prev: Developer Options, Up: Invoking GNU Fortran 2.10 Options for code generation conventions ============================================ These machine-independent options control the interface conventions used in code generation. Most of them have both positive and negative forms; the negative form of ‘-ffoo’ would be ‘-fno-foo’. In the table below, only one of the forms is listed--the one that is not the default. You can figure out the other form by either removing ‘no-’ or adding it. ‘-fno-automatic’ Treat each program unit (except those marked as ‘RECURSIVE’) as if the ‘SAVE’ statement were specified for every local variable and array referenced in it. Does not affect common blocks. (Some Fortran compilers provide this option under the name ‘-static’ or ‘-save’.) The default, which is ‘-fautomatic’, uses the stack for local variables smaller than the value given by ‘-fmax-stack-var-size’. Use the option ‘-frecursive’ to use no static memory. Local variables or arrays having an explicit ‘SAVE’ attribute are silently ignored unless the ‘-pedantic’ option is added. ‘-ff2c’ Generate code designed to be compatible with code generated by ‘g77’ and ‘f2c’. The calling conventions used by ‘g77’ (originally implemented in ‘f2c’) require functions that return type default ‘REAL’ to actually return the C type ‘double’, and functions that return type ‘COMPLEX’ to return the values via an extra argument in the calling sequence that points to where to store the return value. Under the default GNU calling conventions, such functions simply return their results as they would in GNU C--default ‘REAL’ functions return the C type ‘float’, and ‘COMPLEX’ functions return the GNU C type ‘complex’. Additionally, this option implies the ‘-fsecond-underscore’ option, unless ‘-fno-second-underscore’ is explicitly requested. This does not affect the generation of code that interfaces with the ‘libgfortran’ library. _Caution:_ It is not a good idea to mix Fortran code compiled with ‘-ff2c’ with code compiled with the default ‘-fno-f2c’ calling conventions as, calling ‘COMPLEX’ or default ‘REAL’ functions between program parts that were compiled with different calling conventions will break at execution time. _Caution:_ This breaks code that passes intrinsic functions of type default ‘REAL’ or ‘COMPLEX’ as actual arguments, as the library implementations use the ‘-fno-f2c’ calling conventions. ‘-fno-underscoring’ Do not transform names of entities specified in the Fortran source file by appending underscores to them. With ‘-funderscoring’ in effect, GNU Fortran appends one underscore to external names. This is done to ensure compatibility with code produced by many UNIX Fortran compilers. Note this does not apply to names declared with C binding, or within a module. _Caution_: The default behavior of GNU Fortran is incompatible with ‘f2c’ and ‘g77’, please use the ‘-ff2c’ option if you want object files compiled with GNU Fortran to be compatible with object code created with these tools. Use of ‘-fno-underscoring’ is not recommended unless you are experimenting with issues such as integration of GNU Fortran into existing system environments (vis-à-vis existing libraries, tools, and so on). For example, with ‘-funderscoring’, and assuming that ‘j()’ and ‘max_count()’ are external functions while ‘my_var’ and ‘lvar’ are local variables, a Fortran statement like I = J() + MAX_COUNT (MY_VAR, LVAR) is implemented as something akin to the C code: i = j_() + max_count_(&my_var, &lvar); With ‘-fno-underscoring’, the same statement is implemented as: i = j() + max_count(&my_var, &lvar); Use of ‘-fno-underscoring’ allows direct specification of user-defined names while debugging and when interfacing GNU Fortran code with other languages. Note that just because the names match does _not_ mean that the interface implemented by GNU Fortran for an external name matches the interface implemented by some other language for that same name. That is, getting code produced by GNU Fortran to link to code produced by some other compiler using this or any other method can be only a small part of the overall solution--getting the code generated by both compilers to agree on issues other than naming can require significant effort, and, unlike naming disagreements, linkers normally cannot detect disagreements in these other areas. Also, note that with ‘-fno-underscoring’, the lack of appended underscores introduces the very real possibility that a user-defined external name conflicts with a name in a system library, which could make finding unresolved-reference bugs quite difficult in some cases--they might occur at program run time, and show up only as buggy behavior at run time. *Note Naming and argument-passing conventions::, for more information. Also note that declaring symbols as ‘bind(C)’ is a more robust way to interface with code written in other languages or compiled with different Fortran compilers than the command-line options documented in this section. ‘-fsecond-underscore’ By default, GNU Fortran appends an underscore to external names. If this option is used, GNU Fortran appends two underscores to names with underscores and one underscore to names with no underscores. For example, an external name such as ‘MAX_COUNT’ is implemented as a reference to the link-time external symbol ‘max_count__’, instead of ‘max_count_’. This is required for compatibility with ‘g77’ and ‘f2c’, and is implied by use of the ‘-ff2c’ option. This option has no effect if ‘-fno-underscoring’ is in effect. It is implied by the ‘-ff2c’ option. ‘-fcoarray=’ ‘none’ Disable coarray support; using coarray declarations and image-control statements produces a compile-time error. (Default) ‘single’ Single-image mode, i.e. ‘num_images()’ is always one. ‘lib’ Library-based coarray parallelization; a suitable GNU Fortran coarray library such as needs to be linked. Alternatively, GCC's ‘libcaf_single’ library can be linked, albeit it only supports a single image. ‘-fcheck=’ Enable the generation of run-time checks; the argument shall be a comma-delimited list of the following keywords. Prefixing a check with ‘no-’ disables it if it was activated by a previous specification. ‘all’ Enable all run-time test of ‘-fcheck’. ‘array-temps’ Warns at run time when for passing an actual argument a temporary array had to be generated. The information generated by this warning is sometimes useful in optimization, in order to avoid such temporaries. Note: The warning is only printed once per location. ‘bits’ Enable generation of run-time checks for invalid arguments to the bit manipulation intrinsics. ‘bounds’ Enable generation of run-time checks for array subscripts and against the declared minimum and maximum values. It also checks array indices for assumed and deferred shape arrays against the actual allocated bounds and ensures that all string lengths are equal for character array constructors without an explicit typespec. Some checks require that ‘-fcheck=bounds’ is set for the compilation of the main program. Note: In the future this may also include other forms of checking, e.g., checking substring references. ‘do’ Enable generation of run-time checks for invalid modification of loop iteration variables. ‘mem’ Enable generation of run-time checks for memory allocation. Note: This option does not affect explicit allocations using the ‘ALLOCATE’ statement, which are always checked. ‘pointer’ Enable generation of run-time checks for pointers and allocatables. ‘recursion’ Enable generation of run-time checks for recursively called subroutines and functions that are not marked as recursive. See also ‘-frecursive’. Note: This check does not work for OpenMP programs and is disabled if used together with ‘-frecursive’ and ‘-fopenmp’. Example: Assuming you have a file ‘foo.f90’, the command gfortran -fcheck=all,no-array-temps foo.f90 compiles the file with all checks enabled as specified above except warnings for generated array temporaries. ‘-fbounds-check’ Deprecated alias for ‘-fcheck=bounds’. ‘-ftail-call-workaround’ ‘-ftail-call-workaround=N’ Some C interfaces to Fortran codes violate the gfortran ABI by omitting the hidden character length arguments as described in *Note Argument passing conventions::. This can lead to crashes because pushing arguments for tail calls can overflow the stack. To provide a workaround for existing binary packages, this option disables tail call optimization for gfortran procedures with character arguments. With ‘-ftail-call-workaround=2’ tail call optimization is disabled in all gfortran procedures with character arguments, with ‘-ftail-call-workaround=1’ or equivalent ‘-ftail-call-workaround’ only in gfortran procedures with character arguments that call implicitly prototyped procedures. Using this option can lead to problems including crashes due to insufficient stack space. It is _very strongly_ recommended to fix the code in question. The ‘-fc-prototypes-external’ option can be used to generate prototypes that conform to gfortran's ABI, for inclusion in the source code. Support for this option will likely be withdrawn in a future release of gfortran. The negative form, ‘-fno-tail-call-workaround’ or equivalent ‘-ftail-call-workaround=0’, can be used to disable this option. Default is currently ‘-ftail-call-workaround’, this will change in future releases. ‘-fcheck-array-temporaries’ Deprecated alias for ‘-fcheck=array-temps’. ‘-fmax-array-constructor=N’ This option can be used to increase the upper limit permitted in array constructors. The code below requires this option to expand the array at compile time. program test implicit none integer j integer, parameter :: n = 100000 integer, parameter :: i(n) = (/ (2*j, j = 1, n) /) print '(10(I0,1X))', i end program test _Caution: This option can lead to long compile times and excessively large object files._ The default value for N is 65535. ‘-fmax-stack-var-size=N’ This option specifies the size in bytes of the largest array that is put on the stack; if the size is exceeded static memory is used (except in procedures marked as ‘RECURSIVE’). Use the option ‘-frecursive’ to allow for recursive procedures that do not have a ‘RECURSIVE’ attribute or for parallel programs. Use ‘-fno-automatic’ to never use the stack. This option currently only affects local arrays declared with constant bounds, and may not apply to all character variables. Future versions of GNU Fortran may improve this behavior. The default value for N is 65536. ‘-fstack-arrays’ Adding this option makes the Fortran compiler put all arrays of unknown size and array temporaries onto stack memory. If your program uses very large local arrays it is possible that you have to extend your runtime limits for stack memory on some operating systems. This flag is enabled by default at optimization level ‘-Ofast’ unless ‘-fmax-stack-var-size’ is specified. ‘-fpack-derived’ This option tells GNU Fortran to pack derived type members as closely as possible. Code compiled with this option is likely to be incompatible with code compiled without this option, and may execute slower. ‘-frepack-arrays’ In some circumstances GNU Fortran may pass assumed shape array sections via a descriptor describing a noncontiguous area of memory. This option adds code to the function prologue to repack the data into a contiguous block at runtime. This should result in faster accesses to the array. However it can introduce significant overhead to the function call, especially when the passed data is noncontiguous. ‘-fshort-enums’ This option is provided for interoperability with C code that was compiled with the ‘-fshort-enums’ option. It makes GNU Fortran choose the smallest ‘INTEGER’ kind a given enumerator set fits in, and give all its enumerators this kind. ‘-finline-arg-packing’ When passing an assumed-shape argument of a procedure as actual argument to an assumed-size or explicit size or as argument to a procedure that does not have an explicit interface, the argument may have to be packed; that is, put into contiguous memory. An example is the call to ‘foo’ in subroutine foo(a) real, dimension(*) :: a end subroutine foo subroutine bar(b) real, dimension(:) :: b call foo(b) end subroutine bar When ‘-finline-arg-packing’ is in effect, this packing is performed by inline code. This allows for more optimization while increasing code size. ‘-finline-arg-packing’ is implied by any of the ‘-O’ options except when optimizing for size via ‘-Os’. If the code contains a very large number of argument that have to be packed, code size and also compilation time may become excessive. If that is the case, it may be better to disable this option. Instances of packing can be found by using ‘-Warray-temporaries’. ‘-fexternal-blas’ This option makes ‘gfortran’ generate calls to BLAS functions for some matrix operations like ‘MATMUL’, instead of using our own algorithms, if the size of the matrices involved is larger than a given limit (see ‘-fblas-matmul-limit’). This may be profitable if an optimized vendor BLAS library is available. The BLAS library has to be specified at link time. ‘-fblas-matmul-limit=N’ Only significant when ‘-fexternal-blas’ is in effect. Matrix multiplication of matrices with size larger than (or equal to) N is performed by calls to BLAS functions, while others are handled by ‘gfortran’ internal algorithms. If the matrices involved are not square, the size comparison is performed using the geometric mean of the dimensions of the argument and result matrices. The default value for N is 30. ‘-finline-intrinsics’ ‘-finline-intrinsics=INTR1,INTR2,...’ Prefer generating inline code over calls to libgfortran functions to implement intrinsics. Usage of intrinsics can be implemented either by generating a call to the libgfortran library function or by directly generating inline code. For most intrinsics, only a single variant is available, and there is no choice of implementation. However, some intrinsics can use a library function or inline code, where inline code typically offers opportunities for additional optimization over a library function. With ‘-finline-intrinsics=...’ or ‘-fno-inline-intrinsics=...’, the choice applies only to the intrinsics present in the comma-separated list provided as argument. For each intrinsic, if no choice of implementation was made through either of the flag variants, a default behavior is chosen depending on optimization: library calls are generated when not optimizing or when optimizing for size; otherwise inline code is preferred. The set of intrinsics allowed as argument to ‘-finline-intrinsics=’ is currently limited to ‘MAXLOC’ and ‘MINLOC’. The effect of the flag is moreover limited to calls of those intrinsics without ‘DIM’ argument and with ‘ARRAY’ of a non-‘CHARACTER’ type. The case of rank-1 argument and ‘DIM’ argument present, i.e. ‘MAXLOC(A(:),DIM=1)’ or ‘MINLOC(A(:),DIM=1)’ is inlined unconditionally for numeric rank-1 array argument ‘A’. ‘-finline-matmul-limit=N’ When front-end optimization is active, some calls to the ‘MATMUL’ intrinsic function are inlined. This may result in code size increase if the size of the matrix cannot be determined at compile time, as code for both cases is generated. Setting ‘-finline-matmul-limit=0’ disables inlining in all cases. Setting this option with a value of N produces inline code for matrices with size up to N. If the matrices involved are not square, the size comparison is performed using the geometric mean of the dimensions of the argument and result matrices. The default value for N is 30. The ‘-fblas-matmul-limit’ can be used to change this value. ‘-frecursive’ Allow indirect recursion by forcing all local arrays to be allocated on the stack. This flag cannot be used together with ‘-fmax-stack-var-size=’ or ‘-fno-automatic’. ‘-finit-local-zero’ ‘-finit-derived’ ‘-finit-integer=N’ ‘-finit-real=’ ‘-finit-logical=’ ‘-finit-character=N’ The ‘-finit-local-zero’ option instructs the compiler to initialize local ‘INTEGER’, ‘REAL’, and ‘COMPLEX’ variables to zero, ‘LOGICAL’ variables to false, and ‘CHARACTER’ variables to a string of null bytes. Finer-grained initialization options are provided by the ‘-finit-integer=N’, ‘-finit-real=’ (which also initializes the real and imaginary parts of local ‘COMPLEX’ variables), ‘-finit-logical=’, and ‘-finit-character=N’ (where N is an ASCII character value) options. With ‘-finit-derived’, components of derived type variables are initialized according to these flags. Components whose type is not covered by an explicit ‘-finit-*’ flag are treated as described above with ‘-finit-local-zero’. These options do not initialize • objects with the ‘POINTER’ attribute • allocatable arrays • variables that appear in an ‘EQUIVALENCE’ statement. (These limitations may be removed in future releases). Note that the ‘-finit-real=nan’ option initializes ‘REAL’ and ‘COMPLEX’ variables with a quiet NaN. For a signalling NaN use ‘-finit-real=snan’; note, however, that compile-time optimizations may convert them into quiet NaN and that trapping needs to be enabled (e.g. via ‘-ffpe-trap’). The ‘-finit-integer’ option parses the value into an integer of type ‘INTEGER(kind=C_LONG)’ on the host. Said value is then assigned to the integer variables in the Fortran code, which might result in wraparound if the value is too large for the kind. Finally, note that enabling any of the ‘-finit-*’ options silences warnings that would have been emitted by ‘-Wuninitialized’ for the affected local variables. ‘-falign-commons’ By default, ‘gfortran’ enforces proper alignment of all variables in a ‘COMMON’ block by padding them as needed. On certain platforms this is mandatory, on others it increases performance. If a ‘COMMON’ block is not declared with consistent data types everywhere, this padding can cause trouble, and ‘-fno-align-commons’ can be used to disable automatic alignment. The same form of this option should be used for all files that share a ‘COMMON’ block. To avoid potential alignment issues in ‘COMMON’ blocks, it is recommended to order objects from largest to smallest. ‘-fno-protect-parens’ By default the parentheses in expression are honored for all optimization levels such that the compiler does not do any reassociation. Using ‘-fno-protect-parens’ allows the compiler to reorder ‘REAL’ and ‘COMPLEX’ expressions to produce faster code. Note that for the reassociation optimization ‘-fno-signed-zeros’ and ‘-fno-trapping-math’ need to be in effect. The parentheses protection is enabled by default, unless ‘-Ofast’ is given. ‘-frealloc-lhs’ An allocatable left-hand side of an intrinsic assignment is automatically (re)allocated if it is either unallocated or has a different shape. The option is enabled by default except when ‘-std=f95’ is given. See also ‘-Wrealloc-lhs’. ‘-faggressive-function-elimination’ Functions with identical argument lists are eliminated within statements, regardless of whether these functions are marked ‘PURE’ or not. For example, in a = f(b,c) + f(b,c) there is only a single call to ‘f’. This option only works if ‘-ffrontend-optimize’ is in effect. ‘-ffrontend-optimize’ This option performs front-end optimization, based on manipulating parts of the Fortran parse tree. Enabled by default by any ‘-O’ option except ‘-O0’ and ‘-Og’. Optimizations enabled by this option include: • inlining calls to ‘MATMUL’, • elimination of identical function calls within expressions, • removing unnecessary calls to ‘TRIM’ in comparisons and assignments, • replacing ‘TRIM(a)’ with ‘a(1:LEN_TRIM(a))’ and • short-circuiting of logical operators (‘.AND.’ and ‘.OR.’). It can be deselected by specifying ‘-fno-frontend-optimize’. ‘-ffrontend-loop-interchange’ Attempt to interchange loops in the Fortran front end where profitable. Enabled by default by any ‘-O’ option. At the moment, this option only affects ‘FORALL’ and ‘DO CONCURRENT’ statements with several forall triplets. *Note Options for Code Generation Conventions: (gcc)Code Gen Options, for information on more options offered by the back end shared by ‘gfortran’, ‘gcc’, and other GNU compilers.  File: gfortran.info, Node: Interoperability Options, Next: Environment Variables, Prev: Code Gen Options, Up: Invoking GNU Fortran 2.11 Options for interoperability with other languages ====================================================== ‘-fc-prototypes’ This option generates C prototypes from ‘BIND(C)’ variable declarations, types and procedure interfaces and writes them to standard output. ‘ENUM’ is not yet supported. The generated prototypes may need inclusion of an appropriate header, such as ‘’ or ‘’. For types that are not specified using the appropriate kind from the ‘iso_c_binding’ module, a warning is added as a comment to the code. For function pointers, a pointer to a function returning ‘int’ without an explicit argument list is generated. Example of use: $ gfortran -fc-prototypes -fsyntax-only foo.f90 > foo.h where the C code intended for interoperating with the Fortran code then uses ‘#include "foo.h"’. ‘-fc-prototypes-external’ This option generates C prototypes from external functions and subroutines and writes them to standard output. This may be useful for making sure that C bindings to Fortran code are correct. This option does not generate prototypes for ‘BIND(C)’ procedures; use ‘-fc-prototypes’ for that. The generated prototypes may need inclusion of an appropriate header, such as ‘’ or ‘’. This is primarily meant for legacy code to ensure that existing C bindings match what ‘gfortran’ emits. The generated C prototypes should be correct for the current version of the compiler, but may not match what other compilers or earlier versions of ‘gfortran’ need. For new development, use of the ‘BIND(C)’ features is recommended. Example of use: $ gfortran -fc-prototypes-external -fsyntax-only foo.f > foo.h where the C code intended for interoperating with the Fortran code then uses ‘#include "foo.h"’.  File: gfortran.info, Node: Environment Variables, Prev: Interoperability Options, Up: Invoking GNU Fortran 2.12 Environment variables affecting ‘gfortran’ =============================================== The ‘gfortran’ compiler currently does not make use of any environment variables to control its operation above and beyond those that affect the operation of ‘gcc’. *Note Environment Variables Affecting GCC: (gcc)Environment Variables, for information on environment variables. *Note Runtime::, for environment variables that affect the run-time behavior of programs compiled with GNU Fortran.  File: gfortran.info, Node: Runtime, Next: Compiler Characteristics, Prev: Invoking GNU Fortran, Up: Top 3 Runtime: Influencing runtime behavior with environment variables ****************************************************************** The behavior of the ‘gfortran’ can be influenced by environment variables. Malformed environment variables are silently ignored. * Menu: * TMPDIR:: Directory for scratch files * GFORTRAN_STDIN_UNIT:: Unit number for standard input * GFORTRAN_STDOUT_UNIT:: Unit number for standard output * GFORTRAN_STDERR_UNIT:: Unit number for standard error * GFORTRAN_UNBUFFERED_ALL:: Do not buffer I/O for all units * GFORTRAN_UNBUFFERED_PRECONNECTED:: Do not buffer I/O for preconnected units. * GFORTRAN_SHOW_LOCUS:: Show location for runtime errors * GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted * GFORTRAN_LIST_SEPARATOR:: Separator for list output * GFORTRAN_CONVERT_UNIT:: Set conversion for unformatted I/O * GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors * GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files * GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files  File: gfortran.info, Node: TMPDIR, Next: GFORTRAN_STDIN_UNIT, Up: Runtime 3.1 ‘TMPDIR’--Directory for scratch files ========================================= When opening a file with ‘STATUS='SCRATCH'’, GNU Fortran tries to create the file in one of the potential directories by testing each directory in the order below. 1. The environment variable ‘TMPDIR’, if it exists. 2. On the MinGW target, the directory returned by the ‘GetTempPath’ function. Alternatively, on the Cygwin target, the ‘TMP’ and ‘TEMP’ environment variables, if they exist, in that order. 3. The ‘P_tmpdir’ macro if it is defined, otherwise the directory ‘/tmp’.  File: gfortran.info, Node: GFORTRAN_STDIN_UNIT, Next: GFORTRAN_STDOUT_UNIT, Prev: TMPDIR, Up: Runtime 3.2 ‘GFORTRAN_STDIN_UNIT’--Unit number for standard input ========================================================= This environment variable can be used to select the unit number preconnected to standard input. This must be a positive integer. The default value is 5.  File: gfortran.info, Node: GFORTRAN_STDOUT_UNIT, Next: GFORTRAN_STDERR_UNIT, Prev: GFORTRAN_STDIN_UNIT, Up: Runtime 3.3 ‘GFORTRAN_STDOUT_UNIT’--Unit number for standard output =========================================================== This environment variable can be used to select the unit number preconnected to standard output. This must be a positive integer. The default value is 6.  File: gfortran.info, Node: GFORTRAN_STDERR_UNIT, Next: GFORTRAN_UNBUFFERED_ALL, Prev: GFORTRAN_STDOUT_UNIT, Up: Runtime 3.4 ‘GFORTRAN_STDERR_UNIT’--Unit number for standard error ========================================================== This environment variable can be used to select the unit number preconnected to standard error. This must be a positive integer. The default value is 0.  File: gfortran.info, Node: GFORTRAN_UNBUFFERED_ALL, Next: GFORTRAN_UNBUFFERED_PRECONNECTED, Prev: GFORTRAN_STDERR_UNIT, Up: Runtime 3.5 ‘GFORTRAN_UNBUFFERED_ALL’--Do not buffer I/O on all units ============================================================= This environment variable controls whether all I/O is unbuffered. If the first letter is ‘y’, ‘Y’ or ‘1’, all I/O is unbuffered. This slows down small sequential reads and writes. If the first letter is ‘n’, ‘N’ or ‘0’, I/O is buffered. This is the default.  File: gfortran.info, Node: GFORTRAN_UNBUFFERED_PRECONNECTED, Next: GFORTRAN_SHOW_LOCUS, Prev: GFORTRAN_UNBUFFERED_ALL, Up: Runtime 3.6 ‘GFORTRAN_UNBUFFERED_PRECONNECTED’--Do not buffer I/O on preconnected units =============================================================================== The environment variable named ‘GFORTRAN_UNBUFFERED_PRECONNECTED’ controls whether I/O on a preconnected unit (i.e. STDOUT or STDERR) is unbuffered. If the first letter is ‘y’, ‘Y’ or ‘1’, I/O is unbuffered. This slows down small sequential reads and writes. If the first letter is ‘n’, ‘N’ or ‘0’, I/O is buffered. This is the default.  File: gfortran.info, Node: GFORTRAN_SHOW_LOCUS, Next: GFORTRAN_OPTIONAL_PLUS, Prev: GFORTRAN_UNBUFFERED_PRECONNECTED, Up: Runtime 3.7 ‘GFORTRAN_SHOW_LOCUS’--Show location for runtime errors =========================================================== If the first letter is ‘y’, ‘Y’ or ‘1’, filename and line numbers for runtime errors are printed. If the first letter is ‘n’, ‘N’ or ‘0’, do not print filename and line numbers for runtime errors. The default is to print the location.  File: gfortran.info, Node: GFORTRAN_OPTIONAL_PLUS, Next: GFORTRAN_LIST_SEPARATOR, Prev: GFORTRAN_SHOW_LOCUS, Up: Runtime 3.8 ‘GFORTRAN_OPTIONAL_PLUS’--Print leading + where permitted ============================================================= If the first letter is ‘y’, ‘Y’ or ‘1’, a plus sign is printed where permitted by the Fortran standard. If the first letter is ‘n’, ‘N’ or ‘0’, a plus sign is not printed in most cases. Default is not to print plus signs.  File: gfortran.info, Node: GFORTRAN_LIST_SEPARATOR, Next: GFORTRAN_CONVERT_UNIT, Prev: GFORTRAN_OPTIONAL_PLUS, Up: Runtime 3.9 ‘GFORTRAN_LIST_SEPARATOR’--Separator for list output ======================================================== This environment variable specifies the separator when writing list-directed output. It may contain any number of spaces and at most one comma. If you specify this on the command line, be sure to quote spaces, as in $ GFORTRAN_LIST_SEPARATOR=' , ' ./a.out when ‘a.out’ is the compiled Fortran program that you want to run. Default is a single space.  File: gfortran.info, Node: GFORTRAN_CONVERT_UNIT, Next: GFORTRAN_ERROR_BACKTRACE, Prev: GFORTRAN_LIST_SEPARATOR, Up: Runtime 3.10 ‘GFORTRAN_CONVERT_UNIT’--Set conversion for unformatted I/O ================================================================ By setting the ‘GFORTRAN_CONVERT_UNIT’ variable, it is possible to change the representation of data for unformatted files. The syntax for the ‘GFORTRAN_CONVERT_UNIT’ variable for most systems is: GFORTRAN_CONVERT_UNIT: mode | mode ';' exception | exception ; mode: 'native' | 'swap' | 'big_endian' | 'little_endian' ; exception: mode ':' unit_list | unit_list ; unit_list: unit_spec | unit_list unit_spec ; unit_spec: INTEGER | INTEGER '-' INTEGER ; The variable consists of an optional default mode, followed by a list of optional exceptions, which are separated by semicolons from the preceding default and each other. Each exception consists of a format and a comma-separated list of units. Valid values for the modes are the same as for the ‘CONVERT’ specifier: ‘NATIVE’ Use the native format. This is the default. ‘SWAP’ Swap between little- and big-endian. ‘LITTLE_ENDIAN’ Use the little-endian format for unformatted files. ‘BIG_ENDIAN’ Use the big-endian format for unformatted files. For POWER systems that support ‘-mabi=ieeelongdouble’, there are additional options, which can be combined with the others with commas. Those are ‘R16_IEEE’ Use IEEE 128-bit format for ‘REAL(KIND=16)’. ‘R16_IBM’ Use IBM ‘long double’ format for ‘REAL(KIND=16)’. A missing mode for an exception is taken to mean ‘BIG_ENDIAN’. Examples of values for ‘GFORTRAN_CONVERT_UNIT’ are: ‘'big_endian'’ Do all unformatted I/O in big_endian mode. ‘'little_endian;native:10-20,25'’ Do all unformatted I/O in little_endian mode, except for units 10 to 20 and 25, which are in native format. ‘'10-20'’ Units 10 to 20 are big-endian, the rest is native. ‘'big_endian,r16_ibm'’ Do all unformatted I/O in big-endian mode and use IBM long double for output of ‘REAL(KIND=16)’ values. Setting the environment variables should be done on the command line or via the ‘export’ command for ‘sh’-compatible shells and via ‘setenv’ for ‘csh’-compatible shells. Example for ‘sh’: $ gfortran foo.f90 $ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out Example code for ‘csh’: % gfortran foo.f90 % setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20' % ./a.out Using anything but the native representation for unformatted data carries a significant speed overhead. If speed in this area matters to you, it is best if you use this only for data that needs to be portable. *Note CONVERT specifier::, for an alternative way to specify the data representation for unformatted files. *Note Runtime Options::, for setting a default data representation for the whole program. The ‘CONVERT’ specifier overrides the ‘-fconvert’ compile options. Note that the values specified via the ‘GFORTRAN_CONVERT_UNIT’ environment variable override the ‘CONVERT’ specifier in the ‘OPEN’ statement. This is to give control over data formats to users who do not have the source code of their program available.  File: gfortran.info, Node: GFORTRAN_ERROR_BACKTRACE, Next: GFORTRAN_FORMATTED_BUFFER_SIZE, Prev: GFORTRAN_CONVERT_UNIT, Up: Runtime 3.11 ‘GFORTRAN_ERROR_BACKTRACE’--Show backtrace on run-time errors ================================================================== If the ‘GFORTRAN_ERROR_BACKTRACE’ variable is set to ‘y’, ‘Y’ or ‘1’ (only the first letter is relevant) then a backtrace is printed when a serious run-time error occurs. To disable the backtracing, set the variable to ‘n’, ‘N’, ‘0’. Default is to print a backtrace unless the ‘-fno-backtrace’ compile option was used.  File: gfortran.info, Node: GFORTRAN_FORMATTED_BUFFER_SIZE, Next: GFORTRAN_UNFORMATTED_BUFFER_SIZE, Prev: GFORTRAN_ERROR_BACKTRACE, Up: Runtime 3.12 ‘GFORTRAN_FORMATTED_BUFFER_SIZE’--Set buffer size for formatted I/O ======================================================================== The ‘GFORTRAN_FORMATTED_BUFFER_SIZE’ environment variable specifies buffer size in bytes to be used for formatted output. The default value is 8192.  File: gfortran.info, Node: GFORTRAN_UNFORMATTED_BUFFER_SIZE, Prev: GFORTRAN_FORMATTED_BUFFER_SIZE, Up: Runtime 3.13 ‘GFORTRAN_UNFORMATTED_BUFFER_SIZE’--Set buffer size for unformatted I/O ============================================================================ The ‘GFORTRAN_UNFORMATTED_BUFFER_SIZE’ environment variable specifies buffer size in bytes to be used for unformatted output. The default value is 131072.  File: gfortran.info, Node: Compiler Characteristics, Next: Extensions, Prev: Runtime, Up: Top 4 Compiler Characteristics ************************** This chapter describes certain characteristics of the GNU Fortran compiler that are not specified by the Fortran standard, but which might in some way or another become visible to the programmer. * Menu: * KIND Type Parameters:: * Internal representation of LOGICAL variables:: * Evaluation of logical expressions:: * MAX and MIN intrinsics with REAL NaN arguments:: * Thread-safety of the runtime library:: * Data consistency and durability:: * Files opened without an explicit ACTION= specifier:: * File operations on symbolic links:: * File format of unformatted sequential files:: * Asynchronous I/O:: * Behavior on integer overflow::  File: gfortran.info, Node: KIND Type Parameters, Next: Internal representation of LOGICAL variables, Up: Compiler Characteristics 4.1 ‘KIND’ Type Parameters ========================== The ‘KIND’ type parameters supported by GNU Fortran for the primitive data types are: ‘INTEGER’ 1, 2, 4, 8*, 16*, default: 4** ‘LOGICAL’ 1, 2, 4, 8*, 16*, default: 4** ‘REAL’ 4, 8, 10*, 16*, default: 4*** ‘COMPLEX’ 4, 8, 10*, 16*, default: 4*** ‘DOUBLE PRECISION’ 4, 8, 10*, 16*, default: 8*** ‘CHARACTER’ 1, 4, default: 1 * not available on all systems ** unless ‘-fdefault-integer-8’ is used *** unless ‘-fdefault-real-8’ is used (see *note Fortran Dialect Options::) The ‘KIND’ value matches the storage size in bytes, except for ‘COMPLEX’ where the storage size is twice as much (or both real and imaginary part are a real value of the given size). It is recommended to use the *note SELECTED_CHAR_KIND::, *note SELECTED_INT_KIND::, *note SELECTED_LOGICAL_KIND:: and *note SELECTED_REAL_KIND:: intrinsics or the ‘INT8’, ‘INT16’, ‘INT32’, ‘INT64’, ‘REAL32’, ‘REAL64’, and ‘REAL128’ parameters of the ‘ISO_FORTRAN_ENV’ module instead of the concrete values. The available kind parameters can be found in the constant arrays ‘CHARACTER_KINDS’, ‘INTEGER_KINDS’, ‘LOGICAL_KINDS’ and ‘REAL_KINDS’ in the *note ISO_FORTRAN_ENV:: module. For C interoperability, the kind parameters of the *note ISO_C_BINDING:: module should be used.  File: gfortran.info, Node: Internal representation of LOGICAL variables, Next: Evaluation of logical expressions, Prev: KIND Type Parameters, Up: Compiler Characteristics 4.2 Internal representation of ‘LOGICAL’ variables ================================================== The Fortran standard does not specify how variables of ‘LOGICAL’ type are represented, beyond requiring that ‘LOGICAL’ variables of default kind have the same storage size as default ‘INTEGER’ and ‘REAL’ variables. The GNU Fortran internal representation is as follows. A ‘LOGICAL(KIND=N)’ variable is represented as an ‘INTEGER(KIND=N)’ variable, however, with only two permissible values: ‘1’ for ‘.TRUE.’ and ‘0’ for ‘.FALSE.’. Any other integer value results in undefined behavior. See also *note Argument passing conventions:: and *note Interoperability with C::.  File: gfortran.info, Node: Evaluation of logical expressions, Next: MAX and MIN intrinsics with REAL NaN arguments, Prev: Internal representation of LOGICAL variables, Up: Compiler Characteristics 4.3 Evaluation of logical expressions ===================================== The Fortran standard does not require the compiler to evaluate all parts of an expression, if they do not contribute to the final result. For logical expressions with ‘.AND.’ or ‘.OR.’ operators, in particular, GNU Fortran optimizes out function calls (even to impure functions) if the result of the expression can be established without them. However, since not all compilers do that, and such an optimization can potentially modify the program flow and subsequent results, GNU Fortran throws warnings for such situations with the ‘-Wfunction-elimination’ flag.  File: gfortran.info, Node: MAX and MIN intrinsics with REAL NaN arguments, Next: Thread-safety of the runtime library, Prev: Evaluation of logical expressions, Up: Compiler Characteristics 4.4 ‘MAX’ and ‘MIN’ intrinsics with ‘REAL’ NaN arguments ======================================================== The Fortran standard does not specify what the result of the ‘MAX’ and ‘MIN’ intrinsics are if one of the arguments is a ‘NaN’. Accordingly, the GNU Fortran compiler does not specify that either, as this allows for faster and more compact code to be generated. If the programmer wishes to take some specific action in case one of the arguments is a ‘NaN’, it is necessary to explicitly test the arguments before calling ‘MAX’ or ‘MIN’, e.g. with the ‘IEEE_IS_NAN’ function from the intrinsic module ‘IEEE_ARITHMETIC’.  File: gfortran.info, Node: Thread-safety of the runtime library, Next: Data consistency and durability, Prev: MAX and MIN intrinsics with REAL NaN arguments, Up: Compiler Characteristics 4.5 Thread-safety of the runtime library ======================================== GNU Fortran can be used in programs with multiple threads, e.g. by using OpenMP, by calling OS thread handling functions via the ‘ISO_C_BINDING’ facility, or by GNU Fortran compiled library code being called from a multi-threaded program. The GNU Fortran runtime library, (‘libgfortran’), supports being called concurrently from multiple threads with the following exceptions. During library initialization, the C ‘getenv’ function is used, which need not be thread-safe. Similarly, the ‘getenv’ function is used to implement the ‘GET_ENVIRONMENT_VARIABLE’ and ‘GETENV’ intrinsics. It is the responsibility of the user to ensure that the environment is not being updated concurrently when any of these actions are taking place. The ‘EXECUTE_COMMAND_LINE’ and ‘SYSTEM’ intrinsics are implemented with the ‘system’ function, which need not be thread-safe. It is the responsibility of the user to ensure that ‘system’ is not called concurrently. For platforms not supporting thread-safe POSIX functions, further functionality might not be thread-safe. For details, please consult the documentation for your operating system. The GNU Fortran runtime library uses various C library functions that depend on the locale, such as ‘strtod’ and ‘snprintf’. In order to work correctly in locale-aware programs that set the locale using ‘setlocale’, the locale is reset to the default "C" locale while executing a formatted ‘READ’ or ‘WRITE’ statement. On targets supporting the POSIX 2008 per-thread locale functions (e.g. ‘newlocale’, ‘uselocale’, ‘freelocale’), these are used and thus the global locale set using ‘setlocale’ or the per-thread locales in other threads are not affected. However, on targets lacking this functionality, the global LC_NUMERIC locale is set to "C" during the formatted I/O. Thus, on such targets it's not safe to call ‘setlocale’ concurrently from another thread while a Fortran formatted I/O operation is in progress. Also, other threads doing something dependent on the LC_NUMERIC locale might not work correctly if a formatted I/O operation is in progress in another thread.  File: gfortran.info, Node: Data consistency and durability, Next: Files opened without an explicit ACTION= specifier, Prev: Thread-safety of the runtime library, Up: Compiler Characteristics 4.6 Data consistency and durability =================================== This section contains a brief overview of data and metadata consistency and durability issues when doing I/O. With respect to durability, GNU Fortran makes no effort to ensure that data is committed to stable storage. If this is required, the GNU Fortran programmer can use the intrinsic ‘FNUM’ to retrieve the low level file descriptor corresponding to an open Fortran unit. Then, using e.g. the ‘ISO_C_BINDING’ feature, one can call the underlying system call to flush dirty data to stable storage, such as ‘fsync’ on POSIX, ‘_commit’ on MinGW, or ‘fcntl(fd, F_FULLSYNC, 0)’ on macOS. The following example shows how to call fsync: ! Declare the interface for POSIX fsync function interface function fsync (fd) bind(c,name="fsync") use iso_c_binding, only: c_int integer(c_int), value :: fd integer(c_int) :: fsync end function fsync end interface ! Variable declaration integer :: ret ! Opening unit 10 open (10,file="foo") ! ... ! Perform I/O on unit 10 ! ... ! Flush and sync flush(10) ret = fsync(fnum(10)) ! Handle possible error if (ret /= 0) stop "Error calling FSYNC" With respect to consistency, for regular files GNU Fortran uses buffered I/O in order to improve performance. This buffer is flushed automatically when full and in some other situations, e.g. when closing a unit. It can also be explicitly flushed with the ‘FLUSH’ statement. Also, the buffering can be turned off with the ‘GFORTRAN_UNBUFFERED_ALL’ and ‘GFORTRAN_UNBUFFERED_PRECONNECTED’ environment variables. Special files, such as terminals and pipes, are always unbuffered. Sometimes, however, further things may need to be done in order to allow other processes to see data that GNU Fortran has written, as follows. The Windows platform supports a relaxed metadata consistency model, where file metadata is written to the directory lazily. This means that, for instance, the ‘dir’ command can show a stale size for a file. One can force a directory metadata update by closing the unit, or by calling ‘_commit’ on the file descriptor. Note, though, that ‘_commit’ forces all dirty data to stable storage, which is often a very slow operation. The Network File System (NFS) implements a relaxed consistency model called open-to-close consistency. Closing a file forces dirty data and metadata to be flushed to the server, and opening a file forces the client to contact the server in order to revalidate cached data. ‘fsync’ also forces a flush of dirty data and metadata to the server. Similar to ‘open’ and ‘close’, acquiring and releasing ‘fcntl’ file locks, if the server supports them, also forces cache validation and flushing dirty data and metadata.  File: gfortran.info, Node: Files opened without an explicit ACTION= specifier, Next: File operations on symbolic links, Prev: Data consistency and durability, Up: Compiler Characteristics 4.7 Files opened without an explicit ‘ACTION=’ specifier ======================================================== The Fortran standard says that if an ‘OPEN’ statement is executed without an explicit ‘ACTION=’ specifier, the default value is processor dependent. GNU Fortran behaves as follows: 1. Attempt to open the file with ‘ACTION='READWRITE'’ 2. If that fails, try to open with ‘ACTION='READ'’ 3. If that fails, try to open with ‘ACTION='WRITE'’ 4. If that fails, generate an error  File: gfortran.info, Node: File operations on symbolic links, Next: File format of unformatted sequential files, Prev: Files opened without an explicit ACTION= specifier, Up: Compiler Characteristics 4.8 File operations on symbolic links ===================================== This section documents the behavior of GNU Fortran for file operations on symbolic links, on systems that support them. • Results of ‘INQUIRE’ statements of the "inquire by file" form relate to the target of the symbolic link. For example, ‘INQUIRE(FILE="foo",EXIST=ex)’ sets EX to .TRUE. if FOO is a symbolic link pointing to an existing file, and .FALSE. if FOO points to an non-existing file ("dangling" symbolic link). • Using the ‘OPEN’ statement with a ‘STATUS="NEW"’ specifier on a symbolic link results in an error condition, whether the symbolic link points to an existing target or is dangling. • If a symbolic link was connected, using the ‘CLOSE’ statement with a ‘STATUS="DELETE"’ specifier causes the symbolic link itself to be deleted, not its target.  File: gfortran.info, Node: File format of unformatted sequential files, Next: Asynchronous I/O, Prev: File operations on symbolic links, Up: Compiler Characteristics 4.9 File format of unformatted sequential files =============================================== Unformatted sequential files are stored as logical records using record markers. Each logical record consists of one of more subrecords. Each subrecord consists of a leading record marker, the data written by the user program, and a trailing record marker. The record markers are four-byte integers by default, and eight-byte integers if the ‘-fmax-subrecord-length=8’ option (which exists for backwards compatibility only) is in effect. The representation of the record markers is that of unformatted files given with the ‘-fconvert’ option, the *note CONVERT specifier:: in an ‘OPEN’ statement or the *note GFORTRAN_CONVERT_UNIT:: environment variable. The maximum number of bytes of user data in a subrecord is 2147483639 (2 GiB - 9) for a four-byte record marker. This limit can be lowered with the ‘-fmax-subrecord-length’ option, although this is rarely useful. If the length of a logical record exceeds this limit, the data is distributed among several subrecords. The absolute of the number stored in the record markers is the number of bytes of user data in the corresponding subrecord. If the leading record marker of a subrecord contains a negative number, another subrecord follows the current one. If the trailing record marker contains a negative number, then there is a preceding subrecord. In the most simple case, with only one subrecord per logical record, both record markers contain the number of bytes of user data in the record. The format for unformatted sequential data can be duplicated using unformatted stream, as shown in the example program for an unformatted record containing a single subrecord: program main use iso_fortran_env, only: int32 implicit none integer(int32) :: i real, dimension(10) :: a, b call random_number(a) open (10,file='test.dat',form='unformatted',access='stream') inquire (iolength=i) a write (10) i, a, i close (10) open (10,file='test.dat',form='unformatted') read (10) b if (all (a == b)) print *,'success!' end program main  File: gfortran.info, Node: Asynchronous I/O, Next: Behavior on integer overflow, Prev: File format of unformatted sequential files, Up: Compiler Characteristics 4.10 Asynchronous I/O ===================== Asynchronous I/O is supported if the program is linked against the POSIX thread library. If that is not the case, all I/O is performed as synchronous. On systems that do not support pthread condition variables, such as AIX, I/O is also performed as synchronous. On some systems, such as Darwin or Solaris, the POSIX thread library is always linked in, so asynchronous I/O is always performed. On other sytems, such as Linux, it is necessary to specify ‘-pthread’, ‘-lpthread’ or ‘-fopenmp’ during the linking step.  File: gfortran.info, Node: Behavior on integer overflow, Prev: Asynchronous I/O, Up: Compiler Characteristics 4.11 Behavior on integer overflow ================================= Integer overflow is prohibited by the Fortran standard. The behavior of gfortran on integer overflow is undefined by default. Traditional code, like linear congruential pseudo-random number generators in old programs that rely on specific, nonstandard behavior may generate unexpected results. The ‘-fsanitize=undefined’ option can be used to detect such code at runtime. It is recommended to use the intrinsic subroutine ‘RANDOM_NUMBER’ for random number generators or, if the old behavior is desired, to use the ‘-fwrapv’ option. Note that this option can impact performance.  File: gfortran.info, Node: Extensions, Next: Mixed-Language Programming, Prev: Compiler Characteristics, Up: Top 5 Extensions ************ The two sections below detail the extensions to standard Fortran that are implemented in GNU Fortran, as well as some of the popular or historically important extensions that are not (or not yet) implemented. For the latter case, we explain the alternatives available to GNU Fortran users, including replacement by standard-conforming code or GNU extensions. * Menu: * Extensions implemented in GNU Fortran:: * Extensions not implemented in GNU Fortran:: * Experimental features for future Fortran versions::  File: gfortran.info, Node: Extensions implemented in GNU Fortran, Next: Extensions not implemented in GNU Fortran, Up: Extensions 5.1 Extensions implemented in GNU Fortran ========================================= GNU Fortran implements a number of extensions over standard Fortran. This chapter contains information on their syntax and meaning. There are currently two categories of GNU Fortran extensions, those that provide functionality beyond that provided by any standard, and those that are supported by GNU Fortran purely for backward compatibility with legacy compilers. By default, ‘-std=gnu’ allows the compiler to accept both types of extensions, but to warn about the use of the latter. Specifying either ‘-std=f95’, ‘-std=f2003’, ‘-std=f2008’, or ‘-std=f2018’ disables both types of extensions, and ‘-std=legacy’ allows both without warning. The special compile flag ‘-fdec’ enables additional compatibility extensions along with those enabled by ‘-std=legacy’. * Menu: * Old-style kind specifications:: * Old-style variable initialization:: * Extensions to namelist:: * X format descriptor without count field:: * Commas in FORMAT specifications:: * Missing period in FORMAT specifications:: * Default widths for F/G/I format descriptors:: * I/O item lists:: * Q exponent-letter:: * BOZ literal constants:: * Real array indices:: * Unary operators:: * Implicitly convert LOGICAL and INTEGER values:: * Hollerith constants support:: * Character conversion:: * Cray pointers:: * CONVERT specifier:: * OpenMP:: * OpenACC:: * Argument list functions:: * Read/Write after EOF marker:: * STRUCTURE and RECORD:: * UNION and MAP:: * Type variants for integer intrinsics:: * AUTOMATIC and STATIC attributes:: * Form feed as whitespace:: * TYPE as an alias for PRINT:: * %LOC as an rvalue:: * .XOR. operator:: * Bitwise logical operators:: * Extended I/O specifiers:: * Legacy PARAMETER statements:: * Default exponents::  File: gfortran.info, Node: Old-style kind specifications, Next: Old-style variable initialization, Up: Extensions implemented in GNU Fortran 5.1.1 Old-style kind specifications ----------------------------------- GNU Fortran allows old-style kind specifications in declarations. These look like: TYPESPEC*SIZE x,y,z where ‘TYPESPEC’ is a basic type (‘INTEGER’, ‘REAL’, etc.), and where SIZE is a byte count corresponding to the storage size of a valid kind for that type. (For ‘COMPLEX’ variables, SIZE is the total size of the real and imaginary parts.) The statement then declares ‘x’, ‘y’ and ‘z’ to be of type ‘TYPESPEC’ with the appropriate kind. This is equivalent to the standard-conforming declaration TYPESPEC(k) x,y,z where ‘k’ is the kind parameter suitable for the intended precision. As kind parameters are implementation-dependent, use the ‘KIND’, ‘SELECTED_INT_KIND’, ‘SELECTED_LOGICAL_KIND’ and ‘SELECTED_REAL_KIND’ intrinsics to retrieve the correct value, for instance ‘REAL*8 x’ can be replaced by: INTEGER, PARAMETER :: dbl = KIND(1.0d0) REAL(KIND=dbl) :: x  File: gfortran.info, Node: Old-style variable initialization, Next: Extensions to namelist, Prev: Old-style kind specifications, Up: Extensions implemented in GNU Fortran 5.1.2 Old-style variable initialization --------------------------------------- GNU Fortran allows old-style initialization of variables of the form: INTEGER i/1/,j/2/ REAL x(2,2) /3*0.,1./ The syntax for the initializers is as for the ‘DATA’ statement, but unlike in a ‘DATA’ statement, an initializer only applies to the variable immediately preceding the initialization. In other words, something like ‘INTEGER I,J/2,3/’ is not valid. This style of initialization is only allowed in declarations without double colons (‘::’); the double colons were introduced in Fortran 90, which also introduced a standard syntax for initializing variables in type declarations. Examples of standard-conforming code equivalent to the above example are: ! Fortran 90 INTEGER :: i = 1, j = 2 REAL :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x)) ! Fortran 77 INTEGER i, j REAL x(2,2) DATA i/1/, j/2/, x/3*0.,1./ Note that variables that are explicitly initialized in declarations or in ‘DATA’ statements automatically acquire the ‘SAVE’ attribute.  File: gfortran.info, Node: Extensions to namelist, Next: X format descriptor without count field, Prev: Old-style variable initialization, Up: Extensions implemented in GNU Fortran 5.1.3 Extensions to namelist ---------------------------- GNU Fortran fully supports the Fortran 95 standard for namelist I/O including array qualifiers, substrings and fully qualified derived types. The output from a namelist write is compatible with namelist read. The output has all names in upper case and indentation to column 1 after the namelist name. The following extensions are permitted: • Old-style use of ‘$’ instead of ‘&’ $MYNML X(:)%Y(2) = 1.0 2.0 3.0 CH(1:4) = "abcd" $END It should be noted that the default terminator is ‘/’ rather than ‘&END’. • Querying of the namelist when inputting from stdin. After at least one space, entering ‘?’ sends to stdout the namelist name and the names of the variables in the namelist: ? &mynml x x%y ch &end Entering ‘=?’ outputs the namelist to stdout, as if ‘WRITE(*,NML = mynml)’ had been called: =? &MYNML X(1)%Y= 0.000000 , 1.000000 , 0.000000 , X(2)%Y= 0.000000 , 2.000000 , 0.000000 , X(3)%Y= 0.000000 , 3.000000 , 0.000000 , CH=abcd, / To aid this dialog, when input is from stdin, errors send their messages to stderr and execution continues, even if ‘IOSTAT’ is set. • ‘PRINT’ namelist is permitted. This causes an error if ‘-std=f95’ is used. PROGRAM test_print REAL, dimension (4) :: x = (/1.0, 2.0, 3.0, 4.0/) NAMELIST /mynml/ x PRINT mynml END PROGRAM test_print • Expanded namelist reads are permitted. This causes an error if ‘-std=f95’ is used. In the following example, the first element of the array is given the value 0.00 and the two succeeding elements are given the values 1.00 and 2.00. &MYNML X(1,1) = 0.00 , 1.00 , 2.00 / When writing a namelist, if no ‘DELIM=’ is specified, by default a double quote is used to delimit character strings. With ‘-std=f95’ or later, the delim status is set to ‘'none'’. Defaulting to quotes ensures that namelists with character strings can be subsequently read back in accurately.  File: gfortran.info, Node: X format descriptor without count field, Next: Commas in FORMAT specifications, Prev: Extensions to namelist, Up: Extensions implemented in GNU Fortran 5.1.4 ‘X’ format descriptor without count field ----------------------------------------------- To support legacy codes, GNU Fortran permits the count field of the ‘X’ edit descriptor in ‘FORMAT’ statements to be omitted. When omitted, the count is implicitly assumed to be one. PRINT 10, 2, 3 10 FORMAT (I1, X, I1)  File: gfortran.info, Node: Commas in FORMAT specifications, Next: Missing period in FORMAT specifications, Prev: X format descriptor without count field, Up: Extensions implemented in GNU Fortran 5.1.5 Commas in ‘FORMAT’ specifications --------------------------------------- To support legacy codes, GNU Fortran allows the comma separator to be omitted immediately before and after character string edit descriptors in ‘FORMAT’ statements. A comma with no following format descriptor is permitted if the ‘-fdec-blank-format-item’ is given on the command line. This is considered non-conforming code and is discouraged. PRINT 10, 2, 3 10 FORMAT ('FOO='I1' BAR='I2) print 20, 5, 6 20 FORMAT (I3, I3,)  File: gfortran.info, Node: Missing period in FORMAT specifications, Next: Default widths for F/G/I format descriptors, Prev: Commas in FORMAT specifications, Up: Extensions implemented in GNU Fortran 5.1.6 Missing period in ‘FORMAT’ specifications ----------------------------------------------- To support legacy codes, GNU Fortran allows missing periods in format specifications if and only if ‘-std=legacy’ is given on the command line. This is considered non-conforming code and is discouraged. REAL :: value READ(*,10) value 10 FORMAT ('F4')  File: gfortran.info, Node: Default widths for F/G/I format descriptors, Next: I/O item lists, Prev: Missing period in FORMAT specifications, Up: Extensions implemented in GNU Fortran 5.1.7 Default widths for ‘F’, ‘G’ and ‘I’ format descriptors ------------------------------------------------------------ To support legacy codes, GNU Fortran allows width to be omitted from format specifications if and only if ‘-fdec-format-defaults’ is given on the command line. Default widths are used. This is considered non-conforming code and is discouraged. REAL :: value1 INTEGER :: value2 WRITE(*,10) value1, value1, value2 10 FORMAT ('F, G, I')  File: gfortran.info, Node: I/O item lists, Next: Q exponent-letter, Prev: Default widths for F/G/I format descriptors, Up: Extensions implemented in GNU Fortran 5.1.8 I/O item lists -------------------- To support legacy codes, GNU Fortran allows the input item list of the ‘READ’ statement, and the output item lists of the ‘WRITE’ and ‘PRINT’ statements, to start with a comma.  File: gfortran.info, Node: Q exponent-letter, Next: BOZ literal constants, Prev: I/O item lists, Up: Extensions implemented in GNU Fortran 5.1.9 ‘Q’ exponent-letter ------------------------- GNU Fortran accepts real literal constants with an exponent-letter of ‘Q’, for example, ‘1.23Q45’. The constant is interpreted as a ‘REAL(16)’ entity on targets that support this type. If the target does not support ‘REAL(16)’ but has a ‘REAL(10)’ type, then the real-literal-constant is interpreted as a ‘REAL(10)’ entity. In the absence of ‘REAL(16)’ and ‘REAL(10)’, an error occurs.  File: gfortran.info, Node: BOZ literal constants, Next: Real array indices, Prev: Q exponent-letter, Up: Extensions implemented in GNU Fortran 5.1.10 BOZ literal constants ---------------------------- Besides decimal constants, Fortran also supports binary (‘b’), octal (‘o’) and hexadecimal (‘z’) integer constants. The syntax is: ‘prefix quote digits quote’, where the prefix is either ‘b’, ‘o’ or ‘z’, quote is either ‘'’ or ‘"’ and the digits are ‘0’ or ‘1’ for binary, between ‘0’ and ‘7’ for octal, and between ‘0’ and ‘F’ for hexadecimal. (Example: ‘b'01011101'’.) Up to Fortran 95, BOZ literal constants were only allowed to initialize integer variables in DATA statements. Since Fortran 2003 BOZ literal constants are also allowed as actual arguments to the ‘REAL’, ‘DBLE’, ‘INT’ and ‘CMPLX’ intrinsic functions. The BOZ literal constant is simply a string of bits, which is padded or truncated as needed, during conversion to a numeric type. The Fortran standard states that the treatment of the sign bit is processor dependent. Gfortran interprets the sign bit as a user would expect. As a deprecated extension, GNU Fortran allows hexadecimal BOZ literal constants to be specified using the ‘X’ prefix. That the BOZ literal constant can also be specified by adding a suffix to the string, for example, ‘Z'ABC'’ and ‘'ABC'X’ are equivalent. Additionally, as extension, BOZ literals are permitted in some contexts outside of ‘DATA’ and the intrinsic functions listed in the Fortran standard. Use ‘-fallow-invalid-boz’ to enable the extension.  File: gfortran.info, Node: Real array indices, Next: Unary operators, Prev: BOZ literal constants, Up: Extensions implemented in GNU Fortran 5.1.11 Real array indices ------------------------- As an extension, GNU Fortran allows the use of ‘REAL’ expressions or variables as array indices.  File: gfortran.info, Node: Unary operators, Next: Implicitly convert LOGICAL and INTEGER values, Prev: Real array indices, Up: Extensions implemented in GNU Fortran 5.1.12 Unary operators ---------------------- As an extension, GNU Fortran allows unary plus and unary minus operators to appear as the second operand of binary arithmetic operators without the need for parenthesis. X = Y * -Z  File: gfortran.info, Node: Implicitly convert LOGICAL and INTEGER values, Next: Hollerith constants support, Prev: Unary operators, Up: Extensions implemented in GNU Fortran 5.1.13 Implicitly convert ‘LOGICAL’ and ‘INTEGER’ values -------------------------------------------------------- As an extension for backwards compatibility with other compilers, GNU Fortran allows the implicit conversion of ‘LOGICAL’ values to ‘INTEGER’ values and vice versa. When converting from a ‘LOGICAL’ to an ‘INTEGER’, ‘.FALSE.’ is interpreted as zero, and ‘.TRUE.’ is interpreted as one. When converting from ‘INTEGER’ to ‘LOGICAL’, the value zero is interpreted as ‘.FALSE.’ and any nonzero value is interpreted as ‘.TRUE.’. LOGICAL :: l l = 1 INTEGER :: i i = .TRUE. However, there is no implicit conversion of ‘INTEGER’ values in ‘if’-statements, nor of ‘LOGICAL’ or ‘INTEGER’ values in I/O operations.  File: gfortran.info, Node: Hollerith constants support, Next: Character conversion, Prev: Implicitly convert LOGICAL and INTEGER values, Up: Extensions implemented in GNU Fortran 5.1.14 Hollerith constants support ---------------------------------- GNU Fortran supports Hollerith constants in assignments, ‘DATA’ statements, function and subroutine arguments. A Hollerith constant is written as a string of characters preceded by an integer constant indicating the character count, and the letter ‘H’ or ‘h’, and stored in bytewise fashion in a numeric (‘INTEGER’, ‘REAL’, or ‘COMPLEX’), ‘LOGICAL’ or ‘CHARACTER’ variable. The constant is padded with spaces or truncated to fit the size of the variable in which it is stored. Examples of valid uses of Hollerith constants: complex*16 x(2) data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/ x(1) = 16HABCDEFGHIJKLMNOP call foo (4h abc) Examples of Hollerith constants: integer*4 a a = 0H ! Invalid, at least one character is needed. a = 4HAB12 ! Valid a = 8H12345678 ! Valid, but the Hollerith constant is truncated. a = 3Hxyz ! Valid, but the Hollerith constant is padded. In general, Hollerith constants were used to provide a rudimentary facility for handling character strings in early Fortran compilers, prior to the introduction of ‘CHARACTER’ variables in Fortran 77; in those cases, the standard-compliant equivalent is to convert the program to use proper character strings. On occasion, there may be a case where the intent is specifically to initialize a numeric variable with a given byte sequence. In these cases, the same result can be obtained by using the ‘TRANSFER’ statement, as in this example. integer(kind=4) :: a a = transfer ("abcd", a) ! equivalent to: a = 4Habcd The use of the ‘-fdec’ option extends support of Hollerith constants to comparisons: integer*4 a a = 4hABCD if (a .ne. 4habcd) then write(*,*) "no match" end if Supported types are numeric (‘INTEGER’, ‘REAL’, or ‘COMPLEX’), and ‘CHARACTER’.  File: gfortran.info, Node: Character conversion, Next: Cray pointers, Prev: Hollerith constants support, Up: Extensions implemented in GNU Fortran 5.1.15 Character conversion --------------------------- Allowing character literals to be used in a similar way to Hollerith constants is a nonstandard extension. This feature is enabled using -fdec-char-conversions and only applies to character literals of ‘kind=1’. Character literals can be used in ‘DATA’ statements and assignments with numeric (‘INTEGER’, ‘REAL’, or ‘COMPLEX’) or ‘LOGICAL’ variables. Like Hollerith constants they are copied bytewise fashion. The constant is padded with spaces or truncated to fit the size of the variable in which it is stored. Examples: integer*4 x data x / 'abcd' / x = 'A' ! Is padded. x = 'ab1234' ! Is truncated.  File: gfortran.info, Node: Cray pointers, Next: CONVERT specifier, Prev: Character conversion, Up: Extensions implemented in GNU Fortran 5.1.16 Cray pointers -------------------- Cray pointers are part of a nonstandard extension that provides a C-like pointer in Fortran. This is accomplished through a pair of variables: an integer "pointer" that holds a memory address, and a "pointee" that is used to dereference the pointer. Pointer/pointee pairs are declared in statements of the form: pointer ( , ) or, pointer ( , ), ( , ), ... The pointer is an integer that is intended to hold a memory address. The pointee may be an array or scalar. If an assumed-size array is permitted within the scoping unit, a pointee can be an assumed-size array. That is, the last dimension may be left unspecified by using a ‘*’ in place of a value. A pointee cannot be an assumed shape array. No space is allocated for the pointee. The pointee may have its type declared before or after the pointer statement, and its array specification (if any) may be declared before, during, or after the pointer statement. The pointer may be declared as an integer prior to the pointer statement. However, some machines have default integer sizes that are different than the size of a pointer, and so the following code is not portable: integer ipt pointer (ipt, iarr) If a pointer is declared with a kind that is too small, the compiler issues a warning; the resulting binary will probably not work correctly, because the memory addresses stored in the pointers may be truncated. It is safer to omit the first line of the above example; if explicit declaration of ‘ipt’'s type is omitted, then the compiler ensures that ‘ipt’ is an integer variable large enough to hold a pointer. Pointer arithmetic is valid with Cray pointers, but it is not the same as C pointer arithmetic. Cray pointers are just ordinary integers, so the user is responsible for determining how many bytes to add to a pointer in order to increment it. Consider the following example: real target(10) real pointee(10) pointer (ipt, pointee) ipt = loc (target) ipt = ipt + 1 The last statement does not set ‘ipt’ to the address of ‘target(1)’, as it would in C pointer arithmetic. Adding ‘1’ to ‘ipt’ just adds one byte to the address stored in ‘ipt’. Any expression involving the pointee is translated to use the value stored in the pointer as the base address. To get the address of elements, this extension provides an intrinsic function ‘LOC()’. The ‘LOC()’ function is equivalent to the ‘&’ operator in C, except the address is cast to an integer type: real ar(10) pointer(ipt, arpte(10)) real arpte ipt = loc(ar) ! Makes arpte is an alias for ar arpte(1) = 1.0 ! Sets ar(1) to 1.0 The pointer can also be set by a call to the ‘MALLOC’ intrinsic (see *note MALLOC::). Cray pointees often are used to alias an existing variable. For example: integer target(10) integer iarr(10) pointer (ipt, iarr) ipt = loc(target) As long as ‘ipt’ remains unchanged, ‘iarr’ is now an alias for ‘target’. The optimizer, however, does not detect this aliasing, so it is unsafe to use ‘iarr’ and ‘target’ simultaneously. Using a pointee in any way that violates the Fortran aliasing rules or assumptions is invalid. It is the user's responsibility to avoid doing this; the compiler works under the assumption that no such aliasing occurs. Cray pointers work correctly when there is no aliasing (i.e., when they are used to access a dynamically allocated block of memory), and also in any routine where a pointee is used, but any variable with which it shares storage is not used. Code that violates these rules may not run as the user intends. This is not a bug in the optimizer; any code that violates the aliasing rules is invalid. (Note that this is not unique to GNU Fortran; any Fortran compiler that supports Cray pointers "incorrectly" optimizes code with invalid aliasing.) There are a number of restrictions on the attributes that can be applied to Cray pointers and pointees. Pointees may not have the ‘ALLOCATABLE’, ‘INTENT’, ‘OPTIONAL’, ‘DUMMY’, ‘TARGET’, ‘INTRINSIC’, or ‘POINTER’ attributes. Pointers may not have the ‘DIMENSION’, ‘POINTER’, ‘TARGET’, ‘ALLOCATABLE’, ‘EXTERNAL’, or ‘INTRINSIC’ attributes, nor may they be function results. Pointees may not occur in more than one pointer statement. A pointee cannot be a pointer. Pointees cannot occur in equivalence, common, or data statements. A Cray pointer may also point to a function or a subroutine. For example, the following excerpt is valid: implicit none external sub pointer (subptr,subpte) external subpte subptr = loc(sub) call subpte() [...] subroutine sub [...] end subroutine sub A pointer may be modified during the course of a program, and this changes the location to which the pointee refers. However, when pointees are passed as arguments, they are treated as ordinary variables in the invoked function. Subsequent changes to the pointer do not change the base address of the array that was passed.  File: gfortran.info, Node: CONVERT specifier, Next: OpenMP, Prev: Cray pointers, Up: Extensions implemented in GNU Fortran 5.1.17 ‘CONVERT’ specifier -------------------------- GNU Fortran allows the conversion of unformatted data between little- and big-endian representation to facilitate moving of data between different systems. The conversion can be indicated with the ‘CONVERT’ specifier on the ‘OPEN’ statement. *Note GFORTRAN_CONVERT_UNIT::, for an alternative way of specifying the data format via an environment variable. Valid values for ‘CONVERT’ on most systems are: ‘CONVERT='NATIVE'’ Use the native format. This is the default. ‘CONVERT='SWAP'’ Swap between little- and big-endian. ‘CONVERT='LITTLE_ENDIAN'’ Use the little-endian representation for unformatted files. ‘CONVERT='BIG_ENDIAN'’ Use the big-endian representation for unformatted files. On POWER systems that support ‘-mabi=ieeelongdouble’, there are additional options, which can be combined with the others with commas. Those are ‘CONVERT='R16_IEEE'’ Use IEEE 128-bit format for ‘REAL(KIND=16)’. ‘CONVERT='R16_IBM'’ Use IBM ‘long double’ format for ‘REAL(KIND=16)’. Using the option could look like this: open(file='big.dat',form='unformatted',access='sequential', & convert='big_endian') The value of the conversion can be queried by using ‘INQUIRE(CONVERT=ch)’. The values returned are ‘'BIG_ENDIAN'’ and ‘'LITTLE_ENDIAN'’. ‘CONVERT’ works between big- and little-endian for ‘INTEGER’ values of all supported kinds and for ‘REAL’ on IEEE systems of kinds 4 and 8. Conversion between different "extended double" types on different architectures such as m68k and x86_64, which GNU Fortran supports as ‘REAL(KIND=10)’ and ‘REAL(KIND=16)’, probably does not work. Note that the values specified via the ‘GFORTRAN_CONVERT_UNIT’ environment variable overrides the ‘CONVERT’ specifier in the ‘OPEN’ statement. This is to give control over data formats to users who do not have the source code of their program available. Using anything but the native representation for unformatted data carries a significant speed overhead. If speed in this area matters to you, it is best if you use this only for data that needs to be portable.  File: gfortran.info, Node: OpenMP, Next: OpenACC, Prev: CONVERT specifier, Up: Extensions implemented in GNU Fortran 5.1.18 OpenMP ------------- OpenMP (Open Multi-Processing) is an application programming interface (API) that supports multi-platform shared memory multiprocessing programming in C/C++ and Fortran on many architectures, including Unix and Microsoft Windows platforms. It consists of a set of compiler directives, library routines, and environment variables that influence run-time behavior. GNU Fortran implements all of the OpenMP Application Program Interface v4.5 (https://openmp.org/specifications/), and many features from later versions of the OpenMP specification. *Note (libgomp)OpenMP Implementation Status::, for more details about currently supported OpenMP features. To enable the processing of the OpenMP directive ‘!$omp’ in free-form source code; the ‘c$omp’, ‘*$omp’ and ‘!$omp’ directives in fixed form; the ‘!$’ conditional compilation sentinels in free form; and the ‘c$’, ‘*$’ and ‘!$’ sentinels in fixed form, ‘gfortran’ needs to be invoked with the ‘-fopenmp’ option. This option also arranges for automatic linking of the OpenMP runtime library. *Note (libgomp)::. The OpenMP Fortran runtime library routines are provided both in a form of a Fortran 90 module named ‘omp_lib’ and in a form of a Fortran ‘include’ file named ‘omp_lib.h’. An example of a parallelized loop taken from Appendix A.1 of the OpenMP Application Program Interface v2.5: SUBROUTINE A1(N, A, B) INTEGER I, N REAL B(N), A(N) !$OMP PARALLEL DO !I is private by default DO I=2,N B(I) = (A(I) + A(I-1)) / 2.0 ENDDO !$OMP END PARALLEL DO END SUBROUTINE A1 *Note (gcc)OpenMP and OpenACC Options::, for additional options useful with ‘-fopenmp’. Please note: • ‘-fopenmp’ implies ‘-frecursive’, i.e., all local arrays are allocated on the stack. When porting existing code to OpenMP, this may lead to surprising results, especially segmentation faults if the stack size is limited. • On glibc-based systems, OpenMP-enabled applications cannot be statically linked due to limitations of the underlying pthreads implementation. It might be possible to get a working solution if ‘-Wl,--whole-archive -lpthread -Wl,--no-whole-archive’ is added to the command line. However, this is not supported by GCC and thus not recommended.  File: gfortran.info, Node: OpenACC, Next: Argument list functions, Prev: OpenMP, Up: Extensions implemented in GNU Fortran 5.1.19 OpenACC -------------- OpenACC is an application programming interface (API) that supports offloading of code to accelerator devices. It consists of a set of compiler directives, library routines, and environment variables that influence run-time behavior. GNU Fortran strives to be compatible with the OpenACC Application Programming Interface v2.6 (https://www.openacc.org/). To enable the processing of the OpenACC directive ‘!$acc’ in free-form source code; the ‘c$acc’, ‘*$acc’ and ‘!$acc’ directives in fixed form; the ‘!$’ conditional compilation sentinels in free form; and the ‘c$’, ‘*$’ and ‘!$’ sentinels in fixed form, ‘gfortran’ needs to be invoked with the ‘-fopenacc’ option. This option also arranges for automatic linking of the OpenACC runtime library. *Note (libgomp)::. The OpenACC Fortran runtime library routines are provided both in a form of a Fortran 90 module named ‘openacc’ and in a form of a Fortran ‘include’ file named ‘openacc_lib.h’. *Note (gcc)OpenMP and OpenACC Options::, for additional options useful with ‘-fopenacc’.  File: gfortran.info, Node: Argument list functions, Next: Read/Write after EOF marker, Prev: OpenACC, Up: Extensions implemented in GNU Fortran 5.1.20 Argument list functions ‘%VAL’, ‘%REF’ and ‘%LOC’ -------------------------------------------------------- GNU Fortran supports argument list functions ‘%VAL’, ‘%REF’ and ‘%LOC’ statements, for backward compatibility with g77. It is recommended that these should be used only for code that is accessing facilities outside of GNU Fortran, such as operating system or windowing facilities. It is best to constrain such uses to isolated portions of a program-portions that deal specifically and exclusively with low-level, system-dependent facilities. Such portions might well provide a portable interface for use by the program as a whole, but are themselves not portable, and should be thoroughly tested each time they are rebuilt using a new compiler or version of a compiler. ‘%VAL’ passes a scalar argument by value, ‘%REF’ passes it by reference and ‘%LOC’ passes its memory location. Since gfortran already passes scalar arguments by reference, ‘%REF’ is in effect a do-nothing. ‘%LOC’ has the same effect as a Fortran pointer. An example of passing an argument by value to a C subroutine foo.: C C prototype void foo_ (float x); C external foo real*4 x x = 3.14159 call foo (%VAL (x)) end For details refer to the g77 manual . Also, ‘c_by_val.f’ and its partner ‘c_by_val.c’ of the GNU Fortran testsuite are worth a look.  File: gfortran.info, Node: Read/Write after EOF marker, Next: STRUCTURE and RECORD, Prev: Argument list functions, Up: Extensions implemented in GNU Fortran 5.1.21 Read/Write after EOF marker ---------------------------------- Some legacy codes rely on allowing ‘READ’ or ‘WRITE’ after the EOF file marker in order to find the end of a file. GNU Fortran normally rejects these codes with a run-time error message and suggests the user consider ‘BACKSPACE’ or ‘REWIND’ to properly position the file before the EOF marker. As an extension, the run-time error may be disabled using -std=legacy.  File: gfortran.info, Node: STRUCTURE and RECORD, Next: UNION and MAP, Prev: Read/Write after EOF marker, Up: Extensions implemented in GNU Fortran 5.1.22 ‘STRUCTURE’ and ‘RECORD’ ------------------------------- Record structures are a pre-Fortran-90 vendor extension to create user-defined aggregate data types. Support for record structures in GNU Fortran can be enabled with the ‘-fdec-structure’ compile flag. If you have a choice, you should instead use Fortran 90's "derived types", which have a different syntax. In many cases, record structures can easily be converted to derived types. To convert, replace ‘STRUCTURE /’STRUCTURE-NAME‘/’ by ‘TYPE’ TYPE-NAME. Additionally, replace ‘RECORD /’STRUCTURE-NAME‘/’ by ‘TYPE(’TYPE-NAME‘)’. Finally, in the component access, replace the period (‘.’) by the percent sign (‘%’). Here is an example of code using the non portable record structure syntax: ! Declaring a structure named ``item'' and containing three fields: ! an integer ID, an description string and a floating-point price. STRUCTURE /item/ INTEGER id CHARACTER(LEN=200) description REAL price END STRUCTURE ! Define two variables, an single record of type ``item'' ! named ``pear'', and an array of items named ``store_catalog'' RECORD /item/ pear, store_catalog(100) ! We can directly access the fields of both variables pear.id = 92316 pear.description = "juicy D'Anjou pear" pear.price = 0.15 store_catalog(7).id = 7831 store_catalog(7).description = "milk bottle" store_catalog(7).price = 1.2 ! We can also manipulate the whole structure store_catalog(12) = pear print *, store_catalog(12) This code can easily be rewritten in the Fortran 90 syntax as following: ! ``STRUCTURE /name/ ... END STRUCTURE'' becomes ! ``TYPE name ... END TYPE'' TYPE item INTEGER id CHARACTER(LEN=200) description REAL price END TYPE ! ``RECORD /name/ variable'' becomes ``TYPE(name) variable'' TYPE(item) pear, store_catalog(100) ! Instead of using a dot (.) to access fields of a record, the ! standard syntax uses a percent sign (%) pear%id = 92316 pear%description = "juicy D'Anjou pear" pear%price = 0.15 store_catalog(7)%id = 7831 store_catalog(7)%description = "milk bottle" store_catalog(7)%price = 1.2 ! Assignments of a whole variable do not change store_catalog(12) = pear print *, store_catalog(12) GNU Fortran implements structures like derived types with the following rules and exceptions: • Structures act like derived types with the ‘SEQUENCE’ attribute. Otherwise they may contain no specifiers. • Structures may contain a special field with the name ‘%FILL’. This creates an anonymous component that cannot be accessed but occupies space just as if a component of the same type was declared in its place, useful for alignment purposes. As an example, the following structure consists of at least sixteen bytes: structure /padded/ character(4) start character(8) %FILL character(4) end end structure • Structures may share names with other symbols. For example, the following is invalid for derived types, but valid for structures: structure /header/ ! ... end structure record /header/ header • Structure types may be declared nested within another parent structure. The syntax is: structure /type-name/ ... structure [//] ... The type name may be omitted, in which case the structure type itself is anonymous, and other structures of the same type cannot be instantiated. The following shows some examples: structure /appointment/ ! nested structure definition: app_time is an array of two 'time' structure /time/ app_time (2) integer(1) hour, minute end structure character(10) memo end structure ! The 'time' structure is still usable record /time/ now now = time(5, 30) ... structure /appointment/ ! anonymous nested structure definition structure start, end integer(1) hour, minute end structure character(10) memo end structure • Structures may contain ‘UNION’ blocks. For more detail see the section on *note UNION and MAP::. • Structures support old-style initialization of components, like those described in *note Old-style variable initialization::. For array initializers, an initializer may contain a repeat specification of the form ‘ * ’. The value of the integer indicates the number of times to repeat the constant initializer when expanding the initializer list.  File: gfortran.info, Node: UNION and MAP, Next: Type variants for integer intrinsics, Prev: STRUCTURE and RECORD, Up: Extensions implemented in GNU Fortran 5.1.23 ‘UNION’ and ‘MAP’ ------------------------ Unions are an old vendor extension which were commonly used with the nonstandard *note STRUCTURE and RECORD:: extensions. Use of ‘UNION’ and ‘MAP’ is automatically enabled with ‘-fdec-structure’. A ‘UNION’ declaration occurs within a structure; within the definition of each union is a number of ‘MAP’ blocks. Each ‘MAP’ shares storage with its sibling maps (in the same union), and the size of the union is the size of the largest map within it, just as with unions in C. The major difference is that component references do not indicate which union or map the component is in (the compiler gets to figure that out). Here is a small example: structure /myunion/ union map character(2) w0, w1, w2 end map map character(6) long end map end union end structure record /myunion/ rec ! After this assignment... rec.long = 'hello!' ! The following is true: ! rec.w0 === 'he' ! rec.w1 === 'll' ! rec.w2 === 'o!' The two maps share memory, and the size of the union is ultimately six bytes: 0 1 2 3 4 5 6 Byte offset ------------------------------- | | | | | | | ------------------------------- ^ W0 ^ W1 ^ W2 ^ \-------/ \-------/ \-------/ ^ LONG ^ \---------------------------/ Following is an example mirroring the layout of an Intel x86_64 register: structure /reg/ union ! U0 ! rax map character(16) rx end map map character(8) rh ! rah union ! U1 map character(8) rl ! ral end map map character(8) ex ! eax end map map character(4) eh ! eah union ! U2 map character(4) el ! eal end map map character(4) x ! ax end map map character(2) h ! ah character(2) l ! al end map end union end map end union end map end union end structure record /reg/ a ! After this assignment... a.rx = 'AAAAAAAA.BBB.C.D' ! The following is true: a.rx === 'AAAAAAAA.BBB.C.D' a.rh === 'AAAAAAAA' a.rl === '.BBB.C.D' a.ex === '.BBB.C.D' a.eh === '.BBB' a.el === '.C.D' a.x === '.C.D' a.h === '.C' a.l === '.D'  File: gfortran.info, Node: Type variants for integer intrinsics, Next: AUTOMATIC and STATIC attributes, Prev: UNION and MAP, Up: Extensions implemented in GNU Fortran 5.1.24 Type variants for integer intrinsics ------------------------------------------- Similar to the D/C prefixes to real functions to specify the input/output types, GNU Fortran offers B/I/J/K prefixes to integer functions for compatibility with DEC programs. The types implied by each are: B - INTEGER(kind=1) I - INTEGER(kind=2) J - INTEGER(kind=4) K - INTEGER(kind=8) GNU Fortran supports these with the flag ‘-fdec-intrinsic-ints’. Intrinsics for which prefixed versions are available and in what form are noted in *note Intrinsic Procedures::. The complete list of supported intrinsics is here: Intrinsic B I J K --------------------------------------------------------------------------- ‘*note ABS::’ ‘BABS’ ‘IIABS’ ‘JIABS’ ‘KIABS’ ‘*note BTEST::’‘BBTEST’ ‘BITEST’ ‘BJTEST’ ‘BKTEST’ ‘*note IAND::’ ‘BIAND’ ‘IIAND’ ‘JIAND’ ‘KIAND’ ‘*note IBCLR::’‘BBCLR’ ‘IIBCLR’ ‘JIBCLR’ ‘KIBCLR’ ‘*note IBITS::’‘BBITS’ ‘IIBITS’ ‘JIBITS’ ‘KIBITS’ ‘*note IBSET::’‘BBSET’ ‘IIBSET’ ‘JIBSET’ ‘KIBSET’ ‘*note IEOR::’ ‘BIEOR’ ‘IIEOR’ ‘JIEOR’ ‘KIEOR’ ‘*note IOR::’ ‘BIOR’ ‘IIOR’ ‘JIOR’ ‘KIOR’ ‘*note ISHFT::’‘BSHFT’ ‘IISHFT’ ‘JISHFT’ ‘KISHFT’ ‘*note ISHFTC::’‘BSHFTC’ ‘IISHFTC’ ‘JISHFTC’ ‘KISHFTC’ ‘*note MOD::’ ‘BMOD’ ‘IMOD’ ‘JMOD’ ‘KMOD’ ‘*note NOT::’ ‘BNOT’ ‘INOT’ ‘JNOT’ ‘KNOT’ ‘*note REAL::’ ‘--’ ‘FLOATI’ ‘FLOATJ’ ‘FLOATK’  File: gfortran.info, Node: AUTOMATIC and STATIC attributes, Next: Form feed as whitespace, Prev: Type variants for integer intrinsics, Up: Extensions implemented in GNU Fortran 5.1.25 ‘AUTOMATIC’ and ‘STATIC’ attributes ------------------------------------------ With ‘-fdec-static’ GNU Fortran supports the DEC extended attributes ‘STATIC’ and ‘AUTOMATIC’ to provide explicit specification of entity storage. These follow the syntax of the Fortran standard ‘SAVE’ attribute. ‘STATIC’ is exactly equivalent to ‘SAVE’, and specifies that an entity should be allocated in static memory. As an example, ‘STATIC’ local variables retain their values across multiple calls to a function. Entities marked ‘AUTOMATIC’ are stack automatic whenever possible. ‘AUTOMATIC’ is the default for local variables smaller than ‘-fmax-stack-var-size’, unless ‘-fno-automatic’ is given. This attribute overrides ‘-fno-automatic’, ‘-fmax-stack-var-size’, and blanket ‘SAVE’ statements. Examples: subroutine f integer, automatic :: i ! automatic variable integer x, y ! static variables save ... endsubroutine subroutine f integer a, b, c, x, y, z static :: x save y automatic z, c ! a, b, c, and z are automatic ! x and y are static endsubroutine ! Compiled with -fno-automatic subroutine f integer a, b, c, d automatic :: a ! a is automatic; b, c, and d are static endsubroutine  File: gfortran.info, Node: Form feed as whitespace, Next: TYPE as an alias for PRINT, Prev: AUTOMATIC and STATIC attributes, Up: Extensions implemented in GNU Fortran 5.1.26 Form feed as whitespace ------------------------------ Historically, legacy compilers allowed insertion of form feed characters ('\f', ASCII 0xC) at the beginning of lines for formatted output to line printers, though the Fortran standard does not mention this. GNU Fortran supports the interpretation of form feed characters in source as whitespace for compatibility.  File: gfortran.info, Node: TYPE as an alias for PRINT, Next: %LOC as an rvalue, Prev: Form feed as whitespace, Up: Extensions implemented in GNU Fortran 5.1.27 ‘TYPE’ as an alias for ‘PRINT’ ------------------------------------- For compatibility, GNU Fortran interprets ‘TYPE’ statements as ‘PRINT’ statements with the flag ‘-fdec’. With this flag asserted, the following two examples are equivalent: TYPE *, 'hello world' PRINT *, 'hello world'  File: gfortran.info, Node: %LOC as an rvalue, Next: .XOR. operator, Prev: TYPE as an alias for PRINT, Up: Extensions implemented in GNU Fortran 5.1.28 %LOC as an rvalue ------------------------ Normally ‘%LOC’ is allowed only in parameter lists. However the intrinsic function ‘LOC’ does the same thing, and is usable as the right-hand-side of assignments. For compatibility, GNU Fortran supports the use of ‘%LOC’ as an alias for the builtin ‘LOC’ with ‘-std=legacy’. With this feature enabled the following two examples are equivalent: integer :: i, l l = %loc(i) call sub(l) integer :: i call sub(%loc(i))  File: gfortran.info, Node: .XOR. operator, Next: Bitwise logical operators, Prev: %LOC as an rvalue, Up: Extensions implemented in GNU Fortran 5.1.29 ‘.XOR.’ operator ----------------------- GNU Fortran supports ‘.XOR.’ as a logical operator with ‘-std=legacy’ for compatibility with legacy code. ‘.XOR.’ is equivalent to ‘.NEQV.’. That is, the output is true if and only if the inputs differ.  File: gfortran.info, Node: Bitwise logical operators, Next: Extended I/O specifiers, Prev: .XOR. operator, Up: Extensions implemented in GNU Fortran 5.1.30 Bitwise logical operators -------------------------------- With ‘-fdec’, GNU Fortran relaxes the type constraints on logical operators to allow integer operands, and performs the corresponding bitwise operation instead. This flag is for compatibility only, and should be avoided in new code. Consider: INTEGER :: i, j i = z'33' j = z'cc' print *, i .AND. j In this example, compiled with ‘-fdec’, GNU Fortran replaces the ‘.AND.’ operation with a call to the intrinsic ‘*note IAND::’ function, yielding the bitwise-and of ‘i’ and ‘j’. Note that this conversion occurs if at least one operand is of integral type. As a result, a logical operand is converted to an integer when the other operand is an integer in a logical operation. In this case, ‘.TRUE.’ is converted to ‘1’ and ‘.FALSE.’ to ‘0’. Here is the mapping of logical operator to bitwise intrinsic used with ‘-fdec’: Operator Intrinsic Bitwise operation -------------------------------------------------------------------------- ‘.NOT.’ ‘NOT’ complement (*note NOT::) ‘.AND.’ ‘IAND’ intersection (*note IAND::) ‘.OR.’ ‘IOR’ union (*note IOR::) ‘.NEQV.’ ‘IEOR’ exclusive or (*note IEOR::) ‘.EQV.’ ‘NOT IEOR’ complement of exclusive or (*note IEOR::)  File: gfortran.info, Node: Extended I/O specifiers, Next: Legacy PARAMETER statements, Prev: Bitwise logical operators, Up: Extensions implemented in GNU Fortran 5.1.31 Extended I/O specifiers ------------------------------ GNU Fortran supports the additional legacy I/O specifiers ‘CARRIAGECONTROL’, ‘READONLY’, and ‘SHARE’ with the compile flag ‘-fdec’, for compatibility. ‘CARRIAGECONTROL’ The ‘CARRIAGECONTROL’ specifier allows a user to control line termination settings between output records for an I/O unit. The specifier has no meaning for readonly files. When ‘CARRIAGECONTROL’ is specified upon opening a unit for formatted writing, the exact ‘CARRIAGECONTROL’ setting determines what characters to write between output records. The syntax is: OPEN(..., CARRIAGECONTROL=cc) where _cc_ is a character expression that evaluates to one of the following values: ‘'LIST'’ One line feed between records (default) ‘'FORTRAN'’ Legacy interpretation of the first character (see below) ‘'NONE'’ No separator between records With ‘CARRIAGECONTROL='FORTRAN'’, when a record is written, the first character of the input record is not written, and instead determines the output record separator as follows: Leading character Meaning Output separating character(s) ---------------------------------------------------------------------------- ‘'+'’ Overprinting Carriage return only ‘'-'’ New line Line feed and carriage return ‘'0'’ Skip line Two line feeds and carriage return ‘'1'’ New page Form feed and carriage return ‘'$'’ Prompting Line feed (no carriage return) ‘CHAR(0)’ Overprinting (no None advance) ‘READONLY’ The ‘READONLY’ specifier may be given upon opening a unit, and is equivalent to specifying ‘ACTION='READ'’, except that the file may not be deleted on close (i.e. ‘CLOSE’ with ‘STATUS="DELETE"’). The syntax is: OPEN(..., READONLY) ‘SHARE’ The ‘SHARE’ specifier allows system-level locking on a unit upon opening it for controlled access from multiple processes/threads. The ‘SHARE’ specifier has several forms: OPEN(..., SHARE=sh) OPEN(..., SHARED) OPEN(..., NOSHARED) Where _sh_ in the first form is a character expression that evaluates to a value as seen in the table below. The latter two forms are aliases for particular values of _sh_: Explicit form Short form Meaning ---------------------------------------------------------------------------- ‘SHARE='DENYRW'’ ‘NOSHARED’ Exclusive (write) lock ‘SHARE='DENYNONE'’ ‘SHARED’ Shared (read) lock In general only one process may hold an exclusive (write) lock for a given file at a time, whereas many processes may hold shared (read) locks for the same file. The behavior of locking may vary with your operating system. On POSIX systems, locking is implemented with ‘fcntl’. Consult your corresponding operating system's manual pages for further details. Locking via ‘SHARE=’ is not supported on other systems.  File: gfortran.info, Node: Legacy PARAMETER statements, Next: Default exponents, Prev: Extended I/O specifiers, Up: Extensions implemented in GNU Fortran 5.1.32 Legacy ‘PARAMETER’ statements ------------------------------------ For compatibility, GNU Fortran supports legacy ‘PARAMETER’ statements without parentheses with ‘-std=legacy’. A warning is emitted if used with ‘-std=gnu’, and an error is acknowledged with a real Fortran standard flag (‘-std=f95’, etc...). These statements take the following form: implicit real (E) parameter e = 2.718282 real c parameter c = 3.0e8  File: gfortran.info, Node: Default exponents, Prev: Legacy PARAMETER statements, Up: Extensions implemented in GNU Fortran 5.1.33 Default exponents ------------------------ For compatibility, GNU Fortran supports a default exponent of zero in real constants with ‘-fdec’. For example, ‘9e’ would be interpreted as ‘9e0’, rather than an error.  File: gfortran.info, Node: Extensions not implemented in GNU Fortran, Next: Experimental features for future Fortran versions, Prev: Extensions implemented in GNU Fortran, Up: Extensions 5.2 Extensions not implemented in GNU Fortran ============================================= The long history of the Fortran language, its wide use and broad userbase, the large number of different compiler vendors and the lack of some features crucial to users in the first standards have lead to the existence of a number of important extensions to the language. While some of the most useful or popular extensions are supported by the GNU Fortran compiler, not all existing extensions are supported. This section aims at listing these extensions and offering advice on how best make code that uses them running with the GNU Fortran compiler. * Menu: * ENCODE and DECODE statements:: * Variable FORMAT expressions:: * Alternate complex function syntax:: * Volatile COMMON blocks:: * OPEN( ... NAME=):: * Q edit descriptor::  File: gfortran.info, Node: ENCODE and DECODE statements, Next: Variable FORMAT expressions, Up: Extensions not implemented in GNU Fortran 5.2.1 ‘ENCODE’ and ‘DECODE’ statements -------------------------------------- GNU Fortran does not support the ‘ENCODE’ and ‘DECODE’ statements. These statements are best replaced by ‘READ’ and ‘WRITE’ statements involving internal files (‘CHARACTER’ variables and arrays), which have been part of the Fortran standard since Fortran 77. For example, replace a code fragment like INTEGER*1 LINE(80) REAL A, B, C c ... Code that sets LINE DECODE (80, 9000, LINE) A, B, C 9000 FORMAT (1X, 3(F10.5)) with the following: CHARACTER(LEN=80) LINE REAL A, B, C c ... Code that sets LINE READ (UNIT=LINE, FMT=9000) A, B, C 9000 FORMAT (1X, 3(F10.5)) Similarly, replace a code fragment like INTEGER*1 LINE(80) REAL A, B, C c ... Code that sets A, B and C ENCODE (80, 9000, LINE) A, B, C 9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5)) with the following: CHARACTER(LEN=80) LINE REAL A, B, C c ... Code that sets A, B and C WRITE (UNIT=LINE, FMT=9000) A, B, C 9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))  File: gfortran.info, Node: Variable FORMAT expressions, Next: Alternate complex function syntax, Prev: ENCODE and DECODE statements, Up: Extensions not implemented in GNU Fortran 5.2.2 Variable ‘FORMAT’ expressions ----------------------------------- A variable ‘FORMAT’ expression is format statement that includes angle brackets enclosing a Fortran expression: ‘FORMAT(I)’. GNU Fortran does not support this legacy extension. The effect of variable format expressions can be reproduced by using the more powerful (and standard) combination of internal output and string formats. For example, replace a code fragment like this: WRITE(6,20) INT1 20 FORMAT(I) with the following: c Variable declaration CHARACTER(LEN=20) FMT c c Other code here... c WRITE(FMT,'("(I", I0, ")")') N+1 WRITE(6,FMT) INT1 or with: c Variable declaration CHARACTER(LEN=20) FMT c c Other code here... c WRITE(FMT,*) N+1 WRITE(6,"(I" // ADJUSTL(FMT) // ")") INT1  File: gfortran.info, Node: Alternate complex function syntax, Next: Volatile COMMON blocks, Prev: Variable FORMAT expressions, Up: Extensions not implemented in GNU Fortran 5.2.3 Alternate complex function syntax --------------------------------------- Some Fortran compilers, including ‘g77’, let the user declare complex functions with the syntax ‘COMPLEX FUNCTION name*16()’, as well as ‘COMPLEX*16 FUNCTION name()’. Both are nonstandard legacy extensions. ‘gfortran’ accepts the latter form, which is more common, but not the former.  File: gfortran.info, Node: Volatile COMMON blocks, Next: OPEN( ... NAME=), Prev: Alternate complex function syntax, Up: Extensions not implemented in GNU Fortran 5.2.4 Volatile ‘COMMON’ blocks ------------------------------ Some Fortran compilers, including ‘g77’, let the user declare ‘COMMON’ with the ‘VOLATILE’ attribute. This is invalid standard Fortran syntax and is not supported by ‘gfortran’. Note that ‘gfortran’ accepts ‘VOLATILE’ variables in ‘COMMON’ blocks since revision 4.3.  File: gfortran.info, Node: OPEN( ... NAME=), Next: Q edit descriptor, Prev: Volatile COMMON blocks, Up: Extensions not implemented in GNU Fortran 5.2.5 ‘OPEN( ... NAME=)’ ------------------------ Some Fortran compilers, including ‘g77’, let the user declare ‘OPEN( ... NAME=)’. This is invalid standard Fortran syntax and is not supported by ‘gfortran’. ‘OPEN( ... NAME=)’ should be replaced with ‘OPEN( ... FILE=)’.  File: gfortran.info, Node: Q edit descriptor, Prev: OPEN( ... NAME=), Up: Extensions not implemented in GNU Fortran 5.2.6 ‘Q’ edit descriptor ------------------------- Some Fortran compilers provide the ‘Q’ edit descriptor, which transfers the number of characters left within an input record into an integer variable. A direct replacement of the ‘Q’ edit descriptor is not available in ‘gfortran’. How to replicate its functionality using standard-conforming code depends on what the intent of the original code is. Options to replace ‘Q’ may be to read the whole line into a character variable and then counting the number of non-blank characters left using ‘LEN_TRIM’. Another method may be to use formatted stream, read the data up to the position where the ‘Q’ descriptor occurred, use ‘INQUIRE’ to get the file position, count the characters up to the next ‘NEW_LINE’ and then start reading from the position marked previously.  File: gfortran.info, Node: Experimental features for future Fortran versions, Prev: Extensions not implemented in GNU Fortran, Up: Extensions 5.3 Experimental features future Fortran versions ================================================= GNU Fortran supports some experimental features that have been proposed and accepted by the J3 standards committee. These exist to give users a chance to try them out, and to provide a reference implementation. As these features have not been included in the worklist for Fortran 202Y by WG5, there is a chance that a version in any upcoming standard will differ from what GNU Fortran currently implements. These features are therefore currently classified as an extension. * Menu: * Unsigned integers::  File: gfortran.info, Node: Unsigned integers, Up: Experimental features for future Fortran versions 5.3.1 Unsigned integers ----------------------- If the ‘-funsigned’ option is given, GNU Fortran supports unsigned integers according to J3/24-116 (https://j3-fortran.org/doc/year/24/24-116.txt). The data type is called ‘UNSIGNED’. For an unsigned type with ‘n’ bits, it implements integer arithmetic modulo ‘2**n’, comparable to the ‘unsigned’ data type in C. The data type has ‘KIND’ numbers comparable to other Fortran data types, which can be selected via the ‘SELECTED_UNSIGNED_KIND’ function. Mixed arithmetic, comparisons and assignment between ‘UNSIGNED’ and other types are only possible via explicit conversion. Conversion from ‘UNSIGNED’ to other types is done via type conversion functions like ‘INT’ or ‘REAL’. Conversion from other types to ‘UNSIGNED’ is done via ‘UINT’. Unsigned variables cannot be used as index variables in ‘DO’ loops or as array indices. Unsigned numbers have a trailing ‘u’ as suffix, optionally followed by a ‘KIND’ number separated by an underscore. Input and output can be done using the ‘I’, ‘B’, ‘O’ and ‘Z’ descriptors, plus unformatted I/O. Here is a small, somewhat contrived example of their use: program main use iso_fortran_env, only : uint64 unsigned(kind=uint64) :: v v = huge(v) - 32u_uint64 print *,v end program main which outputs the number 18446744073709551583. Arithmetic operations work on unsigned integers, also for exponentiation. As an extension to J3/24-116.txt, unary minus and exponentiation of unsigned integers are permitted unless ‘-pedantic’ is in force. In intrinsic procedures, unsigned arguments are typically permitted for arguments for the data to be processed, analogous to the use of ‘REAL’ arguments. Unsigned values are prohibited as index variables in ‘DO’ loops and as array indices. Unsigned numbers can be read and written using list-directed, formatted and unformatted I/O. For formatted I/O, the ‘B’, ‘I’, ‘O’ and ‘Z’ descriptors are valid. Negative values and values that would overflow are rejected with ‘-pedantic’. ‘SELECT CASE’ is supported for unsigned integers. The following intrinsics take unsigned arguments: • ‘BGE’, *note BGE:: • ‘BGT’, *note BGT:: • ‘BIT_SIZE’, *note BIT_SIZE:: • ‘BLE’, *note BLE:: • ‘BLT’, *note BLT:: • ‘CMPLX’, *note CMPLX:: • ‘CSHIFT’, *note CSHIFT:: • ‘DIGITS’, *note DIGITS:: • ‘DOT_PRODUCT’, *note DOT_PRODUCT:: • ‘DSHIFTL’, *note DSHIFTL:: • ‘DSHIFTR’, *note DSHIFTR:: • ‘EOSHIFT’, *note EOSHIFT:: • ‘FINDLOC’, *note FINDLOC:: • ‘HUGE’, *note HUGE:: • ‘IALL’, *note IALL:: • ‘IAND’, *note IAND:: • ‘IANY’, *note IANY:: • ‘IBCLR’, *note IBCLR:: • ‘IBITS’, *note IBITS:: • ‘IBSET’, *note IBSET:: • ‘IEOR’, *note IEOR:: • ‘INT’, *note INT:: • ‘IOR’, *note IOR:: • ‘IPARITY’, *note IPARITY:: • ‘ISHFT’, *note ISHFT:: • ‘ISHFTC’, *note ISHFTC:: • ‘MATMUL’, *note MATMUL:: • ‘MAX’, *note MAX:: • ‘MAXLOC’, *note MAXLOC:: • ‘MAXVAL’, *note MAXVAL:: • ‘MERGE’, *note MERGE:: • ‘MERGE_BITS’, *note MERGE_BITS:: • ‘MIN’, *note MIN:: • ‘MINLOC’, *note MINLOC:: • ‘MINVAL’, *note MINVAL:: • ‘MOD’, *note MOD:: • ‘MODULO’, *note MODULO:: • ‘MVBITS’, *note MVBITS:: • ‘NOT’, *note NOT:: • ‘OUT_OF_RANGE’, *note OUT_OF_RANGE:: • ‘PRODUCT’, *note PRODUCT:: • ‘RANDOM_NUMBER’, *note RANDOM_NUMBER:: • ‘RANGE’, *note RANGE:: • ‘REAL’, *note REAL:: • ‘SHIFTA’, *note SHIFTA:: • ‘SHIFTL’, *note SHIFTL:: • ‘SHIFTR’, *note SHIFTR:: • ‘SUM’, *note SUM:: • ‘TRANSPOSE’, *note TRANSPOSE:: • ‘TRANSFER’, *note TRANSFER:: The following intrinsics are enabled with ‘-funsigned’: • ‘UINT’, *note UINT:: • ‘UMASKL’, *note UMASKL:: • ‘UMASKR’, *note UMASKR:: • ‘SELECTED_UNSIGNED_KIND’, *note SELECTED_UNSIGNED_KIND:: The following constants have been added to the intrinsic ‘ISO_C_BINDING’ module: ‘c_unsigned’, ‘c_unsigned_short’, ‘c_unsigned_char’, ‘c_unsigned_long’, ‘c_unsigned_long_long’, ‘c_uintmax_t’, ‘c_uint8_t’, ‘c_uint16_t’, ‘c_uint32_t’, ‘c_uint64_t’, ‘c_uint128_t’, ‘c_uint_fast8_t’, ‘c_uint_fast16_t’, ‘c_uint_fast32_t’, ‘c_uint_fast64_t’, ‘c_uint_fast128_t’, ‘c_uint_least8_t’, ‘c_uint_least16_t’, ‘c_uint_least32_t’, ‘c_uint_least64_t’ and ‘c_uint_least128_t’. The following constants have been added to the intrinsic ‘ISO_FORTRAN_ENV’ module: ‘uint8’, ‘uint16’, ‘uint32’ and ‘uint64’.  File: gfortran.info, Node: Mixed-Language Programming, Next: Coarray Programming, Prev: Extensions, Up: Top 6 Mixed-Language Programming **************************** * Menu: * Interoperability with C:: * GNU Fortran Compiler Directives:: * Non-Fortran Main Program:: * Naming and argument-passing conventions:: This chapter is about mixed-language interoperability, but also applies if you link Fortran code compiled by different compilers. In most cases, use of the C Binding features of the Fortran 2003 and later standards is sufficient. For example, it is possible to mix Fortran code with C++ code as well as C, if you declare the interface functions as ‘extern "C"’ on the C++ side and ‘BIND(C)’ on the Fortran side, and follow the rules for interoperability with C. Note that you cannot manipulate C++ class objects in Fortran or vice versa except as opaque pointers. You can use the ‘gfortran’ command to link both Fortran and non-Fortran code into the same program, or you can use ‘gcc’ or ‘g++’ if you also add an explicit ‘-lgfortran’ option to link with the Fortran library. If your main program is written in C or some other language instead of Fortran, see *note Non-Fortran Main Program::, below.  File: gfortran.info, Node: Interoperability with C, Next: GNU Fortran Compiler Directives, Up: Mixed-Language Programming 6.1 Interoperability with C =========================== * Menu: * Intrinsic Types:: * Derived Types and struct:: * Interoperable Global Variables:: * Interoperable Subroutines and Functions:: * Working with C Pointers:: * Further Interoperability of Fortran with C:: * Generating C prototypes from Fortran:: Since Fortran 2003 (ISO/IEC 1539-1:2004(E)) there is a standardized way to generate procedure and derived-type declarations and global variables that are interoperable with C (ISO/IEC 9899:1999). The ‘BIND(C)’ attribute has been added to inform the compiler that a symbol shall be interoperable with C; also, some constraints are added. Note, however, that not all C features have a Fortran equivalent or vice versa. For instance, neither C's unsigned integers nor C's functions with variable number of arguments have an equivalent in Fortran. Note that array dimensions are reversely ordered in C and that arrays in C always start with index 0 while in Fortran they start by default with 1. Thus, an array declaration ‘A(n,m)’ in Fortran matches ‘A[m][n]’ in C and accessing the element ‘A(i,j)’ matches ‘A[j-1][i-1]’. The element following ‘A(i,j)’ (C: ‘A[j-1][i-1]’; assuming i < n) in memory is ‘A(i+1,j)’ (C: ‘A[j-1][i]’).  File: gfortran.info, Node: Intrinsic Types, Next: Derived Types and struct, Up: Interoperability with C 6.1.1 Intrinsic Types --------------------- In order to ensure that exactly the same variable type and kind is used in C and Fortran, you should use the named constants for kind parameters that are defined in the ‘ISO_C_BINDING’ intrinsic module. That module contains named constants of character type representing the escaped special characters in C, such as newline. For a list of the constants, see *note ISO_C_BINDING::. For logical types, please note that the Fortran standard only guarantees interoperability between C99's ‘_Bool’ and Fortran's ‘C_Bool’-kind logicals and C99 defines that ‘true’ has the value 1 and ‘false’ the value 0. Using any other integer value with GNU Fortran's ‘LOGICAL’ (with any kind parameter) gives an undefined result. (Passing other integer values than 0 and 1 to GCC's ‘_Bool’ is also undefined, unless the integer is explicitly or implicitly casted to ‘_Bool’.)  File: gfortran.info, Node: Derived Types and struct, Next: Interoperable Global Variables, Prev: Intrinsic Types, Up: Interoperability with C 6.1.2 Derived Types and struct ------------------------------ For compatibility of derived types with ‘struct’, use the ‘BIND(C)’ attribute in the type declaration. For instance, the following type declaration USE ISO_C_BINDING TYPE, BIND(C) :: myType INTEGER(C_INT) :: i1, i2 INTEGER(C_SIGNED_CHAR) :: i3 REAL(C_DOUBLE) :: d1 COMPLEX(C_FLOAT_COMPLEX) :: c1 CHARACTER(KIND=C_CHAR) :: str(5) END TYPE matches the following ‘struct’ declaration in C struct { int i1, i2; /* Note: "char" might be signed or unsigned. */ signed char i3; double d1; float _Complex c1; char str[5]; } myType; Derived types with the C binding attribute shall not have the ‘sequence’ attribute, type parameters, the ‘extends’ attribute, nor type-bound procedures. Every component must be of interoperable type and kind and may not have the ‘pointer’ or ‘allocatable’ attribute. The names of the components are irrelevant for interoperability. As there exist no direct Fortran equivalents, neither unions nor structs with bit field or variable-length array members are interoperable.  File: gfortran.info, Node: Interoperable Global Variables, Next: Interoperable Subroutines and Functions, Prev: Derived Types and struct, Up: Interoperability with C 6.1.3 Interoperable Global Variables ------------------------------------ Variables can be made accessible from C using the C binding attribute, optionally together with specifying a binding name. Those variables have to be declared in the declaration part of a ‘MODULE’, be of interoperable type, and have neither the ‘pointer’ nor the ‘allocatable’ attribute. MODULE m USE myType_module USE ISO_C_BINDING integer(C_INT), bind(C, name="_MyProject_flags") :: global_flag type(myType), bind(C) :: tp END MODULE Here, ‘_MyProject_flags’ is the case-sensitive name of the variable as seen from C programs while ‘global_flag’ is the case-insensitive name as seen from Fortran. If no binding name is specified, as for TP, the C binding name is the (lowercase) Fortran binding name. If a binding name is specified, only a single variable may be after the double colon. Note of warning: You cannot use a global variable to access ERRNO of the C library as the C standard allows it to be a macro. Use the ‘IERRNO’ intrinsic (GNU extension) instead.  File: gfortran.info, Node: Interoperable Subroutines and Functions, Next: Working with C Pointers, Prev: Interoperable Global Variables, Up: Interoperability with C 6.1.4 Interoperable Subroutines and Functions --------------------------------------------- Subroutines and functions have to have the ‘BIND(C)’ attribute to be compatible with C. The dummy argument declaration is relatively straightforward. However, one needs to be careful because C uses call-by-value by default while Fortran behaves usually similar to call-by-reference. Furthermore, strings and pointers are handled differently. To pass a variable by value, use the ‘VALUE’ attribute. Thus, the following C prototype int func(int i, int *j) matches the Fortran declaration integer(c_int) function func(i,j) use iso_c_binding, only: c_int integer(c_int), VALUE :: i integer(c_int) :: j Note that pointer arguments also frequently need the ‘VALUE’ attribute, see *note Working with C Pointers::. Strings are handled quite differently in C and Fortran. In C a string is a ‘NUL’-terminated array of characters while in Fortran each string has a length associated with it and is thus not terminated (by e.g. ‘NUL’). For example, if you want to use the following C function, #include void print_C(char *string) /* equivalent: char string[] */ { printf("%s\n", string); } to print "Hello World" from Fortran, you can call it using use iso_c_binding, only: C_CHAR, C_NULL_CHAR interface subroutine print_c(string) bind(C, name="print_C") use iso_c_binding, only: c_char character(kind=c_char) :: string(*) end subroutine print_c end interface call print_c(C_CHAR_"Hello World"//C_NULL_CHAR) As the example shows, you need to ensure that the string is ‘NUL’ terminated. Additionally, the dummy argument STRING of ‘print_C’ is a length-one assumed-size array; using ‘character(len=*)’ is not allowed. The example above uses ‘c_char_"Hello World"’ to ensure the string literal has the right type; typically the default character kind and ‘c_char’ are the same and thus ‘"Hello World"’ is equivalent. However, the standard does not guarantee this. The use of strings is now further illustrated using the C library function ‘strncpy’, whose prototype is char *strncpy(char *restrict s1, const char *restrict s2, size_t n); The function ‘strncpy’ copies at most N characters from string S2 to S1 and returns S1. In the following example, we ignore the return value: use iso_c_binding implicit none character(len=30) :: str,str2 interface ! Ignore the return value of strncpy -> subroutine ! "restrict" is always assumed if we do not pass a pointer subroutine strncpy(dest, src, n) bind(C) import character(kind=c_char), intent(out) :: dest(*) character(kind=c_char), intent(in) :: src(*) integer(c_size_t), value, intent(in) :: n end subroutine strncpy end interface str = repeat('X',30) ! Initialize whole string with 'X' call strncpy(str, c_char_"Hello World"//C_NULL_CHAR, & len(c_char_"Hello World",kind=c_size_t)) print '(a)', str ! prints: "Hello WorldXXXXXXXXXXXXXXXXXXX" end The intrinsic procedures are described in *note Intrinsic Procedures::.  File: gfortran.info, Node: Working with C Pointers, Next: Further Interoperability of Fortran with C, Prev: Interoperable Subroutines and Functions, Up: Interoperability with C 6.1.5 Working with C Pointers ----------------------------- C pointers are represented in Fortran via the special opaque derived type ‘type(c_ptr)’ (with private components). C pointers are distinct from Fortran objects with the ‘POINTER’ attribute. Thus one needs to use intrinsic conversion procedures to convert from or to C pointers. For some applications, using an assumed type (‘TYPE(*)’) can be an alternative to a C pointer, and you can also use library routines to access Fortran pointers from C. See *note Further Interoperability of Fortran with C::. Here is an example of using C pointers in Fortran: use iso_c_binding type(c_ptr) :: cptr1, cptr2 integer, target :: array(7), scalar integer, pointer :: pa(:), ps cptr1 = c_loc(array(1)) ! The programmer needs to ensure that the ! array is contiguous if required by the C ! procedure cptr2 = c_loc(scalar) call c_f_pointer(cptr2, ps) call c_f_pointer(cptr2, pa, shape=[7]) When converting C to Fortran arrays, the one-dimensional ‘SHAPE’ argument has to be passed. If a pointer is a dummy argument of an interoperable procedure, it usually has to be declared using the ‘VALUE’ attribute. ‘void*’ matches ‘TYPE(C_PTR), VALUE’, while ‘TYPE(C_PTR)’ alone matches ‘void**’. Procedure pointers are handled analogously to pointers; the C type is ‘TYPE(C_FUNPTR)’ and the intrinsic conversion procedures are ‘C_F_PROCPOINTER’ and ‘C_FUNLOC’. Let us consider two examples of actually passing a procedure pointer from C to Fortran and vice versa. Note that these examples are also very similar to passing ordinary pointers between both languages. First, consider this code in C: /* Procedure implemented in Fortran. */ void get_values (void (*)(double)); /* Call-back routine we want called from Fortran. */ void print_it (double x) { printf ("Number is %f.\n", x); } /* Call Fortran routine and pass call-back to it. */ void foobar () { get_values (&print_it); } A matching implementation for ‘get_values’ in Fortran that correctly receives the procedure pointer from C and is able to call it, is given in the following ‘MODULE’: MODULE m IMPLICIT NONE ! Define interface of call-back routine. ABSTRACT INTERFACE SUBROUTINE callback (x) USE, INTRINSIC :: ISO_C_BINDING REAL(KIND=C_DOUBLE), INTENT(IN), VALUE :: x END SUBROUTINE callback END INTERFACE CONTAINS ! Define C-bound procedure. SUBROUTINE get_values (cproc) BIND(C) USE, INTRINSIC :: ISO_C_BINDING TYPE(C_FUNPTR), INTENT(IN), VALUE :: cproc PROCEDURE(callback), POINTER :: proc ! Convert C to Fortran procedure pointer. CALL C_F_PROCPOINTER (cproc, proc) ! Call it. CALL proc (1.0_C_DOUBLE) CALL proc (-42.0_C_DOUBLE) CALL proc (18.12_C_DOUBLE) END SUBROUTINE get_values END MODULE m Next, we want to call a C routine that expects a procedure pointer argument and pass it a Fortran procedure (that clearly must be interoperable!). Again, the C function may be: int call_it (int (*func)(int), int arg) { return func (arg); } It can be used as in the following Fortran code: MODULE m USE, INTRINSIC :: ISO_C_BINDING IMPLICIT NONE ! Define interface of C function. INTERFACE INTEGER(KIND=C_INT) FUNCTION call_it (func, arg) BIND(C) USE, INTRINSIC :: ISO_C_BINDING TYPE(C_FUNPTR), INTENT(IN), VALUE :: func INTEGER(KIND=C_INT), INTENT(IN), VALUE :: arg END FUNCTION call_it END INTERFACE CONTAINS ! Define procedure passed to C function. ! It must be interoperable! INTEGER(KIND=C_INT) FUNCTION double_it (arg) BIND(C) INTEGER(KIND=C_INT), INTENT(IN), VALUE :: arg double_it = arg + arg END FUNCTION double_it ! Call C function. SUBROUTINE foobar () TYPE(C_FUNPTR) :: cproc INTEGER(KIND=C_INT) :: i ! Get C procedure pointer. cproc = C_FUNLOC (double_it) ! Use it. DO i = 1_C_INT, 10_C_INT PRINT *, call_it (cproc, i) END DO END SUBROUTINE foobar END MODULE m  File: gfortran.info, Node: Further Interoperability of Fortran with C, Next: Generating C prototypes from Fortran, Prev: Working with C Pointers, Up: Interoperability with C 6.1.6 Further Interoperability of Fortran with C ------------------------------------------------ GNU Fortran implements the Technical Specification ISO/IEC TS 29113:2012, which extends the interoperability support of Fortran 2003 and Fortran 2008 and is now part of the 2018 Fortran standard. Besides removing some restrictions and constraints, the Technical Specification adds assumed-type (‘TYPE(*)’) and assumed-rank (‘DIMENSION(..)’) variables and allows for interoperability of assumed-shape, assumed-rank, and deferred-shape arrays, as well as allocatables and pointers. Objects of these types are passed to ‘BIND(C)’ functions as descriptors with a standard interface, declared in the header file ‘’. Note: Currently, GNU Fortran does not use internally the array descriptor (dope vector) as specified in the Technical Specification, but uses an array descriptor with different fields in functions without the ‘BIND(C)’ attribute. Arguments to functions marked ‘BIND(C)’ are converted to the specified form. If you need to access GNU Fortran's internal array descriptor, you can use the Chasm Language Interoperability Tools, .  File: gfortran.info, Node: Generating C prototypes from Fortran, Prev: Further Interoperability of Fortran with C, Up: Interoperability with C 6.1.7 Generating C prototypes from Fortran ------------------------------------------ The options ‘-fc-prototypes’ can be used to write out C declatations and function prototypes for ‘BIND(C)’ entities. The same can be done for writing out prototypes for external procedures using ‘-fc-prototypes-external’, *note Interoperability Options::. Standard Fortran does not specify an interoperable type for C's ‘unsigned’ integer types. For interoperability with unsigned types, GNU Fortran provides unsigned integers, *note Unsigned integers::.  File: gfortran.info, Node: GNU Fortran Compiler Directives, Next: Non-Fortran Main Program, Prev: Interoperability with C, Up: Mixed-Language Programming 6.2 GNU Fortran Compiler Directives =================================== * Menu: * ATTRIBUTES directive:: * UNROLL directive:: * BUILTIN directive:: * IVDEP directive:: * VECTOR directive:: * NOVECTOR directive::  File: gfortran.info, Node: ATTRIBUTES directive, Next: UNROLL directive, Up: GNU Fortran Compiler Directives 6.2.1 ‘ATTRIBUTES’ directive ---------------------------- The Fortran standard describes how a conforming program shall behave; however, the exact implementation is not standardized. In order to allow the user to choose specific implementation details, compiler directives can be used to set attributes of variables and procedures that are not part of the standard. Whether a given attribute is supported and its exact effects depend on both the operating system and on the processor; see *note C Extensions: (gcc)Top. for details. For procedures and procedure pointers, the following attributes can be used to change the calling convention: • ‘CDECL’ - standard C calling convention • ‘STDCALL’ - convention where the called procedure pops the stack • ‘FASTCALL’ - part of the arguments are passed via registers instead using the stack Besides changing the calling convention, the attributes also influence the decoration of the symbol name, e.g., by a leading underscore or by a trailing at-sign followed by the number of bytes on the stack. When assigning a procedure to a procedure pointer, both should use the same calling convention. On some systems, procedures and global variables (module variables and ‘COMMON’ blocks) need special handling to be accessible when they are in a shared library. The following attributes are available: • ‘DLLEXPORT’ - provide a global pointer to a pointer in the DLL • ‘DLLIMPORT’ - reference the function or variable using a global pointer For dummy arguments, the ‘NO_ARG_CHECK’ attribute can be used; in other compilers, it is also known as ‘IGNORE_TKR’. For dummy arguments with this attribute actual arguments of any type and kind (similar to ‘TYPE(*)’), scalars and arrays of any rank (no equivalent in Fortran standard) are accepted. As with ‘TYPE(*)’, the argument is unlimited polymorphic and no type information is available. Additionally, the argument may only be passed to dummy arguments with the ‘NO_ARG_CHECK’ attribute and as argument to the ‘PRESENT’ intrinsic function and to ‘C_LOC’ of the ‘ISO_C_BINDING’ module. Variables with ‘NO_ARG_CHECK’ attribute shall be of assumed-type (‘TYPE(*)’; recommended) or of type ‘INTEGER’, ‘LOGICAL’, ‘REAL’ or ‘COMPLEX’. They shall not have the ‘ALLOCATE’, ‘CODIMENSION’, ‘INTENT(OUT)’, ‘POINTER’ or ‘VALUE’ attribute; furthermore, they shall be either scalar or of assumed-size (‘dimension(*)’). As ‘TYPE(*)’, the ‘NO_ARG_CHECK’ attribute requires an explicit interface. • ‘NO_ARG_CHECK’ - disable the type, kind and rank checking • ‘DEPRECATED’ - print a warning when using a such-tagged deprecated procedure, variable or parameter; the warning can be suppressed with ‘-Wno-deprecated-declarations’. • ‘NOINLINE’ - prevent inlining given function. • ‘NORETURN’ - add a hint that a given function cannot return. • ‘WEAK’ - emit the declaration of an external symbol as a weak symbol rather than a global. This is primarily useful in defining library functions that can be overridden in user code, though it can also be used with non-function declarations. The overriding symbol must have the same type as the weak symbol. The attributes are specified using the syntax ‘!GCC$ ATTRIBUTES’ ATTRIBUTE-LIST ‘::’ VARIABLE-LIST where in free-form source code only whitespace is allowed before ‘!GCC$’ and in fixed-form source code ‘!GCC$’, ‘cGCC$’ or ‘*GCC$’ shall start in the first column. For procedures, the compiler directives shall be placed into the body of the procedure; for variables and procedure pointers, they shall be in the same declaration part as the variable or procedure pointer.  File: gfortran.info, Node: UNROLL directive, Next: BUILTIN directive, Prev: ATTRIBUTES directive, Up: GNU Fortran Compiler Directives 6.2.2 ‘UNROLL’ directive ------------------------ The syntax of the directive is ‘!GCC$ unroll N’ You can use this directive to control how many times a loop should be unrolled. It must be placed immediately before a ‘DO’ loop and applies only to the loop that follows. N is an integer constant specifying the unrolling factor. The values of 0 and 1 block any unrolling of the loop. For ‘DO CONCURRENT’ constructs the unrolling specification applies only to the first loop control variable.  File: gfortran.info, Node: BUILTIN directive, Next: IVDEP directive, Prev: UNROLL directive, Up: GNU Fortran Compiler Directives 6.2.3 ‘BUILTIN’ directive ------------------------- The syntax of the directive is ‘!GCC$ BUILTIN (B) attributes simd FLAGS IF('target')’ You can use this directive to define which middle-end built-ins provide vector implementations. B is name of the middle-end built-in. FLAGS are optional and must be either ‘(inbranch)’ or ‘(notinbranch)’. ‘IF’ statement is optional and is used to filter multilib ABIs for the built-in that should be vectorized. Example usage: !GCC$ builtin (sinf) attributes simd (notinbranch) if('x86_64') The purpose of the directive is to provide an API among the GCC compiler and the GNU C Library which would define vector implementations of math routines.  File: gfortran.info, Node: IVDEP directive, Next: VECTOR directive, Prev: BUILTIN directive, Up: GNU Fortran Compiler Directives 6.2.4 ‘IVDEP’ directive ----------------------- The syntax of the directive is ‘!GCC$ ivdep’ This directive tells the compiler to ignore vector dependencies in the following loop. It must be placed immediately before a ‘DO’ loop and applies only to the loop that follows. Sometimes the compiler may not have sufficient information to decide whether a particular loop is vectorizable due to potential dependencies between iterations. The purpose of the directive is to tell the compiler that vectorization is safe. For ‘DO CONCURRENT’ constructs this annotation is implicit to all loop control variables. This directive is intended for annotation of existing code. For new code it is recommended to consider OpenMP SIMD directives as potential alternative.  File: gfortran.info, Node: VECTOR directive, Next: NOVECTOR directive, Prev: IVDEP directive, Up: GNU Fortran Compiler Directives 6.2.5 ‘VECTOR’ directive ------------------------ The syntax of the directive is ‘!GCC$ vector’ This directive tells the compiler to vectorize the following loop. It must be placed immediately before a ‘DO’ loop and applies only to the loop that follows. For ‘DO CONCURRENT’ constructs this annotation applies to all loops specified in the concurrent header.  File: gfortran.info, Node: NOVECTOR directive, Prev: VECTOR directive, Up: GNU Fortran Compiler Directives 6.2.6 ‘NOVECTOR’ directive -------------------------- The syntax of the directive is ‘!GCC$ novector’ This directive tells the compiler to not vectorize the following loop. It must be placed immediately before a ‘DO’ loop and applies only to the loop that follows. For ‘DO CONCURRENT’ constructs this annotation applies to all loops specified in the concurrent header.  File: gfortran.info, Node: Non-Fortran Main Program, Next: Naming and argument-passing conventions, Prev: GNU Fortran Compiler Directives, Up: Mixed-Language Programming 6.3 Non-Fortran Main Program ============================ * Menu: * _gfortran_set_args:: Save command-line arguments * _gfortran_set_options:: Set library option flags * _gfortran_set_convert:: Set endian conversion * _gfortran_set_record_marker:: Set length of record markers * _gfortran_set_fpe:: Set when a Floating Point Exception should be raised * _gfortran_set_max_subrecord_length:: Set subrecord length Even if you are doing mixed-language programming, it is very likely that you do not need to know or use the information in this section. Since it is about the internal structure of GNU Fortran, it may also change in GCC minor releases. When you compile a ‘PROGRAM’ with GNU Fortran, a function with the name ‘main’ (in the symbol table of the object file) is generated, which initializes the libgfortran library and then calls the actual program that uses the name ‘MAIN__’, for historic reasons. If you link GNU Fortran compiled procedures to, e.g., a C or C++ program or to a Fortran program compiled by a different compiler, the libgfortran library is not initialized and thus a few intrinsic procedures do not work properly, e.g. those for obtaining the command-line arguments. Therefore, if your ‘PROGRAM’ is not compiled with GNU Fortran and the GNU Fortran compiled procedures require intrinsics relying on the library initialization, you need to initialize the library yourself. Using the default options, gfortran calls ‘_gfortran_set_args’ and ‘_gfortran_set_options’. The initialization of the former is needed if the called procedures access the command line (and for backtracing); the latter sets some flags based on the standard chosen or to enable backtracing. In typical programs, it is not necessary to call any initialization function. If your ‘PROGRAM’ is compiled with GNU Fortran, you shall not call any of the following functions. The libgfortran initialization functions are shown in C syntax but using C bindings they are also accessible from Fortran.  File: gfortran.info, Node: _gfortran_set_args, Next: _gfortran_set_options, Up: Non-Fortran Main Program 6.3.1 ‘_gfortran_set_args’ -- Save command-line arguments --------------------------------------------------------- _Synopsis_: ‘void _gfortran_set_args (int argc, char *argv[])’ _Description_: ‘_gfortran_set_args’ saves the command-line arguments; this initialization is required if any of the command-line intrinsics is called. Additionally, it shall be called if backtracing is enabled (see ‘_gfortran_set_options’). _Arguments_: ARGC number of command line argument strings ARGV the command-line argument strings; argv[0] is the pathname of the executable itself. _Example_: int main (int argc, char *argv[]) { /* Initialize libgfortran. */ _gfortran_set_args (argc, argv); return 0; }  File: gfortran.info, Node: _gfortran_set_options, Next: _gfortran_set_convert, Prev: _gfortran_set_args, Up: Non-Fortran Main Program 6.3.2 ‘_gfortran_set_options’ -- Set library option flags --------------------------------------------------------- _Synopsis_: ‘void _gfortran_set_options (int num, int options[])’ _Description_: ‘_gfortran_set_options’ sets several flags related to the Fortran standard to be used, whether backtracing should be enabled and whether range checks should be performed. The syntax allows for upward compatibility since the number of passed flags is specified; for non-passed flags, the default value is used. See also *note Code Gen Options::. Please note that not all flags are actually used. _Arguments_: NUM number of options passed ARGV The list of flag values _option flag list_: OPTION[0] Allowed standard; can give run-time errors if e.g. an input-output edit descriptor is invalid in a given standard. Possible values are (bitwise or-ed) ‘GFC_STD_F77’ (1), ‘GFC_STD_F95_OBS’ (2), ‘GFC_STD_F95_DEL’ (4), ‘GFC_STD_F95’ (8), ‘GFC_STD_F2003’ (16), ‘GFC_STD_GNU’ (32), ‘GFC_STD_LEGACY’ (64), ‘GFC_STD_F2008’ (128), ‘GFC_STD_F2008_OBS’ (256), ‘GFC_STD_F2018’ (512), ‘GFC_STD_F2018_OBS’ (1024), ‘GFC_STD_F2018_DEL’ (2048), ‘GFC_STD_F2023’ (4096), and ‘GFC_STD_F2023_DEL’ (8192). Default: ‘GFC_STD_F95_OBS | GFC_STD_F95_DEL | GFC_STD_F95 | GFC_STD_F2003 | GFC_STD_F2008 | GFC_STD_F2008_OBS | GFC_STD_F77 | GFC_STD_F2018 | GFC_STD_F2018_OBS | GFC_STD_F2018_DEL | GFC_STD_F2023 | GFC_STD_F2023_DEL | GFC_STD_GNU | GFC_STD_LEGACY’. OPTION[1] Standard-warning flag; prints a warning to standard error. Default: ‘GFC_STD_F95_DEL | GFC_STD_LEGACY’. OPTION[2] If non zero, enable pedantic checking. Default: off. OPTION[3] Unused. OPTION[4] If non zero, enable backtracing on run-time errors. Default: off. (Default in the compiler: on.) Note: Installs a signal handler and requires command-line initialization using ‘_gfortran_set_args’. OPTION[5] If non zero, supports signed zeros. Default: enabled. OPTION[6] Enables run-time checking. Possible values are (bitwise or-ed): GFC_RTCHECK_BOUNDS (1), GFC_RTCHECK_ARRAY_TEMPS (2), GFC_RTCHECK_RECURSION (4), GFC_RTCHECK_DO (8), GFC_RTCHECK_POINTER (16), GFC_RTCHECK_MEM (32), GFC_RTCHECK_BITS (64). Default: disabled. OPTION[7] Unused. OPTION[8] Show a warning when invoking ‘STOP’ and ‘ERROR STOP’ if a floating-point exception occurred. Possible values are (bitwise or-ed) ‘GFC_FPE_INVALID’ (1), ‘GFC_FPE_DENORMAL’ (2), ‘GFC_FPE_ZERO’ (4), ‘GFC_FPE_OVERFLOW’ (8), ‘GFC_FPE_UNDERFLOW’ (16), ‘GFC_FPE_INEXACT’ (32). Default: None (0). (Default in the compiler: ‘GFC_FPE_INVALID | GFC_FPE_DENORMAL | GFC_FPE_ZERO | GFC_FPE_OVERFLOW | GFC_FPE_UNDERFLOW’.) _Example_: /* Use gfortran 4.9 default options. */ static int options[] = {68, 511, 0, 0, 1, 1, 0, 0, 31}; _gfortran_set_options (9, &options);  File: gfortran.info, Node: _gfortran_set_convert, Next: _gfortran_set_record_marker, Prev: _gfortran_set_options, Up: Non-Fortran Main Program 6.3.3 ‘_gfortran_set_convert’ -- Set endian conversion ------------------------------------------------------ _Synopsis_: ‘void _gfortran_set_convert (int conv)’ _Description_: ‘_gfortran_set_convert’ set the representation of data for unformatted files. _Arguments_: CONV Endian conversion, possible values: GFC_CONVERT_NATIVE (0, default), GFC_CONVERT_SWAP (1), GFC_CONVERT_BIG (2), GFC_CONVERT_LITTLE (3). _Example_: int main (int argc, char *argv[]) { /* Initialize libgfortran. */ _gfortran_set_args (argc, argv); _gfortran_set_convert (1); return 0; }  File: gfortran.info, Node: _gfortran_set_record_marker, Next: _gfortran_set_fpe, Prev: _gfortran_set_convert, Up: Non-Fortran Main Program 6.3.4 ‘_gfortran_set_record_marker’ -- Set length of record markers ------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_set_record_marker (int val)’ _Description_: ‘_gfortran_set_record_marker’ sets the length of record markers for unformatted files. _Arguments_: VAL Length of the record marker; valid values are 4 and 8. Default is 4. _Example_: int main (int argc, char *argv[]) { /* Initialize libgfortran. */ _gfortran_set_args (argc, argv); _gfortran_set_record_marker (8); return 0; }  File: gfortran.info, Node: _gfortran_set_fpe, Next: _gfortran_set_max_subrecord_length, Prev: _gfortran_set_record_marker, Up: Non-Fortran Main Program 6.3.5 ‘_gfortran_set_fpe’ -- Enable floating point exception traps ------------------------------------------------------------------ _Synopsis_: ‘void _gfortran_set_fpe (int val)’ _Description_: ‘_gfortran_set_fpe’ enables floating point exception traps for the specified exceptions. On most systems, this results in a ‘SIGFPE’ signal being sent and the program being aborted. _Arguments_: OPTION[0] IEEE exceptions. Possible values are (bitwise or-ed) zero (0, default) no trapping, ‘GFC_FPE_INVALID’ (1), ‘GFC_FPE_DENORMAL’ (2), ‘GFC_FPE_ZERO’ (4), ‘GFC_FPE_OVERFLOW’ (8), ‘GFC_FPE_UNDERFLOW’ (16), and ‘GFC_FPE_INEXACT’ (32). _Example_: int main (int argc, char *argv[]) { /* Initialize libgfortran. */ _gfortran_set_args (argc, argv); /* FPE for invalid operations such as SQRT(-1.0). */ _gfortran_set_fpe (1); return 0; }  File: gfortran.info, Node: _gfortran_set_max_subrecord_length, Prev: _gfortran_set_fpe, Up: Non-Fortran Main Program 6.3.6 ‘_gfortran_set_max_subrecord_length’ -- Set subrecord length ------------------------------------------------------------------ _Synopsis_: ‘void _gfortran_set_max_subrecord_length (int val)’ _Description_: ‘_gfortran_set_max_subrecord_length’ set the maximum length for a subrecord. This option only makes sense for testing and debugging of unformatted I/O. _Arguments_: VAL the maximum length for a subrecord; the maximum permitted value is 2147483639, which is also the default. _Example_: int main (int argc, char *argv[]) { /* Initialize libgfortran. */ _gfortran_set_args (argc, argv); _gfortran_set_max_subrecord_length (8); return 0; }  File: gfortran.info, Node: Naming and argument-passing conventions, Prev: Non-Fortran Main Program, Up: Mixed-Language Programming 6.4 Naming and argument-passing conventions =========================================== This section gives an overview about the naming convention of procedures and global variables and about the argument passing conventions used by GNU Fortran. If a C binding has been specified, the naming convention and some of the argument-passing conventions change. If possible, mixed-language and mixed-compiler projects should use the better defined C binding for interoperability. See *note Interoperability with C::. * Menu: * Naming conventions:: * Argument passing conventions::  File: gfortran.info, Node: Naming conventions, Next: Argument passing conventions, Up: Naming and argument-passing conventions 6.4.1 Naming conventions ------------------------ According the Fortran standard, valid Fortran names consist of a letter between ‘A’ to ‘Z’, ‘a’ to ‘z’, digits ‘0’, ‘1’ to ‘9’ and underscores (‘_’) with the restriction that names may only start with a letter. As vendor extension, the dollar sign (‘$’) is additionally permitted with the option ‘-fdollar-ok’, but not as first character and only if the target system supports it. By default, the procedure name is the lowercased Fortran name with an appended underscore (‘_’); using ‘-fno-underscoring’ no underscore is appended while ‘-fsecond-underscore’ appends two underscores. Depending on the target system and the calling convention, the procedure might be additionally dressed; for instance, on 32bit Windows with ‘stdcall’, an at-sign ‘@’ followed by an integer number is appended. For the changing the calling convention, see *note GNU Fortran Compiler Directives::. For common blocks, the same convention is used, i.e. by default an underscore is appended to the lowercased Fortran name. Blank commons have the name ‘__BLNK__’. For procedures and variables declared in the specification space of a module, the name is formed by ‘__’, followed by the lowercased module name, ‘_MOD_’, and the lowercased Fortran name. Note that no underscore is appended.  File: gfortran.info, Node: Argument passing conventions, Prev: Naming conventions, Up: Naming and argument-passing conventions 6.4.2 Argument passing conventions ---------------------------------- Subroutines do not return a value (matching C99's ‘void’) while functions either return a value as specified in the platform ABI or the result variable is passed as hidden argument to the function and no result is returned. A hidden result variable is used when the result variable is an array or of type ‘CHARACTER’. Arguments are passed according to the platform ABI. In particular, complex arguments might not be compatible to a struct with two real components for the real and imaginary part. The argument passing matches the one of C99's ‘_Complex’. Functions with scalar complex result variables return their value and do not use a by-reference argument. Note that with the ‘-ff2c’ option, the argument passing is modified and no longer completely matches the platform ABI. Some other Fortran compilers use ‘f2c’ semantic by default; this might cause problems with interoperability. GNU Fortran passes most arguments by reference, i.e. by passing a pointer to the data. Note that the compiler might use a temporary variable into which the actual argument has been copied, if required semantically (copy-in/copy-out). For arguments with ‘ALLOCATABLE’ and ‘POINTER’ attribute (including procedure pointers), a pointer to the pointer is passed such that the pointer address can be modified in the procedure. For dummy arguments with the ‘VALUE’ attribute: Scalar arguments of the type ‘INTEGER’, ‘LOGICAL’, ‘REAL’ and ‘COMPLEX’ are passed by value according to the platform ABI. (As vendor extension and not recommended, using ‘%VAL()’ in the call to a procedure has the same effect.) For ‘TYPE(C_PTR)’ and procedure pointers, the pointer itself is passed such that it can be modified without affecting the caller. For Boolean (‘LOGICAL’) arguments, please note that GCC expects only the integer value 0 and 1. If a GNU Fortran ‘LOGICAL’ variable contains another integer value, the result is undefined. As some other Fortran compilers use -1 for ‘.TRUE.’, extra care has to be taken - such as passing the value as ‘INTEGER’. (The same value restriction also applies to other front ends of GCC, e.g. to GCC's C99 compiler for ‘_Bool’ or GCC's Ada compiler for ‘Boolean’.) For arguments of ‘CHARACTER’ type, the character length is passed as a hidden argument at the end of the argument list, except when the corresponding dummy argument is declared as ‘TYPE(*)’. For deferred-length strings, the value is passed by reference, otherwise by value. The character length has the C type ‘size_t’ (or ‘INTEGER(kind=C_SIZE_T)’ in Fortran). Note that this is different to older versions of the GNU Fortran compiler, where the type of the hidden character length argument was a C ‘int’. In order to retain compatibility with older versions, one can e.g. for the following Fortran procedure subroutine fstrlen (s, a) character(len=*) :: s integer :: a print*, len(s) end subroutine fstrlen define the corresponding C prototype as follows: #if __GNUC__ > 7 typedef size_t fortran_charlen_t; #else typedef int fortran_charlen_t; #endif void fstrlen_ (char*, int*, fortran_charlen_t); In order to avoid such compiler-specific details, for new code it is instead recommended to use the ISO_C_BINDING feature. Note with C binding, ‘CHARACTER(len=1)’ result variables are returned according to the platform ABI and no hidden length argument is used for dummy arguments; with ‘VALUE’, those variables are passed by value. For ‘OPTIONAL’ dummy arguments, an absent argument is denoted by a NULL pointer, except for scalar dummy arguments of intrinsic type or derived type (but not ‘CLASS’) and that have the ‘VALUE’ attribute. For those, a hidden Boolean argument (‘logical(kind=C_bool),value’) is used to indicate whether the argument is present. Arguments that are assumed-shape, assumed-rank or deferred-rank arrays or, with ‘-fcoarray=lib’, allocatable scalar coarrays use an array descriptor. All other arrays pass the address of the first element of the array. With ‘-fcoarray=lib’, the token and the offset belonging to nonallocatable coarrays dummy arguments are passed as hidden argument along the character length hidden arguments. The token is an opaque pointer identifying the coarray and the offset is a passed-by-value integer of kind ‘C_PTRDIFF_T’, denoting the byte offset between the base address of the coarray and the passed scalar or first element of the passed array. The arguments are passed in the following order • Result variable, when the function result is passed by reference • Character length of the function result, if it is a of type ‘CHARACTER’ and no C binding is used • The arguments in the order in which they appear in the Fortran declaration • The present status for optional arguments with value attribute, which are internally passed by value • The character length and/or coarray token and offset for the first argument which is a ‘CHARACTER’ or a nonallocatable coarray dummy argument, followed by the hidden arguments of the next dummy argument of such a type  File: gfortran.info, Node: Coarray Programming, Next: Intrinsic Procedures, Prev: Mixed-Language Programming, Up: Top 7 Coarray Programming ********************* * Menu: * Type and enum ABI Documentation:: * Function ABI Documentation::  File: gfortran.info, Node: Type and enum ABI Documentation, Next: Function ABI Documentation, Up: Coarray Programming 7.1 Type and enum ABI Documentation =================================== * Menu: * caf_token_t:: * caf_register_t:: * caf_deregister_t:: * caf_reference_t:: * caf_team_t::  File: gfortran.info, Node: caf_token_t, Next: caf_register_t, Up: Type and enum ABI Documentation 7.1.1 ‘caf_token_t’ ------------------- Typedef of type ‘void *’ on the compiler side. Can be any data type on the library side.  File: gfortran.info, Node: caf_register_t, Next: caf_deregister_t, Prev: caf_token_t, Up: Type and enum ABI Documentation 7.1.2 ‘caf_register_t’ ---------------------- Indicates which kind of coarray variable should be registered. typedef enum caf_register_t { CAF_REGTYPE_COARRAY_STATIC, CAF_REGTYPE_COARRAY_ALLOC, CAF_REGTYPE_LOCK_STATIC, CAF_REGTYPE_LOCK_ALLOC, CAF_REGTYPE_CRITICAL, CAF_REGTYPE_EVENT_STATIC, CAF_REGTYPE_EVENT_ALLOC, CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY, CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY } caf_register_t; The values ‘CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY’ and ‘CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY’ are for allocatable components in derived type coarrays only. The first one sets up the token without allocating memory for allocatable component. The latter one only allocates the memory for an allocatable component in a derived type coarray. The token needs to be set up previously by the REGISTER_ONLY. This allows having allocatable components unallocated on some images. The status of whether an allocatable component is allocated on a remote image can be queried by ‘_caf_is_present’ which used internally by the ‘ALLOCATED’ intrinsic.  File: gfortran.info, Node: caf_deregister_t, Next: caf_reference_t, Prev: caf_register_t, Up: Type and enum ABI Documentation 7.1.3 ‘caf_deregister_t’ ------------------------ typedef enum caf_deregister_t { CAF_DEREGTYPE_COARRAY_DEREGISTER, CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY } caf_deregister_t; Allows to specify the type of deregistration of a coarray object. The ‘CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY’ flag is only allowed for allocatable components in derived type coarrays.  File: gfortran.info, Node: caf_reference_t, Next: caf_team_t, Prev: caf_deregister_t, Up: Type and enum ABI Documentation 7.1.4 ‘caf_reference_t’ ----------------------- The structure used for implementing arbitrary reference chains. A ‘CAF_REFERENCE_T’ allows to specify a component reference or any kind of array reference of any rank supported by gfortran. For array references all kinds as known by the compiler/Fortran standard are supported indicated by a ‘MODE’. typedef enum caf_ref_type_t { /* Reference a component of a derived type, either regular one or an allocatable or pointer type. For regular ones idx in caf_reference_t is set to -1. */ CAF_REF_COMPONENT, /* Reference an allocatable array. */ CAF_REF_ARRAY, /* Reference a non-allocatable/non-pointer array. I.e., the coarray object has no array descriptor associated and the addressing is done completely using the ref. */ CAF_REF_STATIC_ARRAY } caf_ref_type_t; typedef enum caf_array_ref_t { /* No array ref. This terminates the array ref. */ CAF_ARR_REF_NONE = 0, /* Reference array elements given by a vector. Only for this mode caf_reference_t.u.a.dim[i].v is valid. */ CAF_ARR_REF_VECTOR, /* A full array ref (:). */ CAF_ARR_REF_FULL, /* Reference a range on elements given by start, end and stride. */ CAF_ARR_REF_RANGE, /* Only a single item is referenced given in the start member. */ CAF_ARR_REF_SINGLE, /* An array ref of the kind (i:), where i is an arbitrary valid index in the array. The index i is given in the start member. */ CAF_ARR_REF_OPEN_END, /* An array ref of the kind (:i), where the lower bound of the array ref is given by the remote side. The index i is given in the end member. */ CAF_ARR_REF_OPEN_START } caf_array_ref_t; /* References to remote components of a derived type. */ typedef struct caf_reference_t { /* A pointer to the next ref or NULL. */ struct caf_reference_t *next; /* The type of the reference. */ /* caf_ref_type_t, replaced by int to allow specification in fortran FE. */ int type; /* The size of an item referenced in bytes. I.e. in an array ref this is the factor to advance the array pointer with to get to the next item. For component refs this gives just the size of the element referenced. */ size_t item_size; union { struct { /* The offset (in bytes) of the component in the derived type. Unused for allocatable or pointer components. */ ptrdiff_t offset; /* The offset (in bytes) to the caf_token associated with this component. NULL, when not allocatable/pointer ref. */ ptrdiff_t caf_token_offset; } c; struct { /* The mode of the array ref. See CAF_ARR_REF_*. */ /* caf_array_ref_t, replaced by unsigend char to allow specification in fortran FE. */ unsigned char mode[GFC_MAX_DIMENSIONS]; /* The type of a static array. Unset for array's with descriptors. */ int static_array_type; /* Subscript refs (s) or vector refs (v). */ union { struct { /* The start and end boundary of the ref and the stride. */ index_type start, end, stride; } s; struct { /* nvec entries of kind giving the elements to reference. */ void *vector; /* The number of entries in vector. */ size_t nvec; /* The integer kind used for the elements in vector. */ int kind; } v; } dim[GFC_MAX_DIMENSIONS]; } a; } u; } caf_reference_t; The references make up a single linked list of reference operations. The ‘NEXT’ member links to the next reference or NULL to indicate the end of the chain. Component and array refs can be arbitrarily mixed as long as they comply to the Fortran standard. _Notes_: The member ‘STATIC_ARRAY_TYPE’ is used only when the ‘TYPE’ is ‘CAF_REF_STATIC_ARRAY’. The member gives the type of the data referenced. Because no array descriptor is available for a descriptorless array and type conversion still needs to take place the type is transported here. At the moment ‘CAF_ARR_REF_VECTOR’ is not implemented in the front end for descriptorless arrays. The library caf_single has untested support for it.  File: gfortran.info, Node: caf_team_t, Prev: caf_reference_t, Up: Type and enum ABI Documentation 7.1.5 ‘caf_team_t’ ------------------ Opaque pointer to represent a team-handle. This type is a stand-in for the future implementation of teams. It is about to change without further notice.  File: gfortran.info, Node: Function ABI Documentation, Prev: Type and enum ABI Documentation, Up: Coarray Programming 7.2 Function ABI Documentation ============================== * Menu: * _gfortran_caf_init:: Initialization function * _gfortran_caf_finish:: Finalization function * _gfortran_caf_this_image:: Querying the image number * _gfortran_caf_num_images:: Querying the maximal number of images * _gfortran_caf_image_status :: Query the status of an image * _gfortran_caf_failed_images :: Get an array of the indexes of the failed images * _gfortran_caf_stopped_images :: Get an array of the indexes of the stopped images * _gfortran_caf_register:: Registering coarrays * _gfortran_caf_deregister:: Deregistering coarrays * _gfortran_caf_register_accessor:: Register an accessor for remote access * _gfortran_caf_register_accessors_finish:: Finish registering accessor functions * _gfortran_caf_get_remote_function_index:: Get the index of an accessor * _gfortran_caf_get_from_remote:: Getting data from a remote image using a remote side accessor * _gfortran_caf_is_present_on_remote:: Check that a coarray or a part of it is allocated on the remote image * _gfortran_caf_send_to_remote:: Send data to a remote image using a remote side accessor to store it * _gfortran_caf_transfer_between_remotes:: Initiate data transfer between to remote images * _gfortran_caf_sendget_by_ref:: Sending data between remote images using enhanced references * _gfortran_caf_lock:: Locking a lock variable * _gfortran_caf_unlock:: Unlocking a lock variable * _gfortran_caf_event_post:: Post an event * _gfortran_caf_event_wait:: Wait that an event occurred * _gfortran_caf_event_query:: Query event count * _gfortran_caf_sync_all:: All-image barrier * _gfortran_caf_sync_images:: Barrier for selected images * _gfortran_caf_sync_memory:: Wait for completion of segment-memory operations * _gfortran_caf_error_stop:: Error termination with exit code * _gfortran_caf_error_stop_str:: Error termination with string * _gfortran_caf_fail_image :: Mark the image failed and end its execution * _gfortran_caf_atomic_define:: Atomic variable assignment * _gfortran_caf_atomic_ref:: Atomic variable reference * _gfortran_caf_atomic_cas:: Atomic compare and swap * _gfortran_caf_atomic_op:: Atomic operation * _gfortran_caf_co_broadcast:: Sending data to all images * _gfortran_caf_co_max:: Collective maximum reduction * _gfortran_caf_co_min:: Collective minimum reduction * _gfortran_caf_co_sum:: Collective summing reduction * _gfortran_caf_co_reduce:: Generic collective reduction  File: gfortran.info, Node: _gfortran_caf_init, Next: _gfortran_caf_finish, Up: Function ABI Documentation 7.2.1 ‘_gfortran_caf_init’ -- Initialization function ----------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_init (int *argc, char ***argv)’ _Description_: This function is called at startup of the program before the Fortran main program, if the latter has been compiled with ‘-fcoarray=lib’. It takes as arguments the command-line arguments of the program. It is permitted to pass two ‘NULL’ pointers as argument; if non-‘NULL’, the library is permitted to modify the arguments. _Arguments_: ARGC intent(inout) An integer pointer with the number of arguments passed to the program or ‘NULL’. ARGV intent(inout) A pointer to an array of strings with the command-line arguments or ‘NULL’. _Notes_: The function is modelled after the initialization function of the Message Passing Interface (MPI) specification. Due to the way coarray registration works, it might not be the first call to the library. If the main program is not written in Fortran and only a library uses coarrays, it can happen that this function is never called. Therefore, it is recommended that the library does not rely on the passed arguments and whether the call has been done.  File: gfortran.info, Node: _gfortran_caf_finish, Next: _gfortran_caf_this_image, Prev: _gfortran_caf_init, Up: Function ABI Documentation 7.2.2 ‘_gfortran_caf_finish’ -- Finalization function ----------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_finish (void)’ _Description_: This function is called at the end of the Fortran main program, if it has been compiled with the ‘-fcoarray=lib’ option. _Notes_: For non-Fortran programs, it is recommended to call the function at the end of the main program. To ensure that the shutdown is also performed for programs where this function is not explicitly invoked, for instance non-Fortran programs or calls to the system's exit() function, the library can use a destructor function. Note that programs can also be terminated using the STOP and ERROR STOP statements; those use different library calls.  File: gfortran.info, Node: _gfortran_caf_this_image, Next: _gfortran_caf_num_images, Prev: _gfortran_caf_finish, Up: Function ABI Documentation 7.2.3 ‘_gfortran_caf_this_image’ -- Querying the image number ------------------------------------------------------------- _Synopsis_: ‘int _gfortran_caf_this_image (int distance)’ _Description_: This function returns the current image number, which is a positive number. _Arguments_: DISTANCE As specified for the ‘this_image’ intrinsic in TS18508. Shall be a nonnegative number. _Notes_: If the Fortran intrinsic ‘this_image’ is invoked without an argument, which is the only permitted form in Fortran 2008, GCC passes ‘0’ as first argument.  File: gfortran.info, Node: _gfortran_caf_num_images, Next: _gfortran_caf_image_status, Prev: _gfortran_caf_this_image, Up: Function ABI Documentation 7.2.4 ‘_gfortran_caf_num_images’ -- Querying the maximal number of images ------------------------------------------------------------------------- _Synopsis_: ‘int _gfortran_caf_num_images(int distance, int failed)’ _Description_: This function returns the number of images in the current team, if DISTANCE is 0 or the number of images in the parent team at the specified distance. If FAILED is -1, the function returns the number of all images at the specified distance; if it is 0, the function returns the number of nonfailed images, and if it is 1, it returns the number of failed images. _Arguments_: DISTANCE the distance from this image to the ancestor. Shall be positive. FAILED shall be -1, 0, or 1 _Notes_: This function follows TS18508. If the num_image intrinsic has no arguments, then the compiler passes ‘distance=0’ and ‘failed=-1’ to the function.  File: gfortran.info, Node: _gfortran_caf_image_status, Next: _gfortran_caf_failed_images, Prev: _gfortran_caf_num_images, Up: Function ABI Documentation 7.2.5 ‘_gfortran_caf_image_status’ -- Query the status of an image ------------------------------------------------------------------ _Synopsis_: ‘int _gfortran_caf_image_status (int image, caf_team_t * team)’ _Description_: Get the status of the image given by the id IMAGE of the team given by TEAM. Valid results are zero, for image is ok, ‘STAT_STOPPED_IMAGE’ from the ISO_FORTRAN_ENV module to indicate that the image has been stopped and ‘STAT_FAILED_IMAGE’ also from ISO_FORTRAN_ENV to indicate that the image has executed a ‘FAIL IMAGE’ statement. _Arguments_: IMAGE the positive scalar id of the image in the current TEAM. TEAM optional; team on the which the inquiry is to be performed. _Notes_: This function follows TS18508. Because team-functionality is not yet implemented a null pointer is passed for the TEAM argument at the moment.  File: gfortran.info, Node: _gfortran_caf_failed_images, Next: _gfortran_caf_stopped_images, Prev: _gfortran_caf_image_status, Up: Function ABI Documentation 7.2.6 ‘_gfortran_caf_failed_images’ -- Get an array of the indexes of the failed images --------------------------------------------------------------------------------------- _Synopsis_: ‘int _gfortran_caf_failed_images (caf_team_t * team, int * kind)’ _Description_: Get an array of image indexes in the current TEAM that have failed. The array is sorted ascendingly. When TEAM is not provided the current team is to be used. When KIND is provided then the resulting array is of that integer kind else it is of default integer kind. The returns an unallocated size zero array when no images have failed. _Arguments_: TEAM optional; team on the which the inquiry is to be performed. IMAGE optional; the kind of the resulting integer array. _Notes_: This function follows TS18508. Because team-functionality is not yet implemented a null pointer is passed for the TEAM argument at the moment.  File: gfortran.info, Node: _gfortran_caf_stopped_images, Next: _gfortran_caf_register, Prev: _gfortran_caf_failed_images, Up: Function ABI Documentation 7.2.7 ‘_gfortran_caf_stopped_images’ -- Get an array of the indexes of the stopped images ----------------------------------------------------------------------------------------- _Synopsis_: ‘int _gfortran_caf_stopped_images (caf_team_t * team, int * kind)’ _Description_: Get an array of image indexes in the current TEAM that have stopped. The array is sorted ascendingly. When TEAM is not provided the current team is to be used. When KIND is provided then the resulting array is of that integer kind else it is of default integer kind. The returns an unallocated size zero array when no images have failed. _Arguments_: TEAM optional; team on the which the inquiry is to be performed. IMAGE optional; the kind of the resulting integer array. _Notes_: This function follows TS18508. Because team-functionality is not yet implemented a null pointer is passed for the TEAM argument at the moment.  File: gfortran.info, Node: _gfortran_caf_register, Next: _gfortran_caf_deregister, Prev: _gfortran_caf_stopped_images, Up: Function ABI Documentation 7.2.8 ‘_gfortran_caf_register’ -- Registering coarrays ------------------------------------------------------ _Synopsis_: ‘void _gfortran_caf_register (size_t size, caf_register_t type, caf_token_t *token, gfc_descriptor_t *desc, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Registers memory for a coarray and creates a token to identify the coarray. The routine is called for both coarrays with ‘SAVE’ attribute and using an explicit ‘ALLOCATE’ statement. If an error occurs and STAT is a ‘NULL’ pointer, the function shall abort with printing an error message and starting the error termination. If no error occurs and STAT is present, it shall be set to zero. Otherwise, it shall be set to a positive value and, if not-‘NULL’, ERRMSG shall be set to a string describing the failure. The routine shall register the memory provided in the ‘DATA’-component of the array descriptor DESC, when that component is non-‘NULL’, else it shall allocate sufficient memory and provide a pointer to it in the ‘DATA’-component of DESC. The array descriptor has rank zero, when a scalar object is to be registered and the array descriptor may be invalid after the call to ‘_gfortran_caf_register’. When an array is to be allocated the descriptor persists. For ‘CAF_REGTYPE_COARRAY_STATIC’ and ‘CAF_REGTYPE_COARRAY_ALLOC’, the passed size is the byte size requested. For ‘CAF_REGTYPE_LOCK_STATIC’, ‘CAF_REGTYPE_LOCK_ALLOC’ and ‘CAF_REGTYPE_CRITICAL’ it is the array size or one for a scalar. When ‘CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY’ is used, then only a token for an allocatable or pointer component is created. The ‘SIZE’ parameter is not used then. On the contrary when ‘CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY’ is specified, then the TOKEN needs to be registered by a previous call with regtype ‘CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY’ and either the memory specified in the DESC's data-ptr is registered or allocate when the data-ptr is ‘NULL’. _Arguments_: SIZE For normal coarrays, the byte size of the coarray to be allocated; for lock types and event types, the number of elements. TYPE one of the caf_register_t types. TOKEN intent(out) An opaque pointer identifying the coarray. DESC intent(inout) The (pseudo) array descriptor. STAT intent(out) For allocatable coarrays, stores the STAT=; may be ‘NULL’ ERRMSG intent(out) When an error occurs, this is set to an error message; may be ‘NULL’ ERRMSG_LEN the buffer size of errmsg. _Notes_: Nonallocatable coarrays have to be registered prior use from remote images. In order to guarantee this, they have to be registered before the main program. This can be achieved by creating constructor functions. That is what GCC does such that also for nonallocatable coarrays the memory is allocated and no static memory is used. The token permits to identify the coarray; to the processor, the token is a nonaliasing pointer. The library can, for instance, store the base address of the coarray in the token, some handle or a more complicated struct. The library may also store the array descriptor DESC when its rank is nonzero. For lock types, the value shall only be used for checking the allocation status. Note that for critical blocks, the locking is only required on one image; in the locking statement, the processor shall always pass an image index of one for critical-block lock variables (‘CAF_REGTYPE_CRITICAL’). For lock types and critical-block variables, the initial value shall be unlocked (or, respectively, not in critical section) such as the value false; for event types, the initial state should be no event, e.g. zero.  File: gfortran.info, Node: _gfortran_caf_deregister, Next: _gfortran_caf_register_accessor, Prev: _gfortran_caf_register, Up: Function ABI Documentation 7.2.9 ‘_gfortran_caf_deregister’ -- Deregistering coarrays ---------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_deregister (caf_token_t *token, caf_deregister_t type, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Called to free or deregister the memory of a coarray; the processor calls this function for automatic and explicit deallocation. In case of an error, this function shall fail with an error message, unless the STAT variable is not null. The library is only expected to free memory it allocated itself during a call to ‘_gfortran_caf_register’. _Arguments_: TOKEN the token to free. TYPE the type of action to take for the coarray. A ‘CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY’ is allowed only for allocatable or pointer components of derived type coarrays. The action only deallocates the local memory without deleting the token. STAT intent(out) Stores the STAT=; may be NULL ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL ERRMSG_LEN the buffer size of errmsg. _Notes_: For nonallocatable coarrays this function is never called. If a cleanup is required, it has to be handled via the finish, stop and error stop functions, and via destructors.  File: gfortran.info, Node: _gfortran_caf_register_accessor, Next: _gfortran_caf_register_accessors_finish, Prev: _gfortran_caf_deregister, Up: Function ABI Documentation 7.2.10 ‘_gfortran_caf_register_accessor’ -- Register an accessor for remote access ---------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_register_accessor (const int hash, void (*accessor)(void **, int32_t *, void *, void *, size_t *, size_t *))’ _Description_: Identification of access funtions across images is done using a unique hash. For each given hash an accessor has to be registered. This routine is expected to register an accessor function pointer for the given hash in nearly constant time. I.e. it is expected to add the hash and accessor to a buffer and return. Sorting shall be done in ‘_gfortran_caf_register_accessors_finish’. _Arguments_: HASH intent(in) The unique hash value this accessor is to be identified by. ACCESSOR intent(in) A pointer to the function on this image. The function has the signature ‘void accessor (void **dst_ptr, int32_t *free_dst, void *src_ptr, void *get_data, size_t *opt_src_charlen, size_t *opt_dst_charlen)’. GFortran ensures that functions provided to ‘_gfortran_caf_register_accessor’ adhere to this interface. _Notes_: This function is required to have a nearly constant runtime complexity, because it will be called to register multiple accessor in a sequence. GFortran ensures that before the first remote accesses commences ‘_gfortran_caf_register_accessors_finish’ is called at least once. It is valid to register further accessors after a call to ‘_gfortran_caf_register_accessors_finish’. It is invalid to call ‘_gfortran_caf_register_accessor’ after the first remote access has been done. See also *note _gfortran_caf_register_accessors_finish:: and *note _gfortran_caf_get_remote_function_index::  File: gfortran.info, Node: _gfortran_caf_register_accessors_finish, Next: _gfortran_caf_get_remote_function_index, Prev: _gfortran_caf_register_accessor, Up: Function ABI Documentation 7.2.11 ‘_gfortran_caf_register_accessors_finish’ -- Finish registering accessor functions ----------------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_register_accessors_finish ()’ _Description_: Called to finalize registering of accessor functions. This function is expected to prepare a lookup table that has fast lookup time for the hash supplied to ‘_gfortran_caf_get_remote_function_index’ and constant access time for indexing operations. _Arguments_: No arguments. _Notes_: This function may be called multiple times with and without new hash-accessors- pairs being added. The post-condition after each call has to be that hashes can be looked up quickly and indexing on the lookup table of hash-accessor-pairs is a constant time operation.  File: gfortran.info, Node: _gfortran_caf_get_remote_function_index, Next: _gfortran_caf_get_from_remote, Prev: _gfortran_caf_register_accessors_finish, Up: Function ABI Documentation 7.2.12 ‘_gfortran_caf_get_remote_function_index’ -- Get the index of an accessor -------------------------------------------------------------------------------- _Synopsis_: ‘int _gfortran_caf_get_remote_function_index (const int hash)’ _Description_: Return the index of the accessor in the lookup table build by *note _gfortran_caf_register_accessor:: and *note _gfortran_caf_register_accessors_finish::. This function is expected to be fast, because it may be called often. A log(N) lookup time for a given hash is preferred. The reference implementation uses ‘bsearch ()’, for example. The index returned shall be an array index to be used by *note _gfortran_caf_get_from_remote::, i.e. a constant time operation is mandatory for quick access. The GFortran compiler ensures that ‘_gfortran_caf_get_remote_function_index’ is called once only for each hash and the result be stored in a static variable to prevent future redundant lookups. _Arguments_: HASH intent(in) The hash of the accessor desired. _Result_: The zero based index to access the accessor funtion in a lookup table. On error, ‘-1’ can be returned. _Notes_: The function's complexity is expected to be significantly smaller than N, where N is the number of all accessors registered. Although returning ‘-1’ is valid, will this most likely crash the Fortran program when accessing the -1-th accessor function. It is therefore advised to terminate with an error message, when the hash could not be found.  File: gfortran.info, Node: _gfortran_caf_get_from_remote, Next: _gfortran_caf_is_present_on_remote, Prev: _gfortran_caf_get_remote_function_index, Up: Function ABI Documentation 7.2.13 ‘_gfortran_caf_get_from_remote’ -- Getting data from a remote image using a remote side accessor ------------------------------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_get_from_remote (caf_token_t token, const gfc_descriptor_t *opt_src_desc, const size_t *opt_src_charlen, const int image_index, const size_t dst_size, void **dst_data, size_t *opt_dst_charlen, gfc_descriptor_t *opt_dst_desc, const bool may_realloc_dst, const int getter_index, void *get_data, const size_t get_data_size, int *stat, caf_team_t *team, int *team_number)’ _Description_: Called to get a scalar, an array section or a whole array from a remote image identified by the IMAGE_INDEX. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. OPT_SRC_DESCintent(in) A pointer to the descriptor when the object identified by TOKEN is an array with a descriptor. The parameter needs to be set to ‘NULL’, when TOKEN identifies a scalar. OPT_SRC_CHARLENintent(in) When the object to get is a char array with deferred length, then this parameter needs to be set to point to its length. Else the parameter needs to be set to ‘NULL’. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number. ‘this_image ()’ is valid. DST_SIZE intent(in) The size of data expected to be transferred from the remote image. If the data type to get is a string or string array, then this needs to be set to the byte size of each character, i.e. ‘4’ for a ‘CHARACTER (KIND=4)’ string. The length of the string is then returned in ‘opt_dst_charlen’ (also for string arrays). DST_DATA intent(inout) A pointer to the adress the data is stored. To prevent copying of data into an output buffer the adress to the live data is returned here. When a descriptor is provided also its data-member is set to that adress. When MAY_REALLOC_DST is set, then the memory may be reallocated by the remote function, which needs to be replicated by this function. OPT_DST_CHARLENintent(inout) When a char array is returned, this parameter is set to the length where applicable. The value can also be read to prevent reallocation in the accessor. OPT_DST_DESCintent(inout) When a descriptor array is returned, it is stored in the memory pointed to by this optional parameter. When MAY_REALLOC_DST is set, then the descriptor may be changed, i.e. its bounds, but upto now not its rank. MAY_REALLOC_DSTintent(in) Set when the returned data may require reallocation of the output buffer in DST_DATA or OPT_DST_DESC. GETTER_INDEXintent(in) The index of the accessor to execute as returned by ‘_gfortran_caf_get_remote_function_index ()’. GET_DATA intent(inout) Additional data needed in the accessor. I.e., when an array reference uses a local variable V, it is transported in this structure and all references in the accessor are rewritten to access the member. The data in the structure of GET_DATA may be changed by the accessor, but these changes are lost to the calling Fortran program. GET_DATA_SIZEintent(in) The size of the GET_DATA structure. STAT intent(out) When non-‘NULL’ give the result of the operation, i.e., zero on success and non-zero on error. When ‘NULL’ and an error occurs, then an error message is printed and the program is terminated. TEAM intent(in) The opaque team handle as returned by ‘FORM TEAM’. Unused at the moment. TEAM_NUMBER intent(in) The number of the team this access is to be part of. Unused at the moment. _Notes_: It is permitted to have ‘image_index’ equal the current image; the memory to get and the memory to store the data may (partially) overlap. The implementation has to take care that it handles this case, e.g. using ‘memmove’ which handles (partially) overlapping memory.  File: gfortran.info, Node: _gfortran_caf_is_present_on_remote, Next: _gfortran_caf_send_to_remote, Prev: _gfortran_caf_get_from_remote, Up: Function ABI Documentation 7.2.14 ‘_gfortran_caf_is_present_on_remote’ -- Check that a coarray or a part of it is allocated on the remote image -------------------------------------------------------------------------------------------------------------------- _Synopsis_: ‘int32_t _gfortran_caf_is_present_on_remote (caf_token_t token, const int image_index, const int is_present_index, void *add_data, const size_t add_data_size)’ _Description_: Check if an allocatable coarray or a component of a derived type coarray is allocated on the remote image identified by the IMAGE_INDEX. The check is done by calling routine on the remote side. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number. ‘this_image ()’ is valid. IS_PRESENT_INDEXintent(in) The index of the accessor to execute as returned by ‘_gfortran_caf_get_remote_function_index ()’. ADD_DATA intent(inout) Additional data needed in the accessor. I.e., when an array reference uses a local variable V, it is transported in this structure and all references in the accessor are rewritten to access the member. The data in the structure of ADD_DATA may be changed by the accessor, but these changes are lost to the calling Fortran program. ADD_DATA_SIZEintent(in) The size of the ADD_DATA structure.  File: gfortran.info, Node: _gfortran_caf_send_to_remote, Next: _gfortran_caf_transfer_between_remotes, Prev: _gfortran_caf_is_present_on_remote, Up: Function ABI Documentation 7.2.15 ‘_gfortran_caf_send_to_remote’ -- Send data to a remote image using a remote side accessor to store it ------------------------------------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_send_to_remote (caf_token_t token, gfc_descriptor_t *opt_dst_desc, const size_t *opt_dst_charlen, const int image_index, const size_t src_size, const void *src_data, size_t *opt_src_charlen, const gfc_descriptor_t *opt_src_desc, const int setter_index, void *add_data, const size_t add_data_size, int *stat, caf_team_t *team, int *team_number)’ _Description_: Called to send a scalar, an array section or a whole array to a remote image identified by the IMAGE_INDEX. The call modifies the memory of the remote image. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. OPT_DST_DESCintent(inout) A pointer to the descriptor when the object identified by TOKEN is an array with a descriptor. The parameter needs to be set to ‘NULL’, when TOKEN identifies a scalar or is an array without a descriptor. OPT_DST_CHARLENintent(in) When the object to send is a char array with deferred length, then this parameter needs to be set to point to its length. Else the parameter needs to be set to ‘NULL’. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number. ‘this_image ()’ is valid. SRC_SIZE intent(in) The size of data expected to be transferred to the remote image. If the data type to get is a string or string array, then this needs to be set to the byte size of each character, i.e. ‘4’ for a ‘CHARACTER (KIND=4)’ string. The length of the string is then given in ‘opt_src_charlen’ (also for string arrays). SRC_DATA intent(in) A pointer the data to be send to the remote image. When a descriptor is provided in ‘opt_src_desc’ then this parameter can be ignored by the library implementing the coarray functionality. OPT_SRC_CHARLENintent(in) When a char array is send, this parameter is set to its length. OPT_SRC_DESCintent(in) When a descriptor array is send, then this parameter gives the handle. SETTER_INDEXintent(in) The index of the accessor to execute as returned by ‘_gfortran_caf_get_remote_function_index ()’. ADD_DATA intent(inout) Additional data needed in the accessor. I.e., when an array reference uses a local variable V, it is transported in this structure and all references in the accessor are rewritten to access the member. The data in the structure of ADD_DATA may be changed by the accessor, but these changes are lost to the calling Fortran program. ADD_DATA_SIZEintent(in) The size of the ADD_DATA structure. STAT intent(out) When non-‘NULL’ give the result of the operation, i.e., zero on success and non-zero on error. When ‘NULL’ and an error occurs, then an error message is printed and the program is terminated. TEAM intent(in) The opaque team handle as returned by ‘FORM TEAM’. Unused at the moment. TEAM_NUMBER intent(in) The number of the team this access is to be part of. Unused at the moment. _Notes_: It is permitted to have ‘image_index’ equal the current image; the memory to send the data to and the memory to read for the data may (partially) overlap. The implementation has to take care that it handles this case, e.g. using ‘memmove’ which handles (partially) overlapping memory.  File: gfortran.info, Node: _gfortran_caf_transfer_between_remotes, Next: _gfortran_caf_sendget_by_ref, Prev: _gfortran_caf_send_to_remote, Up: Function ABI Documentation 7.2.16 ‘_gfortran_caf_transfer_between_remotes’ -- Initiate data transfer between to remote images -------------------------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_transfer_between_remotes (caf_token_t dst_token, gfc_descriptor_t *opt_dst_desc, size_t *opt_dst_charlen, const int dst_image_index, const int dst_access_index, void *dst_add_data, const size_t dst_add_data_size, caf_token_t src_token, const gfc_descriptor_t *opt_src_desc, const size_t *opt_src_charlen, const int src_image_index, const int src_access_index, void *src_add_data, const size_t src_add_data_size, const size_t src_size, const bool scalar_transfer, int *dst_stat, int *src_stat, caf_team_t *dst_team, int *dst_team_number, caf_team_t *src_team, int *src_team_number) ’ _Description_: Initiates a transfer of data from one remote image to another remote image. The call modifies the memory of the receiving remote image given by ‘dst_image_index’. The ‘src_image_index’'s memory is not modified. The call returns when the transfer has commenced. _Arguments_: DST_TOKEN intent(in) An opaque pointer identifying the coarray on the receiving image. OPT_DST_DESCintent(inout) A pointer to the descriptor when the object identified by DST_TOKEN is an array with a descriptor. The parameter needs to be set to ‘NULL’, when DST_TOKEN identifies a scalar or is an array without a descriptor. OPT_DST_CHARLENintent(in) When the object to modify on the receiving image is a char array with deferred length, then this parameter needs to be set to point to its length. Else the parameter needs to be set to ‘NULL’. DST_IMAGE_INDEXintent(in) The ID of the receiving/destination remote image; must be a positive number. ‘this_image ()’ is valid. DST_ACCESS_INDEXintent(in) The index of the accessor to execute on the receiving image as returned by ‘_gfortran_caf_get_remote_function_index ()’. DST_ADD_DATAintent(inout) Additional data needed in the accessor on the receiving side. I.e., when an array reference uses a local variable V, it is transported in this structure and all references in the accessor are rewritten to access the member. The data in the structure of DST_ADD_DATA may be changed by the accessor, but these changes are lost to the calling Fortran program. DST_ADD_DATA_SIZEintent(in) The size of the DST_ADD_DATA structure. SRC_TOKEN intent(in) An opaque pointer identifying the coarray on the sending image. OPT_SRC_DESCintent(inout) A pointer to the descriptor when the object identified by SRC_TOKEN is an array with a descriptor. The parameter needs to be set to ‘NULL’, when SRC_TOKEN identifies a scalar or is an array without a descriptor. OPT_SRC_CHARLENintent(in) When the object to get from the source image is a char array with deferred length, then this parameter needs to be set to point to its length. Else the parameter needs to be set to ‘NULL’. SRC_IMAGE_INDEXintent(in) The ID of the sending/source remote image; must be a positive number. ‘this_image ()’ is valid. SRC_ACCESS_INDEXintent(in) The index of the accessor to execute on the sending image as returned by ‘_gfortran_caf_get_remote_function_index ()’. SRC_ADD_DATAintent(inout) Additional data needed in the accessor on the sending side. I.e., when an array reference uses a local variable V, it is transported in this structure and all references in the accessor are rewritten to access the member. The data in the structure of SRC_ADD_DATA may be changed by the accessor, but these changes are lost to the calling Fortran program. SRC_ADD_DATA_SIZEintent(in) The size of the SRC_ADD_DATA structure. SRC_SIZE intent(in) The size of data expected to be transferred between the images. If the data type to get is a string or string array, then this needs to be set to the byte size of each character, i.e. ‘4’ for a ‘CHARACTER (KIND=4)’ string. The length of the string is then given in ‘opt_src_charlen’ and ‘opt_dst_charlen’ (also for string arrays). SCALAR_TRANSFERintent(in) Is set to true when the data to be transfered between the two images is not an array with a descriptor. DST_STAT intent(out) When non-‘NULL’ give the result of the operation on the receiving side, i.e., zero on success and non-zero on error. When ‘NULL’ and an error occurs, then an error message is printed and the program is terminated. SRC_STAT intent(out) When non-‘NULL’ give the result of the operation on the sending side, i.e., zero on success and non-zero on error. When ‘NULL’ and an error occurs, then an error message is printed and the program is terminated. DST_TEAM intent(in) The opaque team handle as returned by ‘FORM TEAM’. Unused at the moment. DST_TEAM_NUMBERintent(in) The number of the team this access is to be part of. Unused at the moment. SRC_TEAM intent(in) The opaque team handle as returned by ‘FORM TEAM’. Unused at the moment. SRC_TEAM_NUMBERintent(in) The number of the team this access is to be part of. Unused at the moment. _Notes_: It is permitted to have both ‘dst_image_index’ and ‘src_image_index’ equal the current image; the memory to send the data to and the memory to read for the data may (partially) overlap. The implementation has to take care that it handles this case, e.g. using ‘memmove’ which handles (partially) overlapping memory.  File: gfortran.info, Node: _gfortran_caf_sendget_by_ref, Next: _gfortran_caf_lock, Prev: _gfortran_caf_transfer_between_remotes, Up: Function ABI Documentation 7.2.17 ‘_gfortran_caf_sendget_by_ref’ -- Sending data between remote images using enhanced references on both sides ------------------------------------------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_sendget_by_ref (caf_token_t dst_token, int dst_image_index, caf_reference_t *dst_refs, caf_token_t src_token, int src_image_index, caf_reference_t *src_refs, int dst_kind, int src_kind, bool may_require_tmp, int *dst_stat, int *src_stat, int dst_type, int src_type)’ _Description_: Called to send a scalar, an array section or a whole array from a remote image identified by the SRC_IMAGE_INDEX to a remote image identified by the DST_IMAGE_INDEX. _Arguments_: DST_TOKEN intent(in) An opaque pointer identifying the destination coarray. DST_IMAGE_INDEXintent(in) The ID of the destination remote image; must be a positive number. DST_REFS intent(in) The references on the remote array to store the data given by the source. Guaranteed to have at least one entry. SRC_TOKEN intent(in) An opaque pointer identifying the source coarray. SRC_IMAGE_INDEXintent(in) The ID of the source remote image; must be a positive number. SRC_REFS intent(in) The references to apply to the remote structure to get the data. DST_KIND intent(in) Kind of the destination argument SRC_KIND intent(in) Kind of the source argument MAY_REQUIRE_TMPintent(in) The variable is ‘false’ when it is known at compile time that the DEST and SRC either cannot overlap or overlap (fully or partially) such that walking SRC and DEST in elementwise order (honoring the stride value) does not lead to wrong results. Otherwise, the value is ‘true’. DST_STAT intent(out) when non-‘NULL’ give the result of the send-operation, i.e., zero on success and nonzero on error. When ‘NULL’ and an error occurs, then an error message is printed and the program is terminated. SRC_STAT intent(out) When non-‘NULL’ give the result of the get-operation, i.e., zero on success and nonzero on error. When ‘NULL’ and an error occurs, then an error message is printed and the program is terminated. DST_TYPE intent(in) Give the type of the destination. When the destination is not an array, than the precise type, e.g. of a component in a derived type, is not known, but provided here. SRC_TYPE intent(in) Give the type of the source. When the source is not an array, than the precise type, e.g. of a component in a derived type, is not known, but provided here. _Notes_: It is permitted to have the same image index for both SRC_IMAGE_INDEX and DST_IMAGE_INDEX; the memory of the send-to and the send-from might (partially) overlap in that case. The implementation has to take care that it handles this case, e.g. using ‘memmove’ which handles (partially) overlapping memory. If MAY_REQUIRE_TMP is true, the library might additionally create a temporary variable, unless additional checks show that this is not required (e.g. because walking backward is possible or because both arrays are contiguous and ‘memmove’ takes care of overlap issues). Note that the assignment of a scalar to an array is permitted. In addition, the library has to handle numeric-type conversion and for strings, padding and different character kinds. Because of the more complicated references possible some operations may be unsupported by certain libraries. The library is expected to issue a precise error message why the operation is not permitted.  File: gfortran.info, Node: _gfortran_caf_lock, Next: _gfortran_caf_unlock, Prev: _gfortran_caf_sendget_by_ref, Up: Function ABI Documentation 7.2.18 ‘_gfortran_caf_lock’ -- Locking a lock variable ------------------------------------------------------ _Synopsis_: ‘void _gfortran_caf_lock (caf_token_t token, size_t index, int image_index, int *acquired_lock, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Acquire a lock on the given image on a scalar locking variable or for the given array element for an array-valued variable. If the ACQUIRED_LOCK is ‘NULL’, the function returns after having obtained the lock. If it is non-‘NULL’, then ACQUIRED_LOCK is assigned the value true (one) when the lock could be obtained and false (zero) otherwise. Locking a lock variable that has already been locked by the same image is an error. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. INDEX intent(in) Array index; first array index is 0. For scalars, it is always 0. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number. ACQUIRED_LOCKintent(out) If not NULL, it returns whether lock could be obtained. STAT intent(out) Stores the STAT=; may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: This function is also called for critical blocks; for those, the array index is always zero and the image index is one. Libraries are permitted to use other images for critical-block locking variables.  File: gfortran.info, Node: _gfortran_caf_unlock, Next: _gfortran_caf_event_post, Prev: _gfortran_caf_lock, Up: Function ABI Documentation 7.2.19 ‘_gfortran_caf_lock’ -- Unlocking a lock variable -------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_unlock (caf_token_t token, size_t index, int image_index, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Release a lock on the given image on a scalar locking variable or for the given array element for an array-valued variable. Unlocking a lock variable that is unlocked or has been locked by a different image is an error. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. INDEX intent(in) Array index; first array index is 0. For scalars, it is always 0. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number. STAT intent(out) For allocatable coarrays, stores the STAT=; may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: This function is also called for critical block; for those, the array index is always zero and the image index is one. Libraries are permitted to use other images for critical-block locking variables.  File: gfortran.info, Node: _gfortran_caf_event_post, Next: _gfortran_caf_event_wait, Prev: _gfortran_caf_unlock, Up: Function ABI Documentation 7.2.20 ‘_gfortran_caf_event_post’ -- Post an event -------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_event_post (caf_token_t token, size_t index, int image_index, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Increment the event count of the specified event variable. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. INDEX intent(in) Array index; first array index is 0. For scalars, it is always 0. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number; zero indicates the current image, when accessed noncoindexed. STAT intent(out) Stores the STAT=; may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: This acts like an atomic add of one to the remote image's event variable. The statement is an image-control statement but does not imply sync memory. Still, all preceding push communications of this image to the specified remote image have to be completed before ‘event_wait’ on the remote image returns.  File: gfortran.info, Node: _gfortran_caf_event_wait, Next: _gfortran_caf_event_query, Prev: _gfortran_caf_event_post, Up: Function ABI Documentation 7.2.21 ‘_gfortran_caf_event_wait’ -- Wait that an event occurred ---------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_event_wait (caf_token_t token, size_t index, int until_count, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Wait until the event count has reached at least the specified UNTIL_COUNT; if so, atomically decrement the event variable by this amount and return. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. INDEX intent(in) Array index; first array index is 0. For scalars, it is always 0. UNTIL_COUNT intent(in) The number of events that have to be available before the function returns. STAT intent(out) Stores the STAT=; may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: This function only operates on a local coarray. It acts like a loop checking atomically the value of the event variable, breaking if the value is greater or equal the requested number of counts. Before the function returns, the event variable has to be decremented by the requested UNTIL_COUNT value. A possible implementation would be a busy loop for a certain number of spins (possibly depending on the number of threads relative to the number of available cores) followed by another waiting strategy such as a sleeping wait (possibly with an increasing number of sleep time) or, if possible, a futex wait. The statement is an image-control statement but does not imply sync memory. Still, all preceding push communications of this image to the specified remote image have to be completed before ‘event_wait’ on the remote image returns.  File: gfortran.info, Node: _gfortran_caf_event_query, Next: _gfortran_caf_sync_all, Prev: _gfortran_caf_event_wait, Up: Function ABI Documentation 7.2.22 ‘_gfortran_caf_event_query’ -- Query event count ------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_event_query (caf_token_t token, size_t index, int image_index, int *count, int *stat)’ _Description_: Return the event count of the specified event variable. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. INDEX intent(in) Array index; first array index is 0. For scalars, it is always 0. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number; zero indicates the current image when accessed noncoindexed. COUNT intent(out) The number of events currently posted to the event variable. STAT intent(out) Stores the STAT=; may be NULL. _Notes_: The typical use is to check the local event variable to only call ‘event_wait’ when the data is available. However, a coindexed variable is permitted; there is no ordering or synchronization implied. It acts like an atomic fetch of the value of the event variable.  File: gfortran.info, Node: _gfortran_caf_sync_all, Next: _gfortran_caf_sync_images, Prev: _gfortran_caf_event_query, Up: Function ABI Documentation 7.2.23 ‘_gfortran_caf_sync_all’ -- All-image barrier ---------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_sync_all (int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Synchronization of all images in the current team; the program only continues on a given image after this function has been called on all images of the current team. Additionally, it ensures that all pending data transfers of previous segment have completed. _Arguments_: STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg  File: gfortran.info, Node: _gfortran_caf_sync_images, Next: _gfortran_caf_sync_memory, Prev: _gfortran_caf_sync_all, Up: Function ABI Documentation 7.2.24 ‘_gfortran_caf_sync_images’ -- Barrier for selected images ----------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_sync_images (int count, int images[], int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Synchronization between the specified images; the program only continues on a given image after this function has been called on all images specified for that image. Note that one image can wait for all other images in the current team (e.g. via ‘sync images(*)’) while those only wait for that specific image. Additionally, ‘sync images’ ensures that all pending data transfers of previous segments have completed. _Arguments_: COUNT intent(in) The number of images that are provided in the next argument. For a zero-sized array, the value is zero. For ‘sync images (*)’, the value is -1. IMAGES intent(in) An array with the images provided by the user. If COUNT is zero, a NULL pointer is passed. STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg  File: gfortran.info, Node: _gfortran_caf_sync_memory, Next: _gfortran_caf_error_stop, Prev: _gfortran_caf_sync_images, Up: Function ABI Documentation 7.2.25 ‘_gfortran_caf_sync_memory’ -- Wait for completion of segment-memory operations -------------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_sync_memory (int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Acts as optimization barrier between different segments. It also ensures that all pending memory operations of this image have been completed. _Arguments_: STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: A simple implementation could be ‘__asm__ __volatile__ ("":::"memory")’ to prevent code movements.  File: gfortran.info, Node: _gfortran_caf_error_stop, Next: _gfortran_caf_error_stop_str, Prev: _gfortran_caf_sync_memory, Up: Function ABI Documentation 7.2.26 ‘_gfortran_caf_error_stop’ -- Error termination with exit code --------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_error_stop (int error)’ _Description_: Invoked for an ‘ERROR STOP’ statement that has an integer argument. The function should terminate the program with the specified exit code. _Arguments_: ERROR intent(in) The exit status to be used.  File: gfortran.info, Node: _gfortran_caf_error_stop_str, Next: _gfortran_caf_fail_image, Prev: _gfortran_caf_error_stop, Up: Function ABI Documentation 7.2.27 ‘_gfortran_caf_error_stop_str’ -- Error termination with string ---------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_error_stop (const char *string, size_t len)’ _Description_: Invoked for an ‘ERROR STOP’ statement that has a string as argument. The function should terminate the program with a nonzero-exit code. _Arguments_: STRING intent(in) the error message (not zero terminated) LEN intent(in) the length of the string  File: gfortran.info, Node: _gfortran_caf_fail_image, Next: _gfortran_caf_atomic_define, Prev: _gfortran_caf_error_stop_str, Up: Function ABI Documentation 7.2.28 ‘_gfortran_caf_fail_image’ -- Mark the image failed and end its execution -------------------------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_fail_image ()’ _Description_: Invoked for an ‘FAIL IMAGE’ statement. The function should terminate the current image. _Notes_: This function follows TS18508.  File: gfortran.info, Node: _gfortran_caf_atomic_define, Next: _gfortran_caf_atomic_ref, Prev: _gfortran_caf_fail_image, Up: Function ABI Documentation 7.2.29 ‘_gfortran_caf_atomic_define’ -- Atomic variable assignment ------------------------------------------------------------------ _Synopsis_: ‘void _gfortran_caf_atomic_define (caf_token_t token, size_t offset, int image_index, void *value, int *stat, int type, int kind)’ _Description_: Assign atomically a value to an integer or logical variable. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. OFFSET intent(in) The number of bytes the actual data is shifted compared to the base address of the coarray. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number; zero indicates the current image when used noncoindexed. VALUE intent(in) the value to be assigned, passed by reference STAT intent(out) Stores the status STAT= and may be NULL. TYPE intent(in) The data type, i.e. ‘BT_INTEGER’ (1) or ‘BT_LOGICAL’ (2). KIND intent(in) The kind value (only 4; always ‘int’)  File: gfortran.info, Node: _gfortran_caf_atomic_ref, Next: _gfortran_caf_atomic_cas, Prev: _gfortran_caf_atomic_define, Up: Function ABI Documentation 7.2.30 ‘_gfortran_caf_atomic_ref’ -- Atomic variable reference -------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_atomic_ref (caf_token_t token, size_t offset, int image_index, void *value, int *stat, int type, int kind)’ _Description_: Reference atomically a value of a kind-4 integer or logical variable. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. OFFSET intent(in) The number of bytes the actual data is shifted compared to the base address of the coarray. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number; zero indicates the current image when used noncoindexed. VALUE intent(out) The variable assigned the atomically referenced variable. STAT intent(out) Stores the status STAT= and may be NULL. TYPE the data type, i.e. ‘BT_INTEGER’ (1) or ‘BT_LOGICAL’ (2). KIND The kind value (only 4; always ‘int’)  File: gfortran.info, Node: _gfortran_caf_atomic_cas, Next: _gfortran_caf_atomic_op, Prev: _gfortran_caf_atomic_ref, Up: Function ABI Documentation 7.2.31 ‘_gfortran_caf_atomic_cas’ -- Atomic compare and swap ------------------------------------------------------------ _Synopsis_: ‘void _gfortran_caf_atomic_cas (caf_token_t token, size_t offset, int image_index, void *old, void *compare, void *new_val, int *stat, int type, int kind)’ _Description_: Atomic compare and swap of a kind-4 integer or logical variable. Assigns atomically the specified value to the atomic variable, if the latter has the value specified by the passed condition value. _Arguments_: TOKEN intent(in) An opaque pointer identifying the coarray. OFFSET intent(in) The number of bytes the actual data is shifted compared to the base address of the coarray. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number; zero indicates the current image when used noncoindexed. OLD intent(out) The value the atomic variable had just before the cas operation. COMPARE intent(in) The value used for comparison. NEW_VAL intent(in) The new value for the atomic variable, assigned to the atomic variable, if ‘compare’ equals the value of the atomic variable. STAT intent(out) Stores the status STAT= and may be NULL. TYPE intent(in) the data type, i.e. ‘BT_INTEGER’ (1) or ‘BT_LOGICAL’ (2). KIND intent(in) The kind value (only 4; always ‘int’)  File: gfortran.info, Node: _gfortran_caf_atomic_op, Next: _gfortran_caf_co_broadcast, Prev: _gfortran_caf_atomic_cas, Up: Function ABI Documentation 7.2.32 ‘_gfortran_caf_atomic_op’ -- Atomic operation ---------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_atomic_op (int op, caf_token_t token, size_t offset, int image_index, void *value, void *old, int *stat, int type, int kind)’ _Description_: Apply an operation atomically to an atomic integer or logical variable. After the operation, OLD contains the value just before the operation, which, respectively, adds (GFC_CAF_ATOMIC_ADD) atomically the ‘value’ to the atomic integer variable or does a bitwise AND, OR or exclusive OR between the atomic variable and VALUE; the result is then stored in the atomic variable. _Arguments_: OP intent(in) the operation to be performed; possible values ‘GFC_CAF_ATOMIC_ADD’ (1), ‘GFC_CAF_ATOMIC_AND’ (2), ‘GFC_CAF_ATOMIC_OR’ (3), ‘GFC_CAF_ATOMIC_XOR’ (4). TOKEN intent(in) An opaque pointer identifying the coarray. OFFSET intent(in) The number of bytes the actual data is shifted compared to the base address of the coarray. IMAGE_INDEX intent(in) The ID of the remote image; must be a positive number; zero indicates the current image when used noncoindexed. OLD intent(out) The value the atomic variable had just before the atomic operation. VAL intent(in) The new value for the atomic variable, assigned to the atomic variable, if ‘compare’ equals the value of the atomic variable. STAT intent(out) Stores the status STAT= and may be NULL. TYPE intent(in) the data type, i.e. ‘BT_INTEGER’ (1) or ‘BT_LOGICAL’ (2) KIND intent(in) the kind value (only 4; always ‘int’)  File: gfortran.info, Node: _gfortran_caf_co_broadcast, Next: _gfortran_caf_co_max, Prev: _gfortran_caf_atomic_op, Up: Function ABI Documentation 7.2.33 ‘_gfortran_caf_co_broadcast’ -- Sending data to all images ----------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_co_broadcast (gfc_descriptor_t *a, int source_image, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Distribute a value from a given image to all other images in the team. Has to be called collectively. _Arguments_: A intent(inout) An array descriptor with the data to be broadcasted (on SOURCE_IMAGE) or to be received (other images). SOURCE_IMAGEintent(in) The ID of the image from which the data should be broadcasted. STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg.  File: gfortran.info, Node: _gfortran_caf_co_max, Next: _gfortran_caf_co_min, Prev: _gfortran_caf_co_broadcast, Up: Function ABI Documentation 7.2.34 ‘_gfortran_caf_co_max’ -- Collective maximum reduction ------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_co_max (gfc_descriptor_t *a, int result_image, int *stat, char *errmsg, int a_len, size_t errmsg_len)’ _Description_: Calculates for each array element of the variable A the maximum value for that element in the current team; if RESULT_IMAGE has the value 0, the result shall be stored on all images, otherwise, only on the specified image. This function operates on numeric values and character strings. _Arguments_: A intent(inout) An array descriptor for the data to be processed. On the destination image(s) the result overwrites the old content. RESULT_IMAGEintent(in) The ID of the image to which the reduced value should be copied to; if zero, it has to be copied to all images. STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. A_LEN intent(in) the string length of argument A ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: If RESULT_IMAGE is nonzero, the data in the array descriptor A on all images except of the specified one become undefined; hence, the library may make use of this.  File: gfortran.info, Node: _gfortran_caf_co_min, Next: _gfortran_caf_co_sum, Prev: _gfortran_caf_co_max, Up: Function ABI Documentation 7.2.35 ‘_gfortran_caf_co_min’ -- Collective minimum reduction ------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_co_min (gfc_descriptor_t *a, int result_image, int *stat, char *errmsg, int a_len, size_t errmsg_len)’ _Description_: Calculates for each array element of the variable A the minimum value for that element in the current team; if RESULT_IMAGE has the value 0, the result shall be stored on all images, otherwise, only on the specified image. This function operates on numeric values and character strings. _Arguments_: A intent(inout) An array descriptor for the data to be processed. On the destination image(s) the result overwrites the old content. RESULT_IMAGEintent(in) The ID of the image to which the reduced value should be copied to; if zero, it has to be copied to all images. STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. A_LEN intent(in) the string length of argument A ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: If RESULT_IMAGE is nonzero, the data in the array descriptor A on all images except of the specified one become undefined; hence, the library may make use of this.  File: gfortran.info, Node: _gfortran_caf_co_sum, Next: _gfortran_caf_co_reduce, Prev: _gfortran_caf_co_min, Up: Function ABI Documentation 7.2.36 ‘_gfortran_caf_co_sum’ -- Collective summing reduction ------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_co_sum (gfc_descriptor_t *a, int result_image, int *stat, char *errmsg, size_t errmsg_len)’ _Description_: Calculates for each array element of the variable A the sum of all values for that element in the current team; if RESULT_IMAGE has the value 0, the result shall be stored on all images, otherwise, only on the specified image. This function operates on numeric values only. _Arguments_: A intent(inout) An array descriptor with the data to be processed. On the destination image(s) the result overwrites the old content. RESULT_IMAGEintent(in) The ID of the image to which the reduced value should be copied to; if zero, it has to be copied to all images. STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: If RESULT_IMAGE is nonzero, the data in the array descriptor A on all images except of the specified one become undefined; hence, the library may make use of this.  File: gfortran.info, Node: _gfortran_caf_co_reduce, Prev: _gfortran_caf_co_sum, Up: Function ABI Documentation 7.2.37 ‘_gfortran_caf_co_reduce’ -- Generic collective reduction ---------------------------------------------------------------- _Synopsis_: ‘void _gfortran_caf_co_reduce (gfc_descriptor_t *a, void * (*opr) (void *, void *), int opr_flags, int result_image, int *stat, char *errmsg, int a_len, size_t errmsg_len)’ _Description_: Calculates for each array element of the variable A the reduction value for that element in the current team; if RESULT_IMAGE has the value 0, the result shall be stored on all images, otherwise, only on the specified image. The OPR is a pure function doing a mathematically commutative and associative operation. The OPR_FLAGS denote the following; the values are bitwise ored. ‘GFC_CAF_BYREF’ (1) if the result should be returned by reference; ‘GFC_CAF_HIDDENLEN’ (2) whether the result and argument string lengths shall be specified as hidden arguments; ‘GFC_CAF_ARG_VALUE’ (4) whether the arguments shall be passed by value, ‘GFC_CAF_ARG_DESC’ (8) whether the arguments shall be passed by descriptor. _Arguments_: A intent(inout) An array descriptor with the data to be processed. On the destination image(s) the result overwrites the old content. OPR intent(in) Function pointer to the reduction function OPR_FLAGS intent(in) Flags regarding the reduction function RESULT_IMAGEintent(in) The ID of the image to which the reduced value should be copied to; if zero, it has to be copied to all images. STAT intent(out) Stores the status STAT= and may be NULL. ERRMSG intent(out) When an error occurs, this is set to an error message; may be NULL. A_LEN intent(in) the string length of argument A ERRMSG_LEN intent(in) the buffer size of errmsg _Notes_: If RESULT_IMAGE is nonzero, the data in the array descriptor A on all images except of the specified one become undefined; hence, the library may make use of this. For character arguments, the result is passed as first argument, followed by the result string length, next come the two string arguments, followed by the two hidden string length arguments. With C binding, there are no hidden arguments and by-reference passing and either only a single character is passed or an array descriptor.  File: gfortran.info, Node: Intrinsic Procedures, Next: Intrinsic Modules, Prev: Coarray Programming, Up: Top 8 Intrinsic Procedures ********************** * Menu: * Introduction: Introduction to Intrinsics * ‘ABORT’: ABORT, Abort the program * ‘ABS’: ABS, Absolute value * ‘ACCESS’: ACCESS, Checks file access modes * ‘ACHAR’: ACHAR, Character in ASCII collating sequence * ‘ACOS’: ACOS, Arccosine function * ‘ACOSD’: ACOSD, Arccosine function, degrees * ‘ACOSH’: ACOSH, Inverse hyperbolic cosine function * ‘ADJUSTL’: ADJUSTL, Left adjust a string * ‘ADJUSTR’: ADJUSTR, Right adjust a string * ‘AIMAG’: AIMAG, Imaginary part of complex number * ‘AINT’: AINT, Truncate to a whole number * ‘ALARM’: ALARM, Set an alarm clock * ‘ALL’: ALL, Determine if all values are true * ‘ALLOCATED’: ALLOCATED, Status of allocatable entity * ‘AND’: AND, Bitwise logical AND * ‘ANINT’: ANINT, Nearest whole number * ‘ANY’: ANY, Determine if any values are true * ‘ASIN’: ASIN, Arcsine function * ‘ASIND’: ASIND, Arcsine function, degrees * ‘ASINH’: ASINH, Inverse hyperbolic sine function * ‘ASSOCIATED’: ASSOCIATED, Status of a pointer or pointer/target pair * ‘ATAN’: ATAN, Arctangent function * ‘ATAND’: ATAND, Arctangent function, degrees * ‘ATAN2’: ATAN2, Arctangent function * ‘ATAN2D’: ATAN2D, Arctangent function, degrees * ‘ATANH’: ATANH, Inverse hyperbolic tangent function * ‘ATOMIC_ADD’: ATOMIC_ADD, Atomic ADD operation * ‘ATOMIC_AND’: ATOMIC_AND, Atomic bitwise AND operation * ‘ATOMIC_CAS’: ATOMIC_CAS, Atomic compare and swap * ‘ATOMIC_DEFINE’: ATOMIC_DEFINE, Setting a variable atomically * ‘ATOMIC_FETCH_ADD’: ATOMIC_FETCH_ADD, Atomic ADD operation with prior fetch * ‘ATOMIC_FETCH_AND’: ATOMIC_FETCH_AND, Atomic bitwise AND operation with prior fetch * ‘ATOMIC_FETCH_OR’: ATOMIC_FETCH_OR, Atomic bitwise OR operation with prior fetch * ‘ATOMIC_FETCH_XOR’: ATOMIC_FETCH_XOR, Atomic bitwise XOR operation with prior fetch * ‘ATOMIC_OR’: ATOMIC_OR, Atomic bitwise OR operation * ‘ATOMIC_REF’: ATOMIC_REF, Obtaining the value of a variable atomically * ‘ATOMIC_XOR’: ATOMIC_XOR, Atomic bitwise OR operation * ‘BACKTRACE’: BACKTRACE, Show a backtrace * ‘BESSEL_J0’: BESSEL_J0, Bessel function of the first kind of order 0 * ‘BESSEL_J1’: BESSEL_J1, Bessel function of the first kind of order 1 * ‘BESSEL_JN’: BESSEL_JN, Bessel function of the first kind * ‘BESSEL_Y0’: BESSEL_Y0, Bessel function of the second kind of order 0 * ‘BESSEL_Y1’: BESSEL_Y1, Bessel function of the second kind of order 1 * ‘BESSEL_YN’: BESSEL_YN, Bessel function of the second kind * ‘BGE’: BGE, Bitwise greater than or equal to * ‘BGT’: BGT, Bitwise greater than * ‘BIT_SIZE’: BIT_SIZE, Bit size inquiry function * ‘BLE’: BLE, Bitwise less than or equal to * ‘BLT’: BLT, Bitwise less than * ‘BTEST’: BTEST, Bit test function * ‘C_ASSOCIATED’: C_ASSOCIATED, Status of a C pointer * ‘C_F_POINTER’: C_F_POINTER, Convert C into Fortran pointer * ‘C_F_PROCPOINTER’: C_F_PROCPOINTER, Convert C into Fortran procedure pointer * ‘C_FUNLOC’: C_FUNLOC, Obtain the C address of a procedure * ‘C_LOC’: C_LOC, Obtain the C address of an object * ‘C_SIZEOF’: C_SIZEOF, Size in bytes of an expression * ‘CEILING’: CEILING, Integer ceiling function * ‘CHAR’: CHAR, Integer-to-character conversion function * ‘CHDIR’: CHDIR, Change working directory * ‘CHMOD’: CHMOD, Change access permissions of files * ‘CMPLX’: CMPLX, Complex conversion function * ‘CO_BROADCAST’: CO_BROADCAST, Copy a value to all images the current set of images * ‘CO_MAX’: CO_MAX, Maximal value on the current set of images * ‘CO_MIN’: CO_MIN, Minimal value on the current set of images * ‘CO_REDUCE’: CO_REDUCE, Reduction of values on the current set of images * ‘CO_SUM’: CO_SUM, Sum of values on the current set of images * ‘COMMAND_ARGUMENT_COUNT’: COMMAND_ARGUMENT_COUNT, Get number of command line arguments * ‘COMPILER_OPTIONS’: COMPILER_OPTIONS, Options passed to the compiler * ‘COMPILER_VERSION’: COMPILER_VERSION, Compiler version string * ‘COMPLEX’: COMPLEX, Complex conversion function * ‘CONJG’: CONJG, Complex conjugate function * ‘COS’: COS, Cosine function * ‘COSD’: COSD, Cosine function, degrees * ‘COSH’: COSH, Hyperbolic cosine function * ‘COTAN’: COTAN, Cotangent function * ‘COTAND’: COTAND, Cotangent function, degrees * ‘COUNT’: COUNT, Count occurrences of TRUE in an array * ‘CPU_TIME’: CPU_TIME, CPU time subroutine * ‘CSHIFT’: CSHIFT, Circular shift elements of an array * ‘CTIME’: CTIME, Subroutine (or function) to convert a time into a string * ‘DATE_AND_TIME’: DATE_AND_TIME, Date and time subroutine * ‘DBLE’: DBLE, Double precision conversion function * ‘DCMPLX’: DCMPLX, Double complex conversion function * ‘DIGITS’: DIGITS, Significant digits function * ‘DIM’: DIM, Positive difference * ‘DOT_PRODUCT’: DOT_PRODUCT, Dot product function * ‘DPROD’: DPROD, Double product function * ‘DREAL’: DREAL, Double real part function * ‘DSHIFTL’: DSHIFTL, Combined left shift * ‘DSHIFTR’: DSHIFTR, Combined right shift * ‘DTIME’: DTIME, Execution time subroutine (or function) * ‘EOSHIFT’: EOSHIFT, End-off shift elements of an array * ‘EPSILON’: EPSILON, Epsilon function * ‘ERF’: ERF, Error function * ‘ERFC’: ERFC, Complementary error function * ‘ERFC_SCALED’: ERFC_SCALED, Exponentially-scaled complementary error function * ‘ETIME’: ETIME, Execution time subroutine (or function) * ‘EVENT_QUERY’: EVENT_QUERY, Query whether a coarray event has occurred * ‘EXECUTE_COMMAND_LINE’: EXECUTE_COMMAND_LINE, Execute a shell command * ‘EXIT’: EXIT, Exit the program with status. * ‘EXP’: EXP, Exponential function * ‘EXPONENT’: EXPONENT, Exponent function * ‘EXTENDS_TYPE_OF’: EXTENDS_TYPE_OF, Query dynamic type for extension * ‘FDATE’: FDATE, Subroutine (or function) to get the current time as a string * ‘FGET’: FGET, Read a single character in stream mode from stdin * ‘FGETC’: FGETC, Read a single character in stream mode * ‘FINDLOC’: FINDLOC, Search an array for a value * ‘FLOOR’: FLOOR, Integer floor function * ‘FLUSH’: FLUSH, Flush I/O unit(s) * ‘FNUM’: FNUM, File number function * ‘FPUT’: FPUT, Write a single character in stream mode to stdout * ‘FPUTC’: FPUTC, Write a single character in stream mode * ‘FRACTION’: FRACTION, Fractional part of the model representation * ‘FREE’: FREE, Memory de-allocation subroutine * ‘FSEEK’: FSEEK, Low level file positioning subroutine * ‘FSTAT’: FSTAT, Get file status * ‘FTELL’: FTELL, Current stream position * ‘GAMMA’: GAMMA, Gamma function * ‘GERROR’: GERROR, Get last system error message * ‘GETARG’: GETARG, Get command line arguments * ‘GET_COMMAND’: GET_COMMAND, Get the entire command line * ‘GET_COMMAND_ARGUMENT’: GET_COMMAND_ARGUMENT, Get command line arguments * ‘GETCWD’: GETCWD, Get current working directory * ‘GETENV’: GETENV, Get an environmental variable * ‘GET_ENVIRONMENT_VARIABLE’: GET_ENVIRONMENT_VARIABLE, Get an environmental variable * ‘GETGID’: GETGID, Group ID function * ‘GETLOG’: GETLOG, Get login name * ‘GETPID’: GETPID, Process ID function * ‘GETUID’: GETUID, User ID function * ‘GMTIME’: GMTIME, Convert time to GMT info * ‘HOSTNM’: HOSTNM, Get system host name * ‘HUGE’: HUGE, Largest number of a kind * ‘HYPOT’: HYPOT, Euclidean distance function * ‘IACHAR’: IACHAR, Code in ASCII collating sequence * ‘IALL’: IALL, Bitwise AND of array elements * ‘IAND’: IAND, Bitwise logical and * ‘IANY’: IANY, Bitwise OR of array elements * ‘IARGC’: IARGC, Get the number of command line arguments * ‘IBCLR’: IBCLR, Clear bit * ‘IBITS’: IBITS, Bit extraction * ‘IBSET’: IBSET, Set bit * ‘ICHAR’: ICHAR, Character-to-integer conversion function * ‘IDATE’: IDATE, Current local time (day/month/year) * ‘IEOR’: IEOR, Bitwise logical exclusive or * ‘IERRNO’: IERRNO, Function to get the last system error number * ‘IMAGE_INDEX’: IMAGE_INDEX, Cosubscript to image index conversion * ‘INDEX’: INDEX intrinsic, Position of a substring within a string * ‘INT’: INT, Convert to integer type * ‘INT2’: INT2, Convert to 16-bit integer type * ‘INT8’: INT8, Convert to 64-bit integer type * ‘IOR’: IOR, Bitwise logical or * ‘IPARITY’: IPARITY, Bitwise XOR of array elements * ‘IRAND’: IRAND, Integer pseudo-random number * ‘IS_CONTIGUOUS’: IS_CONTIGUOUS, Test whether an array is contiguous * ‘IS_IOSTAT_END’: IS_IOSTAT_END, Test for end-of-file value * ‘IS_IOSTAT_EOR’: IS_IOSTAT_EOR, Test for end-of-record value * ‘ISATTY’: ISATTY, Whether a unit is a terminal device * ‘ISHFT’: ISHFT, Shift bits * ‘ISHFTC’: ISHFTC, Shift bits circularly * ‘ISNAN’: ISNAN, Tests for a NaN * ‘ITIME’: ITIME, Current local time (hour/minutes/seconds) * ‘KILL’: KILL, Send a signal to a process * ‘KIND’: KIND, Kind of an entity * ‘LBOUND’: LBOUND, Lower dimension bounds of an array * ‘LCOBOUND’: LCOBOUND, Lower codimension bounds of an array * ‘LEADZ’: LEADZ, Number of leading zero bits of an integer * ‘LEN’: LEN, Length of a character entity * ‘LEN_TRIM’: LEN_TRIM, Length of a character entity without trailing blank characters * ‘LGE’: LGE, Lexical greater than or equal * ‘LGT’: LGT, Lexical greater than * ‘LINK’: LINK, Create a hard link * ‘LLE’: LLE, Lexical less than or equal * ‘LLT’: LLT, Lexical less than * ‘LNBLNK’: LNBLNK, Index of the last non-blank character in a string * ‘LOC’: LOC, Returns the address of a variable * ‘LOG’: LOG, Logarithm function * ‘LOG10’: LOG10, Base 10 logarithm function * ‘LOG_GAMMA’: LOG_GAMMA, Logarithm of the Gamma function * ‘LOGICAL’: LOGICAL, Convert to logical type * ‘LSHIFT’: LSHIFT, Left shift bits * ‘LSTAT’: LSTAT, Get file status * ‘LTIME’: LTIME, Convert time to local time info * ‘MALLOC’: MALLOC, Dynamic memory allocation function * ‘MASKL’: MASKL, Left justified mask * ‘MASKR’: MASKR, Right justified mask * ‘MATMUL’: MATMUL, matrix multiplication * ‘MAX’: MAX, Maximum value of an argument list * ‘MAXEXPONENT’: MAXEXPONENT, Maximum exponent of a real kind * ‘MAXLOC’: MAXLOC, Location of the maximum value within an array * ‘MAXVAL’: MAXVAL, Maximum value of an array * ‘MCLOCK’: MCLOCK, Time function * ‘MCLOCK8’: MCLOCK8, Time function (64-bit) * ‘MERGE’: MERGE, Merge arrays * ‘MERGE_BITS’: MERGE_BITS, Merge of bits under mask * ‘MIN’: MIN, Minimum value of an argument list * ‘MINEXPONENT’: MINEXPONENT, Minimum exponent of a real kind * ‘MINLOC’: MINLOC, Location of the minimum value within an array * ‘MINVAL’: MINVAL, Minimum value of an array * ‘MOD’: MOD, Remainder function * ‘MODULO’: MODULO, Modulo function * ‘MOVE_ALLOC’: MOVE_ALLOC, Move allocation from one object to another * ‘MVBITS’: MVBITS, Move bits from one integer to another * ‘NEAREST’: NEAREST, Nearest representable number * ‘NEW_LINE’: NEW_LINE, New line character * ‘NINT’: NINT, Nearest whole number * ‘NORM2’: NORM2, Euclidean vector norm * ‘NOT’: NOT, Logical negation * ‘NULL’: NULL, Function that returns an disassociated pointer * ‘NUM_IMAGES’: NUM_IMAGES, Number of images * ‘OR’: OR, Bitwise logical OR * ‘OUT_OF_RANGE’: OUT_OF_RANGE, Range check for numerical conversion * ‘PACK’: PACK, Pack an array into an array of rank one * ‘PARITY’: PARITY, Reduction with exclusive OR * ‘PERROR’: PERROR, Print system error message * ‘POPCNT’: POPCNT, Number of bits set * ‘POPPAR’: POPPAR, Parity of the number of bits set * ‘PRECISION’: PRECISION, Decimal precision of a real kind * ‘PRESENT’: PRESENT, Determine whether an optional dummy argument is specified * ‘PRODUCT’: PRODUCT, Product of array elements * ‘RADIX’: RADIX, Base of a data model * ‘RAN’: RAN, Real pseudo-random number * ‘RAND’: RAND, Real pseudo-random number * ‘RANDOM_INIT’: RANDOM_INIT, Initialize pseudo-random number generator * ‘RANDOM_NUMBER’: RANDOM_NUMBER, Pseudo-random number * ‘RANDOM_SEED’: RANDOM_SEED, Initialize a pseudo-random number sequence * ‘RANGE’: RANGE, Decimal exponent range * ‘RANK’ : RANK, Rank of a data object * ‘REAL’: REAL, Convert to real type * ‘RENAME’: RENAME, Rename a file * ‘REPEAT’: REPEAT, Repeated string concatenation * ‘RESHAPE’: RESHAPE, Function to reshape an array * ‘RRSPACING’: RRSPACING, Reciprocal of the relative spacing * ‘RSHIFT’: RSHIFT, Right shift bits * ‘SAME_TYPE_AS’: SAME_TYPE_AS, Query dynamic types for equality * ‘SCALE’: SCALE, Scale a real value * ‘SCAN’: SCAN, Scan a string for the presence of a set of characters * ‘SECNDS’: SECNDS, Time function * ‘SECOND’: SECOND, CPU time function * ‘SELECTED_CHAR_KIND’: SELECTED_CHAR_KIND, Choose character kind * ‘SELECTED_INT_KIND’: SELECTED_INT_KIND, Choose integer kind * ‘SELECTED_LOGICAL_KIND’: SELECTED_LOGICAL_KIND, Choose logical kind * ‘SELECTED_REAL_KIND’: SELECTED_REAL_KIND, Choose real kind * ‘SELECTED_UNSIGNED_KIND’: SELECTED_UNSIGNED_KIND, Chose unsigned kind * ‘SET_EXPONENT’: SET_EXPONENT, Set the exponent of the model * ‘SHAPE’: SHAPE, Determine the shape of an array * ‘SHIFTA’: SHIFTA, Right shift with fill * ‘SHIFTL’: SHIFTL, Left shift * ‘SHIFTR’: SHIFTR, Right shift * ‘SIGN’: SIGN, Sign copying function * ‘SIGNAL’: SIGNAL, Signal handling subroutine (or function) * ‘SIN’: SIN, Sine function * ‘SIND’: SIND, Sine function, degrees * ‘SINH’: SINH, Hyperbolic sine function * ‘SIZE’: SIZE, Function to determine the size of an array * ‘SIZEOF’: SIZEOF, Determine the size in bytes of an expression * ‘SLEEP’: SLEEP, Sleep for the specified number of seconds * ‘SPACING’: SPACING, Smallest distance between two numbers of a given type * ‘SPREAD’: SPREAD, Add a dimension to an array * ‘SQRT’: SQRT, Square-root function * ‘SRAND’: SRAND, Reinitialize the random number generator * ‘STAT’: STAT, Get file status * ‘STORAGE_SIZE’: STORAGE_SIZE, Storage size in bits * ‘SUM’: SUM, Sum of array elements * ‘SYMLNK’: SYMLNK, Create a symbolic link * ‘SYSTEM’: SYSTEM, Execute a shell command * ‘SYSTEM_CLOCK’: SYSTEM_CLOCK, Time function * ‘TAN’: TAN, Tangent function * ‘TAND’: TAND, Tangent function, degrees * ‘TANH’: TANH, Hyperbolic tangent function * ‘THIS_IMAGE’: THIS_IMAGE, Cosubscript index of this image * ‘TIME’: TIME, Time function * ‘TIME8’: TIME8, Time function (64-bit) * ‘TINY’: TINY, Smallest positive number of a real kind * ‘TRAILZ’: TRAILZ, Number of trailing zero bits of an integer * ‘TRANSFER’: TRANSFER, Transfer bit patterns * ‘TRANSPOSE’: TRANSPOSE, Transpose an array of rank two * ‘TRIM’: TRIM, Remove trailing blank characters of a string * ‘TTYNAM’: TTYNAM, Get the name of a terminal device * ‘UBOUND’: UBOUND, Upper dimension bounds of an array * ‘UCOBOUND’: UCOBOUND, Upper codimension bounds of an array * ‘UINT’: UINT, Convert to an unsigned integer type * ‘UMASK’: UMASK, Set the file creation mask * ‘UMASKL’: UMASKL, Unsigned left justified mask * ‘UMASKR’: UMASKR, Unsigned right justified mask * ‘UNLINK’: UNLINK, Remove a file from the file system * ‘UNPACK’: UNPACK, Unpack an array of rank one into an array * ‘VERIFY’: VERIFY, Scan a string for the absence of a set of characters * ‘XOR’: XOR, Bitwise logical exclusive or  File: gfortran.info, Node: Introduction to Intrinsics, Next: ABORT, Up: Intrinsic Procedures 8.1 Introduction to intrinsic procedures ======================================== The intrinsic procedures provided by GNU Fortran include procedures required by the Fortran 95 and later supported standards, and a set of intrinsic procedures for backwards compatibility with G77. Any conflict between a description here and a description in the Fortran standards is unintentional, and the standard(s) should be considered authoritative. The enumeration of the ‘KIND’ type parameter is processor defined in the Fortran 95 standard. GNU Fortran defines the default integer type and default real type by ‘INTEGER(KIND=4)’ and ‘REAL(KIND=4)’, respectively. The standard mandates that both data types shall have another kind that has more precision. On typical target architectures supported by ‘gfortran’, this kind type parameter is ‘KIND=8’. Hence, ‘REAL(KIND=8)’ and ‘DOUBLE PRECISION’ are equivalent. In the description of generic intrinsic procedures, the kind type parameter is specified by ‘KIND=*’, and in the description of specific names for an intrinsic procedure the kind type parameter is explicitly given (e.g., ‘REAL(KIND=4)’ or ‘REAL(KIND=8)’). Finally, for brevity the optional ‘KIND=’ syntax is omitted. Many of the intrinsic procedures take one or more optional arguments. This document follows the convention used in the Fortran 95 standard, and denotes such arguments by square brackets. GNU Fortran offers the ‘-std=’ command-line option, which can be used to restrict the set of intrinsic procedures to a given standard. By default, ‘gfortran’ sets the ‘-std=gnu’ option, and so all intrinsic procedures described here are accepted. There is one caveat. For a select group of intrinsic procedures, ‘g77’ implemented both a function and a subroutine. Both classes have been implemented in ‘gfortran’ for backwards compatibility with ‘g77’. It is noted here that these functions and subroutines cannot be intermixed in a given subprogram. In the descriptions that follow, the applicable standard for each intrinsic procedure is noted.  File: gfortran.info, Node: ABORT, Next: ABS, Prev: Introduction to Intrinsics, Up: Intrinsic Procedures 8.2 ‘ABORT’ -- Abort the program ================================ _Synopsis_: ‘CALL ABORT’ _Description_: ‘ABORT’ causes immediate termination of the program. On operating systems that support a core dump, ‘ABORT’ produces a core dump. It also prints a backtrace, unless ‘-fno-backtrace’ is given. _Class_: Subroutine _Return value_: Does not return. _Example_: program test_abort integer :: i = 1, j = 2 if (i /= j) call abort end program test_abort _Standard_: GNU extension _See also_: *note EXIT::, *note KILL::, *note BACKTRACE::  File: gfortran.info, Node: ABS, Next: ACCESS, Prev: ABORT, Up: Intrinsic Procedures 8.3 ‘ABS’ -- Absolute value =========================== _Synopsis_: ‘RESULT = ABS(A)’ _Description_: ‘ABS(A)’ computes the absolute value of ‘A’. _Class_: Elemental function _Arguments_: A The type of the argument shall be an ‘INTEGER’, ‘REAL’, or ‘COMPLEX’. _Return value_: The return value is of the same type and kind as the argument except the return value is ‘REAL’ for a ‘COMPLEX’ argument. _Example_: program test_abs integer :: i = -1 real :: x = -1.e0 complex :: z = (-1.e0,0.e0) i = abs(i) x = abs(x) x = abs(z) end program test_abs _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ABS(A)’ ‘REAL(4) A’ ‘REAL(4)’ Fortran 77 and later ‘CABS(A)’ ‘COMPLEX(4) A’ ‘REAL(4)’ Fortran 77 and later ‘DABS(A)’ ‘REAL(8) A’ ‘REAL(8)’ Fortran 77 and later ‘IABS(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ Fortran 77 and later ‘BABS(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIABS(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIABS(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIABS(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension ‘ZABS(A)’ ‘COMPLEX(8) A’ ‘REAL(8)’ GNU extension ‘CDABS(A)’ ‘COMPLEX(8) A’ ‘REAL(8)’ GNU extension _Standard_: Fortran 77 and later, has overloads that are GNU extensions  File: gfortran.info, Node: ACCESS, Next: ACHAR, Prev: ABS, Up: Intrinsic Procedures 8.4 ‘ACCESS’ -- Checks file access modes ======================================== _Synopsis_: ‘RESULT = ACCESS(NAME, MODE)’ _Description_: ‘ACCESS(NAME, MODE)’ checks whether the file NAME exists, is readable, writable or executable. Except for the executable check, ‘ACCESS’ can be replaced by Fortran 95's ‘INQUIRE’. _Class_: Inquiry function _Arguments_: NAME Scalar ‘CHARACTER’ of default kind with the file name. Trailing blank are ignored unless the character ‘achar(0)’ is present, then all characters up to and excluding ‘achar(0)’ are used as file name. MODE Scalar ‘CHARACTER’ of default kind with the file access mode, may be any concatenation of ‘"r"’ (readable), ‘"w"’ (writable) and ‘"x"’ (executable), or ‘" "’ to check for existence. _Return value_: Returns a scalar ‘INTEGER’, which is ‘0’ if the file is accessible in the given mode; otherwise or if an invalid argument has been given for ‘MODE’ the value ‘1’ is returned. _Example_: program access_test implicit none character(len=*), parameter :: file = 'test.dat' character(len=*), parameter :: file2 = 'test.dat '//achar(0) if(access(file,' ') == 0) print *, trim(file),' is exists' if(access(file,'r') == 0) print *, trim(file),' is readable' if(access(file,'w') == 0) print *, trim(file),' is writable' if(access(file,'x') == 0) print *, trim(file),' is executable' if(access(file2,'rwx') == 0) & print *, trim(file2),' is readable, writable and executable' end program access_test _Standard_: GNU extension  File: gfortran.info, Node: ACHAR, Next: ACOS, Prev: ACCESS, Up: Intrinsic Procedures 8.5 ‘ACHAR’ -- Character in ASCII collating sequence ==================================================== _Synopsis_: ‘RESULT = ACHAR(I [, KIND])’ _Description_: ‘ACHAR(I)’ returns the character located at position ‘I’ in the ASCII collating sequence. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘CHARACTER’ with a length of one. If the KIND argument is present, the return value is of the specified kind and of the default kind otherwise. _Example_: program test_achar character c c = achar(32) end program test_achar _Notes_: See *note ICHAR:: for a discussion of converting between numerical values and formatted string representations. _Standard_: Fortran 77 and later, with KIND argument Fortran 2003 and later _See also_: *note CHAR::, *note IACHAR::, *note ICHAR::  File: gfortran.info, Node: ACOS, Next: ACOSD, Prev: ACHAR, Up: Intrinsic Procedures 8.6 ‘ACOS’ -- Arccosine function ================================ _Synopsis_: ‘RESULT = ACOS(X)’ _Description_: ‘ACOS(X)’ computes the arccosine of X (inverse of ‘COS(X)’). _Class_: Elemental function _Arguments_: X The type shall either be ‘REAL’ with a magnitude that is less than or equal to one - or the type shall be ‘COMPLEX’. _Return value_: The return value is of the same type and kind as X. The real part of the result is in radians and lies in the range 0 \leq \Re \acos(x) \leq \pi. _Example_: program test_acos real(8) :: x = 0.866_8 x = acos(x) end program test_acos _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ACOS(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DACOS(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, for a complex argument Fortran 2008 or later _See also_: Inverse function: *note COS:: Degrees function: *note ACOSD::  File: gfortran.info, Node: ACOSD, Next: ACOSH, Prev: ACOS, Up: Intrinsic Procedures 8.7 ‘ACOSD’ -- Arccosine function, degrees ========================================== _Synopsis_: ‘RESULT = ACOSD(X)’ _Description_: ‘ACOSD(X)’ computes the arccosine of X in degrees (inverse of ‘COSD(X)’). _Class_: Elemental function _Arguments_: X The type shall either be ‘REAL’ with a magnitude that is less than or equal to one. _Return value_: The return value is of the same type and kind as X. The real part of the result is in degrees and lies in the range 0 \leq \Re \acos(x) \leq 180. _Example_: program test_acosd real(8) :: x = 0.866_8 x = acosd(x) end program test_acosd _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ACOSD(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 2023 ‘DACOSD(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Inverse function: *note COSD:: Radians function: *note ACOS::  File: gfortran.info, Node: ACOSH, Next: ADJUSTL, Prev: ACOSD, Up: Intrinsic Procedures 8.8 ‘ACOSH’ -- Inverse hyperbolic cosine function ================================================= _Synopsis_: ‘RESULT = ACOSH(X)’ _Description_: ‘ACOSH(X)’ computes the inverse hyperbolic cosine of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has the same type and kind as X. If X is complex, the imaginary part of the result is in radians and lies between 0 \leq \Im \acosh(x) \leq \pi. _Example_: PROGRAM test_acosh REAL(8), DIMENSION(3) :: x = (/ 1.0, 2.0, 3.0 /) WRITE (*,*) ACOSH(x) END PROGRAM _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DACOSH(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later _See also_: Inverse function: *note COSH::  File: gfortran.info, Node: ADJUSTL, Next: ADJUSTR, Prev: ACOSH, Up: Intrinsic Procedures 8.9 ‘ADJUSTL’ -- Left adjust a string ===================================== _Synopsis_: ‘RESULT = ADJUSTL(STRING)’ _Description_: ‘ADJUSTL(STRING)’ left adjusts a string by removing leading spaces. Spaces are inserted at the end of the string as needed. _Class_: Elemental function _Arguments_: STRING The type shall be ‘CHARACTER’. _Return value_: The return value is of type ‘CHARACTER’ and of the same kind as STRING where leading spaces are removed and the same number of spaces are inserted on the end of STRING. _Example_: program test_adjustl character(len=20) :: str = ' gfortran' str = adjustl(str) print *, str end program test_adjustl _Standard_: Fortran 90 and later _See also_: *note ADJUSTR::, *note TRIM::  File: gfortran.info, Node: ADJUSTR, Next: AIMAG, Prev: ADJUSTL, Up: Intrinsic Procedures 8.10 ‘ADJUSTR’ -- Right adjust a string ======================================= _Synopsis_: ‘RESULT = ADJUSTR(STRING)’ _Description_: ‘ADJUSTR(STRING)’ right adjusts a string by removing trailing spaces. Spaces are inserted at the start of the string as needed. _Class_: Elemental function _Arguments_: STR The type shall be ‘CHARACTER’. _Return value_: The return value is of type ‘CHARACTER’ and of the same kind as STRING where trailing spaces are removed and the same number of spaces are inserted at the start of STRING. _Example_: program test_adjustr character(len=20) :: str = 'gfortran' str = adjustr(str) print *, str end program test_adjustr _Standard_: Fortran 90 and later _See also_: *note ADJUSTL::, *note TRIM::  File: gfortran.info, Node: AIMAG, Next: AINT, Prev: ADJUSTR, Up: Intrinsic Procedures 8.11 ‘AIMAG’ -- Imaginary part of complex number ================================================ _Synopsis_: ‘RESULT = AIMAG(Z)’ _Description_: ‘AIMAG(Z)’ yields the imaginary part of complex argument ‘Z’. The ‘IMAG(Z)’ and ‘IMAGPART(Z)’ intrinsic functions are provided for compatibility with ‘g77’, and their use in new code is strongly discouraged. _Class_: Elemental function _Arguments_: Z The type of the argument shall be ‘COMPLEX’. _Return value_: The return value is of type ‘REAL’ with the kind type parameter of the argument. _Example_: program test_aimag complex(4) z4 complex(8) z8 z4 = cmplx(1.e0_4, 0.e0_4) z8 = cmplx(0.e0_8, 1.e0_8) print *, aimag(z4), dimag(z8) end program test_aimag _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘AIMAG(Z)’ ‘COMPLEX Z’ ‘REAL’ Fortran 77 and later ‘DIMAG(Z)’ ‘COMPLEX(8) Z’ ‘REAL(8)’ GNU extension ‘IMAG(Z)’ ‘COMPLEX Z’ ‘REAL’ GNU extension ‘IMAGPART(Z)’ ‘COMPLEX Z’ ‘REAL’ GNU extension _Standard_: Fortran 77 and later, has overloads that are GNU extensions  File: gfortran.info, Node: AINT, Next: ALARM, Prev: AIMAG, Up: Intrinsic Procedures 8.12 ‘AINT’ -- Truncate to a whole number ========================================= _Synopsis_: ‘RESULT = AINT(A [, KIND])’ _Description_: ‘AINT(A [, KIND])’ truncates its argument to a whole number. _Class_: Elemental function _Arguments_: A The type of the argument shall be ‘REAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘REAL’ with the kind type parameter of the argument if the optional KIND is absent; otherwise, the kind type parameter is given by KIND. If the magnitude of X is less than one, ‘AINT(X)’ returns zero. If the magnitude is equal to or greater than one then it returns the largest whole number that does not exceed its magnitude. The sign is the same as the sign of X. _Example_: program test_aint real(4) x4 real(8) x8 x4 = 1.234E0_4 x8 = 4.321_8 print *, aint(x4), dint(x8) x8 = aint(x4,8) end program test_aint _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘AINT(A)’ ‘REAL(4) A’ ‘REAL(4)’ Fortran 77 and later ‘DINT(A)’ ‘REAL(8) A’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later  File: gfortran.info, Node: ALARM, Next: ALL, Prev: AINT, Up: Intrinsic Procedures 8.13 ‘ALARM’ -- Execute a routine after a given delay ===================================================== _Synopsis_: ‘CALL ALARM(SECONDS, HANDLER [, STATUS])’ _Description_: ‘ALARM(SECONDS, HANDLER [, STATUS])’ causes external subroutine HANDLER to be executed after a delay of SECONDS by using ‘alarm(2)’ to set up a signal and ‘signal(2)’ to catch it. If STATUS is supplied, it is returned with the number of seconds remaining until any previously scheduled alarm was due to be delivered, or zero if there was no previously scheduled alarm. _Class_: Subroutine _Arguments_: SECONDS The type of the argument shall be a scalar ‘INTEGER’. It is ‘INTENT(IN)’. HANDLER Signal handler (‘INTEGER FUNCTION’ or ‘SUBROUTINE’) or dummy/global ‘INTEGER’ scalar. The scalar values may be either ‘SIG_IGN=1’ to ignore the alarm generated or ‘SIG_DFL=0’ to set the default action. It is ‘INTENT(IN)’. STATUS (Optional) STATUS shall be a scalar variable of the default ‘INTEGER’ kind. It is ‘INTENT(OUT)’. _Example_: program test_alarm external handler_print integer i call alarm (3, handler_print, i) print *, i call sleep(10) end program test_alarm This causes the external routine HANDLER_PRINT to be called after 3 seconds. _Standard_: GNU extension  File: gfortran.info, Node: ALL, Next: ALLOCATED, Prev: ALARM, Up: Intrinsic Procedures 8.14 ‘ALL’ -- All values in MASK along DIM are true =================================================== _Synopsis_: ‘RESULT = ALL(MASK [, DIM])’ _Description_: ‘ALL(MASK [, DIM])’ determines if all the values are true in MASK in the array along dimension DIM. _Class_: Transformational function _Arguments_: MASK The type of the argument shall be ‘LOGICAL’ and it shall not be scalar. DIM (Optional) DIM shall be a scalar integer with a value that lies between one and the rank of MASK. _Return value_: ‘ALL(MASK)’ returns a scalar value of type ‘LOGICAL’ where the kind type parameter is the same as the kind type parameter of MASK. If DIM is present, then ‘ALL(MASK, DIM)’ returns an array with the rank of MASK minus 1. The shape is determined from the shape of MASK where the DIM dimension is elided. (A) ‘ALL(MASK)’ is true if all elements of MASK are true. It also is true if MASK has zero size; otherwise, it is false. (B) If the rank of MASK is one, then ‘ALL(MASK,DIM)’ is equivalent to ‘ALL(MASK)’. If the rank is greater than one, then ‘ALL(MASK,DIM)’ is determined by applying ‘ALL’ to the array sections. _Example_: program test_all logical l l = all((/.true., .true., .true./)) print *, l call section contains subroutine section integer a(2,3), b(2,3) a = 1 b = 1 b(2,2) = 2 print *, all(a .eq. b, 1) print *, all(a .eq. b, 2) end subroutine section end program test_all _Standard_: Fortran 90 and later  File: gfortran.info, Node: ALLOCATED, Next: AND, Prev: ALL, Up: Intrinsic Procedures 8.15 ‘ALLOCATED’ -- Status of an allocatable entity =================================================== _Synopsis_: ‘RESULT = ALLOCATED(ARRAY)’ ‘RESULT = ALLOCATED(SCALAR)’ _Description_: ‘ALLOCATED(ARRAY)’ and ‘ALLOCATED(SCALAR)’ check the allocation status of ARRAY and SCALAR, respectively. _Class_: Inquiry function _Arguments_: ARRAY The argument shall be an ‘ALLOCATABLE’ array. SCALAR The argument shall be an ‘ALLOCATABLE’ scalar. _Return value_: The return value is a scalar ‘LOGICAL’ with the default logical kind type parameter. If the argument is allocated, then the result is ‘.TRUE.’; otherwise, it returns ‘.FALSE.’ _Example_: program test_allocated integer :: i = 4 real(4), allocatable :: x(:) if (.not. allocated(x)) allocate(x(i)) end program test_allocated _Standard_: Fortran 90 and later; for the ‘SCALAR=’ keyword and allocatable scalar entities, Fortran 2003 and later.  File: gfortran.info, Node: AND, Next: ANINT, Prev: ALLOCATED, Up: Intrinsic Procedures 8.16 ‘AND’ -- Bitwise logical AND ================================= _Synopsis_: ‘RESULT = AND(I, J)’ _Description_: Bitwise logical ‘AND’. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. For integer arguments, programmers should consider the use of the *note IAND:: intrinsic defined by the Fortran standard. _Class_: Function _Arguments_: I The type shall be either a scalar ‘INTEGER’ type or a scalar ‘LOGICAL’ type or a boz-literal-constant. J The type shall be the same as the type of I or a boz-literal-constant. I and J shall not both be boz-literal-constants. If either I or J is a boz-literal-constant, then the other argument must be a scalar ‘INTEGER’. _Return value_: The return type is either a scalar ‘INTEGER’ or a scalar ‘LOGICAL’. If the kind type parameters differ, then the smaller kind type is implicitly converted to larger kind, and the return has the larger kind. A boz-literal-constant is converted to an ‘INTEGER’ with the kind type parameter of the other argument as-if a call to *note INT:: occurred. _Example_: PROGRAM test_and LOGICAL :: T = .TRUE., F = .FALSE. INTEGER :: a, b DATA a / Z'F' /, b / Z'3' / WRITE (*,*) AND(T, T), AND(T, F), AND(F, T), AND(F, F) WRITE (*,*) AND(a, b) END PROGRAM _Standard_: GNU extension _See also_: Fortran 95 elemental function: *note IAND::  File: gfortran.info, Node: ANINT, Next: ANY, Prev: AND, Up: Intrinsic Procedures 8.17 ‘ANINT’ -- Nearest whole number ==================================== _Synopsis_: ‘RESULT = ANINT(A [, KIND])’ _Description_: ‘ANINT(A [, KIND])’ rounds its argument to the nearest whole number. _Class_: Elemental function _Arguments_: A The type of the argument shall be ‘REAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type real with the kind type parameter of the argument if the optional KIND is absent; otherwise, the kind type parameter is given by KIND. If A is greater than zero, ‘ANINT(A)’ returns ‘AINT(X+0.5)’. If A is less than or equal to zero then it returns ‘AINT(X-0.5)’. _Example_: program test_anint real(4) x4 real(8) x8 x4 = 1.234E0_4 x8 = 4.321_8 print *, anint(x4), dnint(x8) x8 = anint(x4,8) end program test_anint _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ANINT(A)’ ‘REAL(4) A’ ‘REAL(4)’ Fortran 77 and later ‘DNINT(A)’ ‘REAL(8) A’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later  File: gfortran.info, Node: ANY, Next: ASIN, Prev: ANINT, Up: Intrinsic Procedures 8.18 ‘ANY’ -- Any value in MASK along DIM is true ================================================= _Synopsis_: ‘RESULT = ANY(MASK [, DIM])’ _Description_: ‘ANY(MASK [, DIM])’ determines if any of the values in the logical array MASK along dimension DIM are ‘.TRUE.’. _Class_: Transformational function _Arguments_: MASK The type of the argument shall be ‘LOGICAL’ and it shall not be scalar. DIM (Optional) DIM shall be a scalar integer with a value that lies between one and the rank of MASK. _Return value_: ‘ANY(MASK)’ returns a scalar value of type ‘LOGICAL’ where the kind type parameter is the same as the kind type parameter of MASK. If DIM is present, then ‘ANY(MASK, DIM)’ returns an array with the rank of MASK minus 1. The shape is determined from the shape of MASK where the DIM dimension is elided. (A) ‘ANY(MASK)’ is true if any element of MASK is true; otherwise, it is false. It also is false if MASK has zero size. (B) If the rank of MASK is one, then ‘ANY(MASK,DIM)’ is equivalent to ‘ANY(MASK)’. If the rank is greater than one, then ‘ANY(MASK,DIM)’ is determined by applying ‘ANY’ to the array sections. _Example_: program test_any logical l l = any((/.true., .true., .true./)) print *, l call section contains subroutine section integer a(2,3), b(2,3) a = 1 b = 1 b(2,2) = 2 print *, any(a .eq. b, 1) print *, any(a .eq. b, 2) end subroutine section end program test_any _Standard_: Fortran 90 and later  File: gfortran.info, Node: ASIN, Next: ASIND, Prev: ANY, Up: Intrinsic Procedures 8.19 ‘ASIN’ -- Arcsine function =============================== _Synopsis_: ‘RESULT = ASIN(X)’ _Description_: ‘ASIN(X)’ computes the arcsine of its X (inverse of ‘SIN(X)’). _Class_: Elemental function _Arguments_: X The type shall be either ‘REAL’ and a magnitude that is less than or equal to one - or be ‘COMPLEX’. _Return value_: The return value is of the same type and kind as X. The real part of the result is in radians and lies in the range -\pi/2 \leq \Re \asin(x) \leq \pi/2. _Example_: program test_asin real(8) :: x = 0.866_8 x = asin(x) end program test_asin _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ASIN(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DASIN(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, for a complex argument Fortran 2008 or later _See also_: Inverse function: *note SIN:: Degrees function: *note ASIND::  File: gfortran.info, Node: ASIND, Next: ASINH, Prev: ASIN, Up: Intrinsic Procedures 8.20 ‘ASIND’ -- Arcsine function, degrees ========================================= _Synopsis_: ‘RESULT = ASIND(X)’ _Description_: ‘ASIND(X)’ computes the arcsine of its X in degrees (inverse of ‘SIND(X)’). _Class_: Elemental function _Arguments_: X The type shall be either ‘REAL’ and a magnitude that is less than or equal to one. _Return value_: The return value is of the same type and kind as X. The result is in degrees and lies in the range -90 \leq \Re \asin(x) \leq 90. _Example_: program test_asind real(8) :: x = 0.866_8 x = asind(x) end program test_asind _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ASIND(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 2023 ‘DASIND(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Inverse function: *note SIND:: Radians function: *note ASIN::  File: gfortran.info, Node: ASINH, Next: ASSOCIATED, Prev: ASIND, Up: Intrinsic Procedures 8.21 ‘ASINH’ -- Inverse hyperbolic sine function ================================================ _Synopsis_: ‘RESULT = ASINH(X)’ _Description_: ‘ASINH(X)’ computes the inverse hyperbolic sine of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value is of the same type and kind as X. If X is complex, the imaginary part of the result is in radians and lies between -\pi/2 \leq \Im \asinh(x) \leq \pi/2. _Example_: PROGRAM test_asinh REAL(8), DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /) WRITE (*,*) ASINH(x) END PROGRAM _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DASINH(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension. _Standard_: Fortran 2008 and later _See also_: Inverse function: *note SINH::  File: gfortran.info, Node: ASSOCIATED, Next: ATAN, Prev: ASINH, Up: Intrinsic Procedures 8.22 ‘ASSOCIATED’ -- Status of a pointer or pointer/target pair =============================================================== _Synopsis_: ‘RESULT = ASSOCIATED(POINTER [, TARGET])’ _Description_: ‘ASSOCIATED(POINTER [, TARGET])’ determines the status of the pointer POINTER or if POINTER is associated with the target TARGET. _Class_: Inquiry function _Arguments_: POINTER POINTER shall have the ‘POINTER’ attribute and it can be of any type. TARGET (Optional) TARGET shall be a pointer or a target. It must have the same type, kind type parameter, and array rank as POINTER. The association status of neither POINTER nor TARGET shall be undefined. _Return value_: ‘ASSOCIATED(POINTER)’ returns a scalar value of type ‘LOGICAL(4)’. There are several cases: (A) When the optional TARGET is not present then ‘ASSOCIATED(POINTER)’ is true if POINTER is associated with a target; otherwise, it returns false. (B) If TARGET is present and a scalar target, the result is true if TARGET is not a zero-sized storage sequence and the target associated with POINTER occupies the same storage units. If POINTER is disassociated, the result is false. (C) If TARGET is present and an array target, the result is true if TARGET and POINTER have the same shape, are not zero-sized arrays, are arrays whose elements are not zero-sized storage sequences, and TARGET and POINTER occupy the same storage units in array element order. As in case(B), the result is false, if POINTER is disassociated. (D) If TARGET is present and an scalar pointer, the result is true if TARGET is associated with POINTER, the target associated with TARGET are not zero-sized storage sequences and occupy the same storage units. The result is false, if either TARGET or POINTER is disassociated. (E) If TARGET is present and an array pointer, the result is true if target associated with POINTER and the target associated with TARGET have the same shape, are not zero-sized arrays, are arrays whose elements are not zero-sized storage sequences, and TARGET and POINTER occupy the same storage units in array element order. The result is false, if either TARGET or POINTER is disassociated. _Example_: program test_associated implicit none real, target :: tgt(2) = (/1., 2./) real, pointer :: ptr(:) ptr => tgt if (associated(ptr) .eqv. .false.) call abort if (associated(ptr,tgt) .eqv. .false.) call abort end program test_associated _Standard_: Fortran 90 and later _See also_: *note NULL::  File: gfortran.info, Node: ATAN, Next: ATAND, Prev: ASSOCIATED, Up: Intrinsic Procedures 8.23 ‘ATAN’ -- Arctangent function ================================== _Synopsis_: ‘RESULT = ATAN(X)’ ‘RESULT = ATAN(Y, X)’ _Description_: ‘ATAN(X)’ computes the arctangent of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’; if Y is present, X shall be REAL. Y The type and kind type parameter shall be the same as X. _Return value_: The return value is of the same type and kind as X. If Y is present, the result is identical to ‘ATAN2(Y,X)’. Otherwise, it is the arctangent of X, where the real part of the result is in radians and lies in the range -\pi/2 \leq \Re \atan(x) \leq \pi/2. _Example_: program test_atan real(8) :: x = 2.866_8 x = atan(x) end program test_atan _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ATAN(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DATAN(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, for a complex argument and for two arguments Fortran 2008 or later _See also_: Inverse function: *note TAN:: Degrees function: *note ATAND::  File: gfortran.info, Node: ATAND, Next: ATAN2, Prev: ATAN, Up: Intrinsic Procedures 8.24 ‘ATAND’ -- Arctangent function, degrees ============================================ _Synopsis_: ‘RESULT = ATAND(X)’ _Description_: ‘ATAND(X)’ computes the arctangent of X in degrees (inverse of *note TAND::). _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’; if Y is present, X shall be REAL. Y The type and kind type parameter shall be the same as X. _Return value_: The return value is of the same type and kind as X. The result is in degrees and lies in the range -90 \leq \Re \atand(x) \leq 90. _Example_: program test_atand real(8) :: x = 2.866_8 x = atand(x) end program test_atand _Specific names_: Name Argument Return type Standard -------------------------------------------------------------------------- ‘ATAND(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 2023 ‘DATAND(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Inverse function: *note TAND:: Radians function: *note ATAN::  File: gfortran.info, Node: ATAN2, Next: ATAN2D, Prev: ATAND, Up: Intrinsic Procedures 8.25 ‘ATAN2’ -- Arctangent function =================================== _Synopsis_: ‘RESULT = ATAN2(Y, X)’ _Description_: ‘ATAN2(Y, X)’ computes the principal value of the argument function of the complex number X + i Y. This function can be used to transform from Cartesian into polar coordinates and allows to determine the angle in the correct quadrant. _Class_: Elemental function _Arguments_: Y The type shall be ‘REAL’. X The type and kind type parameter shall be the same as Y. If Y is zero, then X must be nonzero. _Return value_: The return value has the same type and kind type parameter as Y. It is the principal value of the complex number X + i Y. If X is nonzero, then it lies in the range -\pi \le \atan (x) \leq \pi. The sign is positive if Y is positive. If Y is zero, then the return value is zero if X is strictly positive, \pi if X is negative and Y is positive zero (or the processor does not handle signed zeros), and -\pi if X is negative and Y is negative zero. Finally, if X is zero, then the magnitude of the result is \pi/2. _Example_: program test_atan2 real(4) :: x = 1.e0_4, y = 0.5e0_4 x = atan2(y,x) end program test_atan2 _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ATAN2(X, Y)’ ‘REAL(4) X, Y’ ‘REAL(4)’ Fortran 77 and later ‘DATAN2(X, Y)’ ‘REAL(8) X, Y’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later _See also_: Alias: *note ATAN:: Degrees function: *note ATAN2D::  File: gfortran.info, Node: ATAN2D, Next: ATANH, Prev: ATAN2, Up: Intrinsic Procedures 8.26 ‘ATAN2D’ -- Arctangent function, degrees ============================================= _Synopsis_: ‘RESULT = ATAN2D(Y, X)’ _Description_: ‘ATAN2D(Y, X)’ computes the principal value of the argument function of the complex number X + i Y in degrees. This function can be used to transform from Cartesian into polar coordinates and allows to determine the angle in the correct quadrant. _Class_: Elemental function _Arguments_: Y The type shall be ‘REAL’. X The type and kind type parameter shall be the same as Y. If Y is zero, then X must be nonzero. _Return value_: The return value has the same type and kind type parameter as Y. It is the principal value of the complex number X + i Y. If X is nonzero, then it lies in the range -180 \le \atan (x) \leq 180. The sign is positive if Y is positive. If Y is zero, then the return value is zero if X is strictly positive, 180 if X is negative and Y is positive zero (or the processor does not handle signed zeros), and -180 if X is negative and Y is negative zero. Finally, if X is zero, then the magnitude of the result is 90. _Example_: program test_atan2d real(4) :: x = 1.e0_4, y = 0.5e0_4 x = atan2d(y,x) end program test_atan2d _Specific names_: Name Argument Return type Standard -------------------------------------------------------------------------- ‘ATAN2D(X, Y)’ ‘REAL(4) X, Y’ ‘REAL(4)’ Fortran 2023 ‘DATAN2D(X, Y)’ ‘REAL(8) X, Y’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Alias: *note ATAND:: Radians function: *note ATAN2::  File: gfortran.info, Node: ATANH, Next: ATOMIC_ADD, Prev: ATAN2D, Up: Intrinsic Procedures 8.27 ‘ATANH’ -- Inverse hyperbolic tangent function =================================================== _Synopsis_: ‘RESULT = ATANH(X)’ _Description_: ‘ATANH(X)’ computes the inverse hyperbolic tangent of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X. If X is complex, the imaginary part of the result is in radians and lies between -\pi/2 \leq \Im \atanh(x) \leq \pi/2. _Example_: PROGRAM test_atanh REAL, DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /) WRITE (*,*) ATANH(x) END PROGRAM _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DATANH(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later _See also_: Inverse function: *note TANH::  File: gfortran.info, Node: ATOMIC_ADD, Next: ATOMIC_AND, Prev: ATANH, Up: Intrinsic Procedures 8.28 ‘ATOMIC_ADD’ -- Atomic ADD operation ========================================= _Synopsis_: ‘CALL ATOMIC_ADD (ATOM, VALUE [, STAT])’ _Description_: ‘ATOMIC_ADD(ATOM, VALUE)’ atomically adds the value of VALUE to the variable ATOM. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*] call atomic_add (atom[1], this_image()) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_FETCH_ADD::, *note ISO_FORTRAN_ENV::, *note ATOMIC_AND::, *note ATOMIC_OR::, *note ATOMIC_XOR::  File: gfortran.info, Node: ATOMIC_AND, Next: ATOMIC_CAS, Prev: ATOMIC_ADD, Up: Intrinsic Procedures 8.29 ‘ATOMIC_AND’ -- Atomic bitwise AND operation ================================================= _Synopsis_: ‘CALL ATOMIC_AND (ATOM, VALUE [, STAT])’ _Description_: ‘ATOMIC_AND(ATOM, VALUE)’ atomically defines ATOM with the bitwise AND between the values of ATOM and VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*] call atomic_and (atom[1], int(b'10100011101')) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_FETCH_AND::, *note ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_OR::, *note ATOMIC_XOR::  File: gfortran.info, Node: ATOMIC_CAS, Next: ATOMIC_DEFINE, Prev: ATOMIC_AND, Up: Intrinsic Procedures 8.30 ‘ATOMIC_CAS’ -- Atomic compare and swap ============================================ _Synopsis_: ‘CALL ATOMIC_CAS (ATOM, OLD, COMPARE, NEW [, STAT])’ _Description_: ‘ATOMIC_CAS’ compares the variable ATOM with the value of COMPARE; if the value is the same, ATOM is set to the value of NEW. Additionally, OLD is set to the value of ATOM that was used for the comparison. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of either integer type with ‘ATOMIC_INT_KIND’ kind or logical type with ‘ATOMIC_LOGICAL_KIND’ kind. OLD Scalar of the same type and kind as ATOM. COMPARE Scalar variable of the same type and kind as ATOM. NEW Scalar variable of the same type as ATOM. If kind is different, the value is converted to the kind of ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env logical(atomic_logical_kind) :: atom[*], prev call atomic_cas (atom[1], prev, .false., .true.)) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_REF::, *note ISO_FORTRAN_ENV::  File: gfortran.info, Node: ATOMIC_DEFINE, Next: ATOMIC_FETCH_ADD, Prev: ATOMIC_CAS, Up: Intrinsic Procedures 8.31 ‘ATOMIC_DEFINE’ -- Setting a variable atomically ===================================================== _Synopsis_: ‘CALL ATOMIC_DEFINE (ATOM, VALUE [, STAT])’ _Description_: ‘ATOMIC_DEFINE(ATOM, VALUE)’ defines the variable ATOM with the value VALUE atomically. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of either integer type with ‘ATOMIC_INT_KIND’ kind or logical type with ‘ATOMIC_LOGICAL_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*] call atomic_define (atom[1], this_image()) end program atomic _Standard_: Fortran 2008 and later; with STAT, TS 18508 or later _See also_: *note ATOMIC_REF::, *note ATOMIC_CAS::, *note ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_AND::, *note ATOMIC_OR::, *note ATOMIC_XOR::  File: gfortran.info, Node: ATOMIC_FETCH_ADD, Next: ATOMIC_FETCH_AND, Prev: ATOMIC_DEFINE, Up: Intrinsic Procedures 8.32 ‘ATOMIC_FETCH_ADD’ -- Atomic ADD operation with prior fetch ================================================================ _Synopsis_: ‘CALL ATOMIC_FETCH_ADD (ATOM, VALUE, OLD [, STAT])’ _Description_: ‘ATOMIC_FETCH_ADD(ATOM, VALUE, OLD)’ atomically stores the value of ATOM in OLD and adds the value of VALUE to the variable ATOM. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. ‘ATOMIC_LOGICAL_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. OLD Scalar of the same type and kind as ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*], old call atomic_add (atom[1], this_image(), old) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_ADD::, *note ISO_FORTRAN_ENV::, *note ATOMIC_FETCH_AND::, *note ATOMIC_FETCH_OR::, *note ATOMIC_FETCH_XOR::  File: gfortran.info, Node: ATOMIC_FETCH_AND, Next: ATOMIC_FETCH_OR, Prev: ATOMIC_FETCH_ADD, Up: Intrinsic Procedures 8.33 ‘ATOMIC_FETCH_AND’ -- Atomic bitwise AND operation with prior fetch ======================================================================== _Synopsis_: ‘CALL ATOMIC_FETCH_AND (ATOM, VALUE, OLD [, STAT])’ _Description_: ‘ATOMIC_AND(ATOM, VALUE)’ atomically stores the value of ATOM in OLD and defines ATOM with the bitwise AND between the values of ATOM and VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. OLD Scalar of the same type and kind as ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*], old call atomic_fetch_and (atom[1], int(b'10100011101'), old) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_AND::, *note ISO_FORTRAN_ENV::, *note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_OR::, *note ATOMIC_FETCH_XOR::  File: gfortran.info, Node: ATOMIC_FETCH_OR, Next: ATOMIC_FETCH_XOR, Prev: ATOMIC_FETCH_AND, Up: Intrinsic Procedures 8.34 ‘ATOMIC_FETCH_OR’ -- Atomic bitwise OR operation with prior fetch ====================================================================== _Synopsis_: ‘CALL ATOMIC_FETCH_OR (ATOM, VALUE, OLD [, STAT])’ _Description_: ‘ATOMIC_OR(ATOM, VALUE)’ atomically stores the value of ATOM in OLD and defines ATOM with the bitwise OR between the values of ATOM and VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. OLD Scalar of the same type and kind as ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*], old call atomic_fetch_or (atom[1], int(b'10100011101'), old) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_OR::, *note ISO_FORTRAN_ENV::, *note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_AND::, *note ATOMIC_FETCH_XOR::  File: gfortran.info, Node: ATOMIC_FETCH_XOR, Next: ATOMIC_OR, Prev: ATOMIC_FETCH_OR, Up: Intrinsic Procedures 8.35 ‘ATOMIC_FETCH_XOR’ -- Atomic bitwise XOR operation with prior fetch ======================================================================== _Synopsis_: ‘CALL ATOMIC_FETCH_XOR (ATOM, VALUE, OLD [, STAT])’ _Description_: ‘ATOMIC_XOR(ATOM, VALUE)’ atomically stores the value of ATOM in OLD and defines ATOM with the bitwise XOR between the values of ATOM and VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. OLD Scalar of the same type and kind as ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*], old call atomic_fetch_xor (atom[1], int(b'10100011101'), old) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_XOR::, *note ISO_FORTRAN_ENV::, *note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_AND::, *note ATOMIC_FETCH_OR::  File: gfortran.info, Node: ATOMIC_OR, Next: ATOMIC_REF, Prev: ATOMIC_FETCH_XOR, Up: Intrinsic Procedures 8.36 ‘ATOMIC_OR’ -- Atomic bitwise OR operation =============================================== _Synopsis_: ‘CALL ATOMIC_OR (ATOM, VALUE [, STAT])’ _Description_: ‘ATOMIC_OR(ATOM, VALUE)’ atomically defines ATOM with the bitwise AND between the values of ATOM and VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*] call atomic_or (atom[1], int(b'10100011101')) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_FETCH_OR::, *note ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_OR::, *note ATOMIC_XOR::  File: gfortran.info, Node: ATOMIC_REF, Next: ATOMIC_XOR, Prev: ATOMIC_OR, Up: Intrinsic Procedures 8.37 ‘ATOMIC_REF’ -- Obtaining the value of a variable atomically ================================================================= _Synopsis_: ‘CALL ATOMIC_REF(VALUE, ATOM [, STAT])’ _Description_: ‘ATOMIC_DEFINE(ATOM, VALUE)’ atomically assigns the value of the variable ATOM to VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. ATOM Scalar coarray or coindexed variable of either integer type with ‘ATOMIC_INT_KIND’ kind or logical type with ‘ATOMIC_LOGICAL_KIND’ kind. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env logical(atomic_logical_kind) :: atom[*] logical :: val call atomic_ref (atom, .false.) ! ... call atomic_ref (atom, val) if (val) then print *, "Obtained" end if end program atomic _Standard_: Fortran 2008 and later; with STAT, TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_CAS::, *note ISO_FORTRAN_ENV::, *note ATOMIC_FETCH_ADD::, *note ATOMIC_FETCH_AND::, *note ATOMIC_FETCH_OR::, *note ATOMIC_FETCH_XOR::  File: gfortran.info, Node: ATOMIC_XOR, Next: BACKTRACE, Prev: ATOMIC_REF, Up: Intrinsic Procedures 8.38 ‘ATOMIC_XOR’ -- Atomic bitwise OR operation ================================================ _Synopsis_: ‘CALL ATOMIC_XOR (ATOM, VALUE [, STAT])’ _Description_: ‘ATOMIC_AND(ATOM, VALUE)’ atomically defines ATOM with the bitwise XOR between the values of ATOM and VALUE. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of ‘ISO_FORTRAN_ENV’'s ‘STAT_STOPPED_IMAGE’ and if the remote image has failed, the value ‘STAT_FAILED_IMAGE’. _Class_: Atomic subroutine _Arguments_: ATOM Scalar coarray or coindexed variable of integer type with ‘ATOMIC_INT_KIND’ kind. VALUE Scalar of the same type as ATOM. If the kind is different, the value is converted to the kind of ATOM. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env integer(atomic_int_kind) :: atom[*] call atomic_xor (atom[1], int(b'10100011101')) end program atomic _Standard_: TS 18508 or later _See also_: *note ATOMIC_DEFINE::, *note ATOMIC_FETCH_XOR::, *note ISO_FORTRAN_ENV::, *note ATOMIC_ADD::, *note ATOMIC_OR::, *note ATOMIC_XOR::  File: gfortran.info, Node: BACKTRACE, Next: BESSEL_J0, Prev: ATOMIC_XOR, Up: Intrinsic Procedures 8.39 ‘BACKTRACE’ -- Show a backtrace ==================================== _Synopsis_: ‘CALL BACKTRACE’ _Description_: ‘BACKTRACE’ shows a backtrace at an arbitrary place in user code. Program execution continues normally afterwards. The backtrace information is printed to the unit corresponding to ‘ERROR_UNIT’ in ‘ISO_FORTRAN_ENV’. _Class_: Subroutine _Arguments_: None _Standard_: GNU extension _See also_: *note ABORT::  File: gfortran.info, Node: BESSEL_J0, Next: BESSEL_J1, Prev: BACKTRACE, Up: Intrinsic Procedures 8.40 ‘BESSEL_J0’ -- Bessel function of the first kind of order 0 ================================================================ _Synopsis_: ‘RESULT = BESSEL_J0(X)’ _Description_: ‘BESSEL_J0(X)’ computes the Bessel function of the first kind of order 0 of X. This function is available under the name ‘BESJ0’ as a GNU extension. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’ and lies in the range - 0.4027... \leq Bessel (0,x) \leq 1. It has the same kind as X. _Example_: program test_besj0 real(8) :: x = 0.0_8 x = bessel_j0(x) end program test_besj0 _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DBESJ0(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later  File: gfortran.info, Node: BESSEL_J1, Next: BESSEL_JN, Prev: BESSEL_J0, Up: Intrinsic Procedures 8.41 ‘BESSEL_J1’ -- Bessel function of the first kind of order 1 ================================================================ _Synopsis_: ‘RESULT = BESSEL_J1(X)’ _Description_: ‘BESSEL_J1(X)’ computes the Bessel function of the first kind of order 1 of X. This function is available under the name ‘BESJ1’ as a GNU extension. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’ and lies in the range - 0.5818... \leq Bessel (0,x) \leq 0.5818 . It has the same kind as X. _Example_: program test_besj1 real(8) :: x = 1.0_8 x = bessel_j1(x) end program test_besj1 _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DBESJ1(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008  File: gfortran.info, Node: BESSEL_JN, Next: BESSEL_Y0, Prev: BESSEL_J1, Up: Intrinsic Procedures 8.42 ‘BESSEL_JN’ -- Bessel function of the first kind ===================================================== _Synopsis_: ‘RESULT = BESSEL_JN(N, X)’ ‘RESULT = BESSEL_JN(N1, N2, X)’ _Description_: ‘BESSEL_JN(N, X)’ computes the Bessel function of the first kind of order N of X. This function is available under the name ‘BESJN’ as a GNU extension. If N and X are arrays, their ranks and shapes shall conform. ‘BESSEL_JN(N1, N2, X)’ returns an array with the Bessel functions of the first kind of the orders N1 to N2. _Class_: Elemental function, except for the transformational function ‘BESSEL_JN(N1, N2, X)’ _Arguments_: N Shall be a scalar or an array of type ‘INTEGER’. N1 Shall be a non-negative scalar of type ‘INTEGER’. N2 Shall be a non-negative scalar of type ‘INTEGER’. X Shall be a scalar or an array of type ‘REAL’; for ‘BESSEL_JN(N1, N2, X)’ it shall be scalar. _Return value_: The return value is a scalar of type ‘REAL’. It has the same kind as X. _Notes_: The transformational function uses a recurrence algorithm which might, for some values of X, lead to different results than calls to the elemental function. _Example_: program test_besjn real(8) :: x = 1.0_8 x = bessel_jn(5,x) end program test_besjn _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DBESJN(N, X)’ ‘INTEGER N’ ‘REAL(8)’ GNU extension ‘REAL(8) X’ _Standard_: Fortran 2008 and later, negative N is allowed as GNU extension  File: gfortran.info, Node: BESSEL_Y0, Next: BESSEL_Y1, Prev: BESSEL_JN, Up: Intrinsic Procedures 8.43 ‘BESSEL_Y0’ -- Bessel function of the second kind of order 0 ================================================================= _Synopsis_: ‘RESULT = BESSEL_Y0(X)’ _Description_: ‘BESSEL_Y0(X)’ computes the Bessel function of the second kind of order 0 of X. This function is available under the name ‘BESY0’ as a GNU extension. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’. It has the same kind as X. _Example_: program test_besy0 real(8) :: x = 0.0_8 x = bessel_y0(x) end program test_besy0 _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DBESY0(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later  File: gfortran.info, Node: BESSEL_Y1, Next: BESSEL_YN, Prev: BESSEL_Y0, Up: Intrinsic Procedures 8.44 ‘BESSEL_Y1’ -- Bessel function of the second kind of order 1 ================================================================= _Synopsis_: ‘RESULT = BESSEL_Y1(X)’ _Description_: ‘BESSEL_Y1(X)’ computes the Bessel function of the second kind of order 1 of X. This function is available under the name ‘BESY1’ as a GNU extension. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’. It has the same kind as X. _Example_: program test_besy1 real(8) :: x = 1.0_8 x = bessel_y1(x) end program test_besy1 _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DBESY1(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later  File: gfortran.info, Node: BESSEL_YN, Next: BGE, Prev: BESSEL_Y1, Up: Intrinsic Procedures 8.45 ‘BESSEL_YN’ -- Bessel function of the second kind ====================================================== _Synopsis_: ‘RESULT = BESSEL_YN(N, X)’ ‘RESULT = BESSEL_YN(N1, N2, X)’ _Description_: ‘BESSEL_YN(N, X)’ computes the Bessel function of the second kind of order N of X. This function is available under the name ‘BESYN’ as a GNU extension. If N and X are arrays, their ranks and shapes shall conform. ‘BESSEL_YN(N1, N2, X)’ returns an array with the Bessel functions of the first kind of the orders N1 to N2. _Class_: Elemental function, except for the transformational function ‘BESSEL_YN(N1, N2, X)’ _Arguments_: N Shall be a scalar or an array of type ‘INTEGER’ . N1 Shall be a non-negative scalar of type ‘INTEGER’. N2 Shall be a non-negative scalar of type ‘INTEGER’. X Shall be a scalar or an array of type ‘REAL’; for ‘BESSEL_YN(N1, N2, X)’ it shall be scalar. _Return value_: The return value is a scalar of type ‘REAL’. It has the same kind as X. _Notes_: The transformational function uses a recurrence algorithm which might, for some values of X, lead to different results than calls to the elemental function. _Example_: program test_besyn real(8) :: x = 1.0_8 x = bessel_yn(5,x) end program test_besyn _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DBESYN(N,X)’ ‘INTEGER N’ ‘REAL(8)’ GNU extension ‘REAL(8) X’ _Standard_: Fortran 2008 and later, negative N is allowed as GNU extension  File: gfortran.info, Node: BGE, Next: BGT, Prev: BESSEL_YN, Up: Intrinsic Procedures 8.46 ‘BGE’ -- Bitwise greater than or equal to ============================================== _Synopsis_: ‘RESULT = BGE(I, J)’ _Description_: Determines whether an integral is a bitwise greater than or equal to another. _Class_: Elemental function _Arguments_: I Shall be of ‘INTEGER’ or ‘UNSIGNED’ type. J Shall be of the same type and kind as I. _Return value_: The return value is of type ‘LOGICAL’ and of the default kind. _Notes_: For ‘UNSIGNED’ arguments, this function is identical to the ‘.GE.’ and ‘>=’ operators. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note BGT::, *note BLE::, *note BLT::  File: gfortran.info, Node: BGT, Next: BIT_SIZE, Prev: BGE, Up: Intrinsic Procedures 8.47 ‘BGT’ -- Bitwise greater than ================================== _Synopsis_: ‘RESULT = BGT(I, J)’ _Description_: Determines whether an integral is a bitwise greater than another. _Class_: Elemental function _Arguments_: I Shall be of ‘INTEGER’ or ‘UNSIGNED’ type. J Shall be of the same type and kind as I. _Return value_: The return value is of type ‘LOGICAL’ and of the default kind. _Notes_: For ‘UNSIGNED’ arguments, this function is identical to the ‘.GT.’ and ‘>’ operators. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note BGE::, *note BLE::, *note BLT::  File: gfortran.info, Node: BIT_SIZE, Next: BLE, Prev: BGT, Up: Intrinsic Procedures 8.48 ‘BIT_SIZE’ -- Bit size inquiry function ============================================ _Synopsis_: ‘RESULT = BIT_SIZE(I)’ _Description_: ‘BIT_SIZE(I)’ returns the number of bits (for integers, the precision plus the sign bit) represented by the type of I. The result of ‘BIT_SIZE(I)’ is independent of the actual value of I. _Class_: Inquiry function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. _Return value_: The return value is of type ‘INTEGER’ _Example_: program test_bit_size integer :: i = 123 integer :: size size = bit_size(i) print *, size end program test_bit_size _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: BLE, Next: BLT, Prev: BIT_SIZE, Up: Intrinsic Procedures 8.49 ‘BLE’ -- Bitwise less than or equal to =========================================== _Synopsis_: ‘RESULT = BLE(I, J)’ _Description_: Determines whether an integral is a bitwise less than or equal to another. _Class_: Elemental function _Arguments_: I Shall be of ‘INTEGER’ or ‘UNSIGNED’ type. J Shall be of the same type and kind as I. _Return value_: The return value is of type ‘LOGICAL’ and of the default kind. _Notes_: For ‘UNSIGNED’ arguments, this function is identical to the ‘.LE.’ and ‘<=’ operators. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note BGT::, *note BGE::, *note BLT::  File: gfortran.info, Node: BLT, Next: BTEST, Prev: BLE, Up: Intrinsic Procedures 8.50 ‘BLT’ -- Bitwise less than =============================== _Synopsis_: ‘RESULT = BLT(I, J)’ _Description_: Determines whether an integral is a bitwise less than another. _Class_: Elemental function _Arguments_: I Shall be of ‘INTEGER’ or ‘UNSIGNED’ type. J Shall be of the same type and kind as I. _Return value_: The return value is of type ‘LOGICAL’ and of the default kind. _Notes_: For ‘UNSIGNED’ arguments, this function is identical to the ‘.LT.’ and ‘<’ operators. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note BGE::, *note BGT::, *note BLE::  File: gfortran.info, Node: BTEST, Next: C_ASSOCIATED, Prev: BLT, Up: Intrinsic Procedures 8.51 ‘BTEST’ -- Bit test function ================================= _Synopsis_: ‘RESULT = BTEST(I, POS)’ _Description_: ‘BTEST(I,POS)’ returns logical ‘.TRUE.’ if the bit at POS in I is set. The counting of the bits starts at 0. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. POS The type shall be ‘INTEGER’. _Return value_: The return value is of type ‘LOGICAL’ _Example_: program test_btest integer :: i = 32768 + 1024 + 64 integer :: pos logical :: bool do pos=0,16 bool = btest(i, pos) print *, pos, bool end do end program test_btest _Specific names_: Name Argument Return type Standard -------------------------------------------------------------------------- ‘BTEST(I,POS)’ ‘INTEGER I,POS’ ‘LOGICAL’ Fortran 95 and later ‘BBTEST(I,POS)’ ‘INTEGER(1) I,POS’ ‘LOGICAL(1)’ GNU extension ‘BITEST(I,POS)’ ‘INTEGER(2) I,POS’ ‘LOGICAL(2)’ GNU extension ‘BJTEST(I,POS)’ ‘INTEGER(4) I,POS’ ‘LOGICAL(4)’ GNU extension ‘BKTEST(I,POS)’ ‘INTEGER(8) I,POS’ ‘LOGICAL(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions; extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: C_ASSOCIATED, Next: C_F_POINTER, Prev: BTEST, Up: Intrinsic Procedures 8.52 ‘C_ASSOCIATED’ -- Status of a C pointer ============================================ _Synopsis_: ‘RESULT = C_ASSOCIATED(CPTR1[, CPTR2])’ _Description_: ‘C_ASSOCIATED(CPTR1[, CPTR2])’ determines the status of the C pointer CPTR1 or if CPTR1 is associated with the target CPTR2. _Class_: Inquiry function _Arguments_: CPTR1 Scalar of the type ‘C_PTR’ or ‘C_FUNPTR’. CPTR2 (Optional) Scalar of the same type as CPTR1. _Return value_: The return value is of type ‘LOGICAL’; it is ‘.false.’ if either CPTR1 is a C NULL pointer or if CPTR1 and CPTR2 point to different addresses. _Example_: subroutine association_test(a,b) use iso_c_binding, only: c_associated, c_loc, c_ptr implicit none real, pointer :: a type(c_ptr) :: b if(c_associated(b, c_loc(a))) & stop 'b and a do not point to same target' end subroutine association_test _Standard_: Fortran 2003 and later _See also_: *note C_LOC::, *note C_FUNLOC::  File: gfortran.info, Node: C_F_POINTER, Next: C_F_PROCPOINTER, Prev: C_ASSOCIATED, Up: Intrinsic Procedures 8.53 ‘C_F_POINTER’ -- Convert C into Fortran pointer ==================================================== _Synopsis_: ‘CALL C_F_POINTER(CPTR, FPTR[, SHAPE])’ _Description_: ‘C_F_POINTER(CPTR, FPTR[, SHAPE])’ assigns the target of the C pointer CPTR to the Fortran pointer FPTR and specifies its shape. _Class_: Subroutine _Arguments_: CPTR scalar of the type ‘C_PTR’. It is ‘INTENT(IN)’. FPTR pointer interoperable with CPTR. It is ‘INTENT(OUT)’. SHAPE (Optional) Rank-one array of type ‘INTEGER’ with ‘INTENT(IN)’. It shall be present if and only if FPTR is an array. The size must be equal to the rank of FPTR. _Example_: program main use iso_c_binding implicit none interface subroutine my_routine(p) bind(c,name='myC_func') import :: c_ptr type(c_ptr), intent(out) :: p end subroutine end interface type(c_ptr) :: cptr real,pointer :: a(:) call my_routine(cptr) call c_f_pointer(cptr, a, [12]) end program main _Standard_: Fortran 2003 and later _See also_: *note C_LOC::, *note C_F_PROCPOINTER::  File: gfortran.info, Node: C_F_PROCPOINTER, Next: C_FUNLOC, Prev: C_F_POINTER, Up: Intrinsic Procedures 8.54 ‘C_F_PROCPOINTER’ -- Convert C into Fortran procedure pointer ================================================================== _Synopsis_: ‘CALL C_F_PROCPOINTER(CPTR, FPTR)’ _Description_: ‘C_F_PROCPOINTER(CPTR, FPTR)’ Assign the target of the C function pointer CPTR to the Fortran procedure pointer FPTR. _Class_: Subroutine _Arguments_: CPTR scalar of the type ‘C_FUNPTR’. It is ‘INTENT(IN)’. FPTR procedure pointer interoperable with CPTR. It is ‘INTENT(OUT)’. _Example_: program main use iso_c_binding implicit none abstract interface function func(a) import :: c_float real(c_float), intent(in) :: a real(c_float) :: func end function end interface interface function getIterFunc() bind(c,name="getIterFunc") import :: c_funptr type(c_funptr) :: getIterFunc end function end interface type(c_funptr) :: cfunptr procedure(func), pointer :: myFunc cfunptr = getIterFunc() call c_f_procpointer(cfunptr, myFunc) end program main _Standard_: Fortran 2003 and later _See also_: *note C_LOC::, *note C_F_POINTER::  File: gfortran.info, Node: C_FUNLOC, Next: C_LOC, Prev: C_F_PROCPOINTER, Up: Intrinsic Procedures 8.55 ‘C_FUNLOC’ -- Obtain the C address of a procedure ====================================================== _Synopsis_: ‘RESULT = C_FUNLOC(X)’ _Description_: ‘C_FUNLOC(X)’ determines the C address of the argument. _Class_: Inquiry function _Arguments_: X Interoperable function or pointer to such function. _Return value_: The return value is of type ‘C_FUNPTR’ and contains the C address of the argument. _Example_: module x use iso_c_binding implicit none contains subroutine sub(a) bind(c) real(c_float) :: a a = sqrt(a)+5.0 end subroutine sub end module x program main use iso_c_binding use x implicit none interface subroutine my_routine(p) bind(c,name='myC_func') import :: c_funptr type(c_funptr), intent(in) :: p end subroutine end interface call my_routine(c_funloc(sub)) end program main _Standard_: Fortran 2003 and later _See also_: *note C_ASSOCIATED::, *note C_LOC::, *note C_F_POINTER::, *note C_F_PROCPOINTER::  File: gfortran.info, Node: C_LOC, Next: C_SIZEOF, Prev: C_FUNLOC, Up: Intrinsic Procedures 8.56 ‘C_LOC’ -- Obtain the C address of an object ================================================= _Synopsis_: ‘RESULT = C_LOC(X)’ _Description_: ‘C_LOC(X)’ determines the C address of the argument. _Class_: Inquiry function _Arguments_: X Shall have either the POINTER or TARGET attribute. It shall not be a coindexed object. It shall either be a variable with interoperable type and kind type parameters, or be a scalar, nonpolymorphic variable with no length type parameters. _Return value_: The return value is of type ‘C_PTR’ and contains the C address of the argument. _Example_: subroutine association_test(a,b) use iso_c_binding, only: c_associated, c_loc, c_ptr implicit none real, pointer :: a type(c_ptr) :: b if(c_associated(b, c_loc(a))) & stop 'b and a do not point to same target' end subroutine association_test _Standard_: Fortran 2003 and later _See also_: *note C_ASSOCIATED::, *note C_FUNLOC::, *note C_F_POINTER::, *note C_F_PROCPOINTER::  File: gfortran.info, Node: C_SIZEOF, Next: CEILING, Prev: C_LOC, Up: Intrinsic Procedures 8.57 ‘C_SIZEOF’ -- Size in bytes of an expression ================================================= _Synopsis_: ‘N = C_SIZEOF(X)’ _Description_: ‘C_SIZEOF(X)’ calculates the number of bytes of storage the expression ‘X’ occupies. _Class_: Inquiry function of the module ‘ISO_C_BINDING’ _Arguments_: X The argument shall be an interoperable data entity. _Return value_: The return value is of type integer and of the system-dependent kind ‘C_SIZE_T’ (from the ‘ISO_C_BINDING’ module). Its value is the number of bytes occupied by the argument. If the argument has the ‘POINTER’ attribute, the number of bytes of the storage area pointed to is returned. If the argument is of a derived type with ‘POINTER’ or ‘ALLOCATABLE’ components, the return value does not account for the sizes of the data pointed to by these components. _Example_: use iso_c_binding integer(c_int) :: i real(c_float) :: r, s(5) print *, (c_sizeof(s)/c_sizeof(r) == 5) end The example prints ‘T’ unless you are using a platform where default ‘REAL’ variables are unusually padded. _Standard_: Fortran 2008 _See also_: *note SIZEOF::, *note STORAGE_SIZE::  File: gfortran.info, Node: CEILING, Next: CHAR, Prev: C_SIZEOF, Up: Intrinsic Procedures 8.58 ‘CEILING’ -- Integer ceiling function ========================================== _Synopsis_: ‘RESULT = CEILING(A [, KIND])’ _Description_: ‘CEILING(A)’ returns the least integer greater than or equal to A. _Class_: Elemental function _Arguments_: A The type shall be ‘REAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER(KIND)’ if KIND is present and a default-kind ‘INTEGER’ otherwise. _Example_: program test_ceiling real :: x = 63.29 real :: y = -63.59 print *, ceiling(x) ! returns 64 print *, ceiling(y) ! returns -63 end program test_ceiling _Standard_: Fortran 95 and later _See also_: *note FLOOR::, *note NINT::  File: gfortran.info, Node: CHAR, Next: CHDIR, Prev: CEILING, Up: Intrinsic Procedures 8.59 ‘CHAR’ -- Character conversion function ============================================ _Synopsis_: ‘RESULT = CHAR(I [, KIND])’ _Description_: ‘CHAR(I [, KIND])’ returns the character represented by the integer I. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘CHARACTER(1)’ _Example_: program test_char integer :: i = 74 character(1) :: c c = char(i) print *, i, c ! returns 'J' end program test_char _Specific names_: Name Argument Return type Standard -------------------------------------------------------------------------- ‘CHAR(I)’ ‘INTEGER I’ ‘CHARACTER(LEN=1)’ Fortran 77 and later _Notes_: See *note ICHAR:: for a discussion of converting between numerical values and formatted string representations. _Standard_: Fortran 77 and later _See also_: *note ACHAR::, *note IACHAR::, *note ICHAR::  File: gfortran.info, Node: CHDIR, Next: CHMOD, Prev: CHAR, Up: Intrinsic Procedures 8.60 ‘CHDIR’ -- Change working directory ======================================== _Synopsis_: ‘CALL CHDIR(NAME [, STATUS])’ ‘STATUS = CHDIR(NAME)’ _Description_: Change current working directory to a specified path. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: NAME The type shall be ‘CHARACTER’ of default kind and shall specify a valid path within the file system. STATUS (Optional) ‘INTEGER’ status flag of the default kind. Returns 0 on success, and a system specific and nonzero error code otherwise. _Example_: PROGRAM test_chdir CHARACTER(len=255) :: path CALL getcwd(path) WRITE(*,*) TRIM(path) CALL chdir("/tmp") CALL getcwd(path) WRITE(*,*) TRIM(path) END PROGRAM _Standard_: GNU extension _See also_: *note GETCWD::  File: gfortran.info, Node: CHMOD, Next: CMPLX, Prev: CHDIR, Up: Intrinsic Procedures 8.61 ‘CHMOD’ -- Change access permissions of files ================================================== _Synopsis_: ‘CALL CHMOD(NAME, MODE[, STATUS])’ ‘STATUS = CHMOD(NAME, MODE)’ _Description_: ‘CHMOD’ changes the permissions of a file. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: NAME Scalar ‘CHARACTER’ of default kind with the file name. Trailing blanks are ignored unless the character ‘achar(0)’ is present, then all characters up to and excluding ‘achar(0)’ are used as the file name. MODE Scalar ‘CHARACTER’ of default kind giving the file permission. MODE uses the same syntax as the ‘chmod’ utility as defined by the POSIX standard. The argument shall either be a string of a nonnegative octal number or a symbolic mode. STATUS (optional) scalar ‘INTEGER’, which is ‘0’ on success and nonzero otherwise. _Return value_: In either syntax, STATUS is set to ‘0’ on success and nonzero otherwise. _Example_: ‘CHMOD’ as subroutine program chmod_test implicit none integer :: status call chmod('test.dat','u+x',status) print *, 'Status: ', status end program chmod_test ‘CHMOD’ as function: program chmod_test implicit none integer :: status status = chmod('test.dat','u+x') print *, 'Status: ', status end program chmod_test _Standard_: GNU extension  File: gfortran.info, Node: CMPLX, Next: CO_BROADCAST, Prev: CHMOD, Up: Intrinsic Procedures 8.62 ‘CMPLX’ -- Complex conversion function =========================================== _Synopsis_: ‘RESULT = CMPLX(X [, Y [, KIND]])’ _Description_: ‘CMPLX(X [, Y [, KIND]])’ returns a complex number where X is converted to the real component. If Y is present it is converted to the imaginary component. If Y is not present then the imaginary component is set to 0.0. If X is complex then Y must not be present. _Class_: Elemental function _Arguments_: X The type may be ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’. Y (Optional; only allowed if X is not ‘COMPLEX’.) May be ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of ‘COMPLEX’ type, with a kind equal to KIND if it is specified. If KIND is not specified, the result is of the default ‘COMPLEX’ kind, regardless of the kinds of X and Y. _Example_: program test_cmplx integer :: i = 42 real :: x = 3.14 complex :: z z = cmplx(i, x) print *, z, cmplx(x) end program test_cmplx _Standard_: Fortran 77 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note COMPLEX::  File: gfortran.info, Node: CO_BROADCAST, Next: CO_MAX, Prev: CMPLX, Up: Intrinsic Procedures 8.63 ‘CO_BROADCAST’ -- Copy a value to all images the current set of images =========================================================================== _Synopsis_: ‘CALL CO_BROADCAST(A, SOURCE_IMAGE [, STAT, ERRMSG])’ _Description_: ‘CO_BROADCAST’ copies the value of argument A on the image with image index ‘SOURCE_IMAGE’ to all images in the current team. A becomes defined as if by intrinsic assignment. If the execution was successful and STAT is present, it is assigned the value zero. If the execution failed, STAT gets assigned a nonzero value and, if present, ERRMSG gets assigned a value describing the occurred error. _Class_: Collective subroutine _Arguments_: A INTENT(INOUT) argument; shall have the same dynamic type and type parameters on all images of the current team. If it is an array, it shall have the same shape on all images. SOURCE_IMAGE a scalar integer expression. It shall have the same value on all images and refer to an image of the current team. STAT (optional) a scalar integer variable ERRMSG (optional) a scalar character variable _Example_: program test integer :: val(3) if (this_image() == 1) then val = [1, 5, 3] end if call co_broadcast (val, source_image=1) print *, this_image, ":", val end program test _Standard_: Technical Specification (TS) 18508 or later _See also_: *note CO_MAX::, *note CO_MIN::, *note CO_SUM::, *note CO_REDUCE::  File: gfortran.info, Node: CO_MAX, Next: CO_MIN, Prev: CO_BROADCAST, Up: Intrinsic Procedures 8.64 ‘CO_MAX’ -- Maximal value on the current set of images =========================================================== _Synopsis_: ‘CALL CO_MAX(A [, RESULT_IMAGE, STAT, ERRMSG])’ _Description_: ‘CO_MAX’ determines element-wise the maximal value of A on all images of the current team. If RESULT_IMAGE is present, the maximum values are returned in A on the specified image only and the value of A on the other images become undefined. If RESULT_IMAGE is not present, the value is returned on all images. If the execution was successful and STAT is present, it is assigned the value zero. If the execution failed, STAT gets assigned a nonzero value and, if present, ERRMSG gets assigned a value describing the occurred error. _Class_: Collective subroutine _Arguments_: A shall be an integer, real or character variable, which has the same type and type parameters on all images of the team. RESULT_IMAGE (optional) a scalar integer expression; if present, it shall have the same value on all images and refer to an image of the current team. STAT (optional) a scalar integer variable ERRMSG (optional) a scalar character variable _Example_: program test integer :: val val = this_image () call co_max (val, result_image=1) if (this_image() == 1) then write(*,*) "Maximal value", val ! prints num_images() end if end program test _Standard_: Technical Specification (TS) 18508 or later _See also_: *note CO_MIN::, *note CO_SUM::, *note CO_REDUCE::, *note CO_BROADCAST::  File: gfortran.info, Node: CO_MIN, Next: CO_REDUCE, Prev: CO_MAX, Up: Intrinsic Procedures 8.65 ‘CO_MIN’ -- Minimal value on the current set of images =========================================================== _Synopsis_: ‘CALL CO_MIN(A [, RESULT_IMAGE, STAT, ERRMSG])’ _Description_: ‘CO_MIN’ determines element-wise the minimal value of A on all images of the current team. If RESULT_IMAGE is present, the minimal values are returned in A on the specified image only and the value of A on the other images become undefined. If RESULT_IMAGE is not present, the value is returned on all images. If the execution was successful and STAT is present, it is assigned the value zero. If the execution failed, STAT gets assigned a nonzero value and, if present, ERRMSG gets assigned a value describing the occurred error. _Class_: Collective subroutine _Arguments_: A shall be an integer, real or character variable, which has the same type and type parameters on all images of the team. RESULT_IMAGE (optional) a scalar integer expression; if present, it shall have the same value on all images and refer to an image of the current team. STAT (optional) a scalar integer variable ERRMSG (optional) a scalar character variable _Example_: program test integer :: val val = this_image () call co_min (val, result_image=1) if (this_image() == 1) then write(*,*) "Minimal value", val ! prints 1 end if end program test _Standard_: Technical Specification (TS) 18508 or later _See also_: *note CO_MAX::, *note CO_SUM::, *note CO_REDUCE::, *note CO_BROADCAST::  File: gfortran.info, Node: CO_REDUCE, Next: CO_SUM, Prev: CO_MIN, Up: Intrinsic Procedures 8.66 ‘CO_REDUCE’ -- Reduction of values on the current set of images ==================================================================== _Synopsis_: ‘CALL CO_REDUCE(A, OPERATION, [, RESULT_IMAGE, STAT, ERRMSG])’ _Description_: ‘CO_REDUCE’ determines element-wise the reduction of the value of A on all images of the current team. The pure function passed as OPERATION is used to pairwise reduce the values of A by passing either the value of A of different images or the result values of such a reduction as argument. If A is an array, the deduction is done element wise. If RESULT_IMAGE is present, the result values are returned in A on the specified image only and the value of A on the other images become undefined. If RESULT_IMAGE is not present, the value is returned on all images. If the execution was successful and STAT is present, it is assigned the value zero. If the execution failed, STAT gets assigned a nonzero value and, if present, ERRMSG gets assigned a value describing the occurred error. _Class_: Collective subroutine _Arguments_: A is an ‘INTENT(INOUT)’ argument and shall be nonpolymorphic. If it is allocatable, it shall be allocated; if it is a pointer, it shall be associated. A shall have the same type and type parameters on all images of the team; if it is an array, it shall have the same shape on all images. OPERATION pure function with two scalar nonallocatable arguments, which shall be nonpolymorphic and have the same type and type parameters as A. The function shall return a nonallocatable scalar of the same type and type parameters as A. The function shall be the same on all images and with regards to the arguments mathematically commutative and associative. Note that OPERATION may not be an elemental function, unless it is an intrisic function. RESULT_IMAGE (optional) a scalar integer expression; if present, it shall have the same value on all images and refer to an image of the current team. STAT (optional) a scalar integer variable ERRMSG (optional) a scalar character variable _Example_: program test integer :: val val = this_image () call co_reduce (val, result_image=1, operation=myprod) if (this_image() == 1) then write(*,*) "Product value", val ! prints num_images() factorial end if contains pure function myprod(a, b) integer, value :: a, b integer :: myprod myprod = a * b end function myprod end program test _Notes_: While the rules permit in principle an intrinsic function, none of the intrinsics in the standard fulfill the criteria of having a specific function, which takes two arguments of the same type and returning that type as result. _Standard_: Technical Specification (TS) 18508 or later _See also_: *note CO_MIN::, *note CO_MAX::, *note CO_SUM::, *note CO_BROADCAST::  File: gfortran.info, Node: CO_SUM, Next: COMMAND_ARGUMENT_COUNT, Prev: CO_REDUCE, Up: Intrinsic Procedures 8.67 ‘CO_SUM’ -- Sum of values on the current set of images =========================================================== _Synopsis_: ‘CALL CO_SUM(A [, RESULT_IMAGE, STAT, ERRMSG])’ _Description_: ‘CO_SUM’ sums up the values of each element of A on all images of the current team. If RESULT_IMAGE is present, the summed-up values are returned in A on the specified image only and the value of A on the other images become undefined. If RESULT_IMAGE is not present, the value is returned on all images. If the execution was successful and STAT is present, it is assigned the value zero. If the execution failed, STAT gets assigned a nonzero value and, if present, ERRMSG gets assigned a value describing the occurred error. _Class_: Collective subroutine _Arguments_: A shall be an integer, real or complex variable, which has the same type and type parameters on all images of the team. RESULT_IMAGE (optional) a scalar integer expression; if present, it shall have the same value on all images and refer to an image of the current team. STAT (optional) a scalar integer variable ERRMSG (optional) a scalar character variable _Example_: program test integer :: val val = this_image () call co_sum (val, result_image=1) if (this_image() == 1) then write(*,*) "The sum is ", val ! prints (n**2 + n)/2, ! with n = num_images() end if end program test _Standard_: Technical Specification (TS) 18508 or later _See also_: *note CO_MAX::, *note CO_MIN::, *note CO_REDUCE::, *note CO_BROADCAST::  File: gfortran.info, Node: COMMAND_ARGUMENT_COUNT, Next: COMPILER_OPTIONS, Prev: CO_SUM, Up: Intrinsic Procedures 8.68 ‘COMMAND_ARGUMENT_COUNT’ -- Get number of command line arguments ===================================================================== _Synopsis_: ‘RESULT = COMMAND_ARGUMENT_COUNT()’ _Description_: ‘COMMAND_ARGUMENT_COUNT’ returns the number of arguments passed on the command line when the containing program was invoked. _Class_: Inquiry function _Arguments_: None _Return value_: The return value is an ‘INTEGER’ of default kind. _Example_: program test_command_argument_count integer :: count count = command_argument_count() print *, count end program test_command_argument_count _Standard_: Fortran 2003 and later _See also_: *note GET_COMMAND::, *note GET_COMMAND_ARGUMENT::  File: gfortran.info, Node: COMPILER_OPTIONS, Next: COMPILER_VERSION, Prev: COMMAND_ARGUMENT_COUNT, Up: Intrinsic Procedures 8.69 ‘COMPILER_OPTIONS’ -- Options passed to the compiler ========================================================= _Synopsis_: ‘STR = COMPILER_OPTIONS()’ _Description_: ‘COMPILER_OPTIONS’ returns a string with the options used for compiling. _Class_: Inquiry function of the module ‘ISO_FORTRAN_ENV’ _Arguments_: None _Return value_: The return value is a default-kind string with system-dependent length. It contains the compiler flags used to compile the file that called the ‘COMPILER_OPTIONS’ intrinsic. _Example_: use iso_fortran_env print '(4a)', 'This file was compiled by ', & compiler_version(), ' using the options ', & compiler_options() end _Standard_: Fortran 2008 _See also_: *note COMPILER_VERSION::, *note ISO_FORTRAN_ENV::  File: gfortran.info, Node: COMPILER_VERSION, Next: COMPLEX, Prev: COMPILER_OPTIONS, Up: Intrinsic Procedures 8.70 ‘COMPILER_VERSION’ -- Compiler version string ================================================== _Synopsis_: ‘STR = COMPILER_VERSION()’ _Description_: ‘COMPILER_VERSION’ returns a string with the name and the version of the compiler. _Class_: Inquiry function of the module ‘ISO_FORTRAN_ENV’ _Arguments_: None _Return value_: The return value is a default-kind string with system-dependent length. It contains the name of the compiler and its version number. _Example_: use iso_fortran_env print '(4a)', 'This file was compiled by ', & compiler_version(), ' using the options ', & compiler_options() end _Standard_: Fortran 2008 _See also_: *note COMPILER_OPTIONS::, *note ISO_FORTRAN_ENV::  File: gfortran.info, Node: COMPLEX, Next: CONJG, Prev: COMPILER_VERSION, Up: Intrinsic Procedures 8.71 ‘COMPLEX’ -- Complex conversion function ============================================= _Synopsis_: ‘RESULT = COMPLEX(X, Y)’ _Description_: ‘COMPLEX(X, Y)’ returns a complex number where X is converted to the real component and Y is converted to the imaginary component. _Class_: Elemental function _Arguments_: X The type may be ‘INTEGER’ or ‘REAL’. Y The type may be ‘INTEGER’ or ‘REAL’. _Return value_: If X and Y are both of ‘INTEGER’ type, then the return value is of default ‘COMPLEX’ type. If X and Y are of ‘REAL’ type, or one is of ‘REAL’ type and one is of ‘INTEGER’ type, then the return value is of ‘COMPLEX’ type with a kind equal to that of the ‘REAL’ argument with the highest precision. _Example_: program test_complex integer :: i = 42 real :: x = 3.14 print *, complex(i, x) end program test_complex _Standard_: GNU extension _See also_: *note CMPLX::  File: gfortran.info, Node: CONJG, Next: COS, Prev: COMPLEX, Up: Intrinsic Procedures 8.72 ‘CONJG’ -- Complex conjugate function ========================================== _Synopsis_: ‘Z = CONJG(Z)’ _Description_: ‘CONJG(Z)’ returns the conjugate of Z. If Z is ‘(x, y)’ then the result is ‘(x, -y)’ _Class_: Elemental function _Arguments_: Z The type shall be ‘COMPLEX’. _Return value_: The return value is of type ‘COMPLEX’. _Example_: program test_conjg complex :: z = (2.0, 3.0) complex(8) :: dz = (2.71_8, -3.14_8) z= conjg(z) print *, z dz = dconjg(dz) print *, dz end program test_conjg _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DCONJG(Z)’ ‘COMPLEX(8) Z’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 77 and later, has an overload that is a GNU extension  File: gfortran.info, Node: COS, Next: COSD, Prev: CONJG, Up: Intrinsic Procedures 8.73 ‘COS’ -- Cosine function ============================= _Synopsis_: ‘RESULT = COS(X)’ _Description_: ‘COS(X)’ computes the cosine of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value is of the same type and kind as X. The real part of the result is in radians. If X is of the type ‘REAL’, the return value lies in the range -1 \leq \cos (x) \leq 1. _Example_: program test_cos real :: x = 0.0 x = cos(x) end program test_cos _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘COS(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DCOS(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later ‘CCOS(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ Fortran 77 and later ‘ZCOS(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDCOS(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 77 and later, has overloads that are GNU extensions _See also_: Inverse function: *note ACOS:: Degrees function: *note COSD::  File: gfortran.info, Node: COSD, Next: COSH, Prev: COS, Up: Intrinsic Procedures 8.74 ‘COSD’ -- Cosine function, degrees ======================================= _Synopsis_: ‘RESULT = COSD(X)’ _Description_: ‘COSD(X)’ computes the cosine of X in degrees. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of the same type and kind as X and lies in the range -1 \leq \cosd (x) \leq 1. _Example_: program test_cosd real :: x = 0.0 x = cosd(x) end program test_cosd _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘COSD(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 2023 ‘DCOSD(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension ‘CCOSD(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ GNU extension ‘ZCOSD(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDCOSD(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Inverse function: *note ACOSD:: Radians function: *note COS::  File: gfortran.info, Node: COSH, Next: COTAN, Prev: COSD, Up: Intrinsic Procedures 8.75 ‘COSH’ -- Hyperbolic cosine function ========================================= _Synopsis_: ‘X = COSH(X)’ _Description_: ‘COSH(X)’ computes the hyperbolic cosine of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X. If X is complex, the imaginary part of the result is in radians. If X is ‘REAL’, the return value has a lower bound of one, \cosh (x) \geq 1. _Example_: program test_cosh real(8) :: x = 1.0_8 x = cosh(x) end program test_cosh _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘COSH(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DCOSH(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, for a complex argument Fortran 2008 or later _See also_: Inverse function: *note ACOSH::  File: gfortran.info, Node: COTAN, Next: COTAND, Prev: COSH, Up: Intrinsic Procedures 8.76 ‘COTAN’ -- Cotangent function ================================== _Synopsis_: ‘RESULT = COTAN(X)’ _Description_: ‘COTAN(X)’ computes the cotangent of X. Equivalent to ‘COS(x)’ divided by ‘SIN(x)’, or ‘1 / TAN(x)’. This function is for compatibility only and should be avoided in favor of standard constructs wherever possible. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X, and its value is in radians. _Example_: program test_cotan real(8) :: x = 0.165_8 x = cotan(x) end program test_cotan _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘COTAN(X)’ ‘REAL(4) X’ ‘REAL(4)’ GNU extension ‘DCOTAN(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: GNU extension, enabled with ‘-fdec-math’. _See also_: Converse function: *note TAN:: Degrees function: *note COTAND::  File: gfortran.info, Node: COTAND, Next: COUNT, Prev: COTAN, Up: Intrinsic Procedures 8.77 ‘COTAND’ -- Cotangent function, degrees ============================================ _Synopsis_: ‘RESULT = COTAND(X)’ _Description_: ‘COTAND(X)’ computes the cotangent of X in degrees. Equivalent to ‘COSD(x)’ divided by ‘SIND(x)’, or ‘1 / TAND(x)’. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value has same type and kind as X, and its value is in degrees. _Example_: program test_cotand real(8) :: x = 0.165_8 x = cotand(x) end program test_cotand _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘COTAND(X)’ ‘REAL(4) X’ ‘REAL(4)’ GNU extension ‘DCOTAND(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: GNU extension. This function is for compatibility only and should be avoided in favor of standard constructs wherever possible. _See also_: Converse function: *note TAND:: Radians function: *note COTAN::  File: gfortran.info, Node: COUNT, Next: CPU_TIME, Prev: COTAND, Up: Intrinsic Procedures 8.78 ‘COUNT’ -- Count function ============================== _Synopsis_: ‘RESULT = COUNT(MASK [, DIM, KIND])’ _Description_: Counts the number of ‘.TRUE.’ elements in a logical MASK, or, if the DIM argument is supplied, counts the number of elements along each row of the array in the DIM direction. If the array has zero size, or all of the elements of MASK are ‘.FALSE.’, then the result is ‘0’. _Class_: Transformational function _Arguments_: MASK The type shall be ‘LOGICAL’. DIM (Optional) The type shall be ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the shape of ARRAY with the DIM dimension removed. _Example_: program test_count integer, dimension(2,3) :: a, b logical, dimension(2,3) :: mask a = reshape( (/ 1, 2, 3, 4, 5, 6 /), (/ 2, 3 /)) b = reshape( (/ 0, 7, 3, 4, 5, 8 /), (/ 2, 3 /)) print '(3i3)', a(1,:) print '(3i3)', a(2,:) print * print '(3i3)', b(1,:) print '(3i3)', b(2,:) print * mask = a.ne.b print '(3l3)', mask(1,:) print '(3l3)', mask(2,:) print * print '(3i3)', count(mask) print * print '(3i3)', count(mask, 1) print * print '(3i3)', count(mask, 2) end program test_count _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later  File: gfortran.info, Node: CPU_TIME, Next: CSHIFT, Prev: COUNT, Up: Intrinsic Procedures 8.79 ‘CPU_TIME’ -- CPU elapsed time in seconds ============================================== _Synopsis_: ‘CALL CPU_TIME(TIME)’ _Description_: Returns a ‘REAL’ value representing the elapsed CPU time in seconds. This is useful for testing segments of code to determine execution time. If a time source is available, time is reported with microsecond resolution. If no time source is available, TIME is set to ‘-1.0’. Note that TIME may contain a system-dependent arbitrary offset and may not start with ‘0.0’. For ‘CPU_TIME’, the absolute value is meaningless; only differences between subsequent calls to this subroutine, as shown in the example below, should be used. _Class_: Subroutine _Arguments_: TIME The type shall be ‘REAL’ with ‘INTENT(OUT)’. _Return value_: None _Example_: program test_cpu_time real :: start, finish call cpu_time(start) ! put code to test here call cpu_time(finish) print '("Time = ",f6.3," seconds.")',finish-start end program test_cpu_time _Standard_: Fortran 95 and later _See also_: *note SYSTEM_CLOCK::, *note DATE_AND_TIME::  File: gfortran.info, Node: CSHIFT, Next: CTIME, Prev: CPU_TIME, Up: Intrinsic Procedures 8.80 ‘CSHIFT’ -- Circular shift elements of an array ==================================================== _Synopsis_: ‘RESULT = CSHIFT(ARRAY, SHIFT [, DIM])’ _Description_: ‘CSHIFT(ARRAY, SHIFT [, DIM])’ performs a circular shift on elements of ARRAY along the dimension of DIM. If DIM is omitted it is taken to be ‘1’. DIM is a scalar of type ‘INTEGER’ in the range of 1 \leq DIM \leq n) where n is the rank of ARRAY. If the rank of ARRAY is one, then all elements of ARRAY are shifted by SHIFT places. If rank is greater than one, then all complete rank one sections of ARRAY along the given dimension are shifted. Elements shifted out one end of each rank one section are shifted back in the other end. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of any type. SHIFT The type shall be ‘INTEGER’. DIM The type shall be ‘INTEGER’. _Notes_: ARRAY can also be ‘UNSIGNED’. _Return value_: Returns an array of same type and rank as the ARRAY argument. _Example_: program test_cshift integer, dimension(3,3) :: a a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /)) print '(3i3)', a(1,:) print '(3i3)', a(2,:) print '(3i3)', a(3,:) a = cshift(a, SHIFT=(/1, 2, -1/), DIM=2) print * print '(3i3)', a(1,:) print '(3i3)', a(2,:) print '(3i3)', a(3,:) end program test_cshift _Standard_: Fortran 90 and later  File: gfortran.info, Node: CTIME, Next: DATE_AND_TIME, Prev: CSHIFT, Up: Intrinsic Procedures 8.81 ‘CTIME’ -- Convert a time into a string ============================================ _Synopsis_: ‘CALL CTIME(TIME, RESULT)’. ‘RESULT = CTIME(TIME)’. _Description_: ‘CTIME’ converts a system time value, such as returned by *note TIME8::, to a string. The output is of the form ‘Sat Aug 19 18:13:14 1995’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: TIME The type shall be of type ‘INTEGER’. RESULT The type shall be of type ‘CHARACTER’ and of default kind. It is an ‘INTENT(OUT)’ argument. If the length of this variable is too short for the time and date string to fit completely, it is blank on procedure return. _Return value_: The converted date and time as a string. _Example_: program test_ctime integer(8) :: i character(len=30) :: date i = time8() ! Do something, main part of the program call ctime(i,date) print *, 'Program was started on ', date end program test_ctime _Standard_: GNU extension _See also_: *note DATE_AND_TIME::, *note GMTIME::, *note LTIME::, *note TIME::, *note TIME8::  File: gfortran.info, Node: DATE_AND_TIME, Next: DBLE, Prev: CTIME, Up: Intrinsic Procedures 8.82 ‘DATE_AND_TIME’ -- Date and time subroutine ================================================ _Synopsis_: ‘CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])’ _Description_: ‘DATE_AND_TIME(DATE, TIME, ZONE, VALUES)’ gets the corresponding date and time information from the real-time system clock. DATE is ‘INTENT(OUT)’ and of the form ccyymmdd. TIME is ‘INTENT(OUT)’ and of the form hhmmss.sss. ZONE is ‘INTENT(OUT)’ and of the form (+-)hhmm, representing the difference with respect to Coordinated Universal Time (UTC). Unavailable time and date parameters return blanks. VALUES is ‘INTENT(OUT)’ and provides the following: ‘VALUES(1)’:The year, including the century ‘VALUES(2)’:The month of the year ‘VALUES(3)’:The day of the month ‘VALUES(4)’:The time difference from UTC in minutes ‘VALUES(5)’:The hour of the day ‘VALUES(6)’:The minutes of the hour ‘VALUES(7)’:The seconds of the minute ‘VALUES(8)’:The milliseconds of the second _Class_: Subroutine _Arguments_: DATE (Optional) Scalar of type default ‘CHARACTER’. Recommended length is 8 or larger. TIME (Optional) Scalar of type default ‘CHARACTER’. Recommended length is 10 or larger. ZONE (Optional) Scalar of type default ‘CHARACTER’. Recommended length is 5 or larger. VALUES (Optional) Rank-1 array of type ‘INTEGER’ with a decimal exponent range of at least four and array size at least 8. _Return value_: None _Example_: program test_time_and_date character(8) :: date character(10) :: time character(5) :: zone integer,dimension(8) :: values ! using keyword arguments call date_and_time(date,time,zone,values) call date_and_time(DATE=date,ZONE=zone) call date_and_time(TIME=time) call date_and_time(VALUES=values) print '(a,2x,a,2x,a)', date, time, zone print '(8i5)', values end program test_time_and_date _Standard_: Fortran 90 and later _See also_: *note CPU_TIME::, *note SYSTEM_CLOCK::  File: gfortran.info, Node: DBLE, Next: DCMPLX, Prev: DATE_AND_TIME, Up: Intrinsic Procedures 8.83 ‘DBLE’ -- Double conversion function ========================================= _Synopsis_: ‘RESULT = DBLE(A)’ _Description_: ‘DBLE(A)’ Converts A to double precision real type. _Class_: Elemental function _Arguments_: A The type shall be ‘INTEGER’, ‘REAL’, or ‘COMPLEX’. _Return value_: The return value is of type double precision real. _Example_: program test_dble real :: x = 2.18 integer :: i = 5 complex :: z = (2.3,1.14) print *, dble(x), dble(i), dble(z) end program test_dble _Standard_: Fortran 77 and later _See also_: *note REAL::  File: gfortran.info, Node: DCMPLX, Next: DIGITS, Prev: DBLE, Up: Intrinsic Procedures 8.84 ‘DCMPLX’ -- Double complex conversion function =================================================== _Synopsis_: ‘RESULT = DCMPLX(X [, Y])’ _Description_: ‘DCMPLX(X [,Y])’ returns a double complex number where X is converted to the real component. If Y is present it is converted to the imaginary component. If Y is not present then the imaginary component is set to 0.0. If X is complex then Y must not be present. _Class_: Elemental function _Arguments_: X The type may be ‘INTEGER’, ‘REAL’, or ‘COMPLEX’. Y (Optional if X is not ‘COMPLEX’.) May be ‘INTEGER’ or ‘REAL’. _Return value_: The return value is of type ‘COMPLEX(8)’ _Example_: program test_dcmplx integer :: i = 42 real :: x = 3.14 complex :: z z = cmplx(i, x) print *, dcmplx(i) print *, dcmplx(x) print *, dcmplx(z) print *, dcmplx(x,i) end program test_dcmplx _Standard_: GNU extension  File: gfortran.info, Node: DIGITS, Next: DIM, Prev: DCMPLX, Up: Intrinsic Procedures 8.85 ‘DIGITS’ -- Significant binary digits function =================================================== _Synopsis_: ‘RESULT = DIGITS(X)’ _Description_: ‘DIGITS(X)’ returns the number of significant binary digits of the internal model representation of X. For example, on a system using a 32-bit floating point representation, a default real number would likely return 24. _Class_: Inquiry function _Arguments_: X The type may be ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’. _Return value_: The return value is of type ‘INTEGER’. _Example_: program test_digits integer :: i = 12345 real :: x = 3.143 real(8) :: y = 2.33 print *, digits(i) print *, digits(x) print *, digits(y) end program test_digits _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: DIM, Next: DOT_PRODUCT, Prev: DIGITS, Up: Intrinsic Procedures 8.86 ‘DIM’ -- Positive difference ================================= _Synopsis_: ‘RESULT = DIM(X, Y)’ _Description_: ‘DIM(X,Y)’ returns the difference ‘X-Y’ if the result is positive; otherwise returns zero. _Class_: Elemental function _Arguments_: X The type shall be ‘INTEGER’ or ‘REAL’ Y The type shall be the same type and kind as X. (As a GNU extension, arguments of different kinds are permitted.) _Return value_: The return value is of type ‘INTEGER’ or ‘REAL’. (As a GNU extension, kind is the largest kind of the actual arguments.) _Example_: program test_dim integer :: i real(8) :: x i = dim(4, 15) x = dim(4.345_8, 2.111_8) print *, i print *, x end program test_dim _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DIM(X,Y)’ ‘REAL(4) X, Y’ ‘REAL(4)’ Fortran 77 and later ‘IDIM(X,Y)’ ‘INTEGER(4) X, Y’ ‘INTEGER(4)’ Fortran 77 and later ‘DDIM(X,Y)’ ‘REAL(8) X, Y’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later  File: gfortran.info, Node: DOT_PRODUCT, Next: DPROD, Prev: DIM, Up: Intrinsic Procedures 8.87 ‘DOT_PRODUCT’ -- Dot product function ========================================== _Synopsis_: ‘RESULT = DOT_PRODUCT(VECTOR_A, VECTOR_B)’ _Description_: ‘DOT_PRODUCT(VECTOR_A, VECTOR_B)’ computes the dot product multiplication of two vectors VECTOR_A and VECTOR_B. The two vectors may be either numeric or logical and must be arrays of rank one and of equal size. If the vectors are ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’, the result is ‘SUM(VECTOR_A*VECTOR_B)’. If the vectors are ‘COMPLEX’, the result is ‘SUM(CONJG(VECTOR_A)*VECTOR_B)’. If the vectors are ‘LOGICAL’, the result is ‘ANY(VECTOR_A .AND. VECTOR_B)’. If one of VECTOR_A or VECTOR_B is ‘UNSIGNED’, the other one shall also be ‘UNSIGNED’. _Class_: Transformational function _Arguments_: VECTOR_A The type shall be numeric or ‘LOGICAL’, rank 1. If VECTOR_B is ‘UNSIGNED’, VECTOR_A shall also be unsigned. VECTOR_B The type shall if VECTOR_A is of numeric type or ‘LOGICAL’ if VECTOR_A is of type ‘LOGICAL’. VECTOR_B shall be a rank-one array. If VECTOR_A is ‘UNSIGNED’, VECTOR_B shall also be unsigned. _Return value_: If the arguments are numeric, the return value is a scalar of numeric type, ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’. If the arguments are ‘LOGICAL’, the return value is ‘.TRUE.’ or ‘.FALSE.’. _Example_: program test_dot_prod integer, dimension(3) :: a, b a = (/ 1, 2, 3 /) b = (/ 4, 5, 6 /) print '(3i3)', a print * print '(3i3)', b print * print *, dot_product(a,b) end program test_dot_prod _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: DPROD, Next: DREAL, Prev: DOT_PRODUCT, Up: Intrinsic Procedures 8.88 ‘DPROD’ -- Double product function ======================================= _Synopsis_: ‘RESULT = DPROD(X, Y)’ _Description_: ‘DPROD(X,Y)’ returns the product ‘X*Y’. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. Y The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL(8)’. _Example_: program test_dprod real :: x = 5.2 real :: y = 2.3 real(8) :: d d = dprod(x,y) print *, d end program test_dprod _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DPROD(X,Y)’ ‘REAL(4) X, Y’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later  File: gfortran.info, Node: DREAL, Next: DSHIFTL, Prev: DPROD, Up: Intrinsic Procedures 8.89 ‘DREAL’ -- Double real part function ========================================= _Synopsis_: ‘RESULT = DREAL(A)’ _Description_: ‘DREAL(Z)’ returns the real part of complex variable Z. _Class_: Elemental function _Arguments_: A The type shall be ‘COMPLEX(8)’. _Return value_: The return value is of type ‘REAL(8)’. _Example_: program test_dreal complex(8) :: z = (1.3_8,7.2_8) print *, dreal(z) end program test_dreal _Standard_: GNU extension _See also_: *note AIMAG::  File: gfortran.info, Node: DSHIFTL, Next: DSHIFTR, Prev: DREAL, Up: Intrinsic Procedures 8.90 ‘DSHIFTL’ -- Combined left shift ===================================== _Synopsis_: ‘RESULT = DSHIFTL(I, J, SHIFT)’ _Description_: ‘DSHIFTL(I, J, SHIFT)’ combines bits of I and J. The rightmost SHIFT bits of the result are the leftmost SHIFT bits of J, and the remaining bits are the rightmost bits of I. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’, ‘UNSIGNED’ or a BOZ constant. J Shall be of type ‘INTEGER’, ‘UNSIGNED’ or a BOZ constant. If both I and J have ‘INTEGER’ or ‘UNSIGNED’ type, then they shall have the same type and kind type parameter. I and J shall not both be BOZ constants. SHIFT Shall be of type ‘INTEGER’. It shall be nonnegative. If I is not a BOZ constant, then SHIFT shall be less than or equal to ‘BIT_SIZE(I)’; otherwise, SHIFT shall be less than or equal to ‘BIT_SIZE(J)’. _Return value_: The return value is the same type and type kind parameter as I or, if I is a BOZ constant, J. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note DSHIFTR::  File: gfortran.info, Node: DSHIFTR, Next: DTIME, Prev: DSHIFTL, Up: Intrinsic Procedures 8.91 ‘DSHIFTR’ -- Combined right shift ====================================== _Synopsis_: ‘RESULT = DSHIFTR(I, J, SHIFT)’ _Description_: ‘DSHIFTR(I, J, SHIFT)’ combines bits of I and J. The leftmost SHIFT bits of the result are the rightmost SHIFT bits of I, and the remaining bits are the leftmost bits of J. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’, ‘UNSIGNED’ or a BOZ constant. J Shall be of type ‘INTEGER’, ‘UNSIGNED’ or a BOZ constant. If both I and J have ‘INTEGER’ or ‘UNSIGNED’ type, then they shall have the same type and kind type parameter. I and J shall not both be BOZ constants. SHIFT Shall be of type ‘INTEGER’. It shall be nonnegative. If I is not a BOZ constant, then SHIFT shall be less than or equal to ‘BIT_SIZE(I)’; otherwise, SHIFT shall be less than or equal to ‘BIT_SIZE(J)’. _Return value_: The return value is the same type and type kind parameter as I or, if I is a BOZ constant, J. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note DSHIFTL::  File: gfortran.info, Node: DTIME, Next: EOSHIFT, Prev: DSHIFTR, Up: Intrinsic Procedures 8.92 ‘DTIME’ -- Execution time subroutine (or function) ======================================================= _Synopsis_: ‘CALL DTIME(VALUES, TIME)’. ‘TIME = DTIME(VALUES)’, (not recommended). _Description_: ‘DTIME(VALUES, TIME)’ initially returns the number of seconds of runtime since the start of the process's execution in TIME. VALUES returns the user and system components of this time in ‘VALUES(1)’ and ‘VALUES(2)’ respectively. TIME is equal to ‘VALUES(1) + VALUES(2)’. Subsequent invocations of ‘DTIME’ return values accumulated since the previous invocation. On some systems, the underlying timings are represented using types with sufficiently small limits that overflows (wrap around) are possible, such as 32-bit types. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program. Please note that this implementation is thread safe if used within OpenMP directives, i.e., its state is consistent while called from multiple threads. However, if ‘DTIME’ is called from multiple threads, the result is still the time since the last invocation. This may not give the intended results. If possible, use ‘CPU_TIME’ instead. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. VALUES and TIME are ‘INTENT(OUT)’ and provide the following: ‘VALUES(1)’:User time in seconds. ‘VALUES(2)’:System time in seconds. ‘TIME’: Run time since start in seconds. _Class_: Subroutine, function _Arguments_: VALUES The type shall be ‘REAL(4), DIMENSION(2)’. TIME The type shall be ‘REAL(4)’. _Return value_: Elapsed time in seconds since the last invocation or since the start of program execution if not called before. _Example_: program test_dtime integer(8) :: i, j real, dimension(2) :: tarray real :: result call dtime(tarray, result) print *, result print *, tarray(1) print *, tarray(2) do i=1,100000000 ! Just a delay j = i * i - i end do call dtime(tarray, result) print *, result print *, tarray(1) print *, tarray(2) end program test_dtime _Standard_: GNU extension _See also_: *note CPU_TIME::  File: gfortran.info, Node: EOSHIFT, Next: EPSILON, Prev: DTIME, Up: Intrinsic Procedures 8.93 ‘EOSHIFT’ -- End-off shift elements of an array ==================================================== _Synopsis_: ‘RESULT = EOSHIFT(ARRAY, SHIFT [, BOUNDARY, DIM])’ _Description_: ‘EOSHIFT(ARRAY, SHIFT[, BOUNDARY, DIM])’ performs an end-off shift on elements of ARRAY along the dimension of DIM. If DIM is omitted it is taken to be ‘1’. DIM is a scalar of type ‘INTEGER’ in the range of 1 \leq DIM \leq n) where n is the rank of ARRAY. If the rank of ARRAY is one, then all elements of ARRAY are shifted by SHIFT places. If rank is greater than one, then all complete rank one sections of ARRAY along the given dimension are shifted. Elements shifted out one end of each rank one section are dropped. If BOUNDARY is present then the corresponding value of from BOUNDARY is copied back in the other end. If BOUNDARY is not present then the following are copied in depending on the type of ARRAY. _Array _Boundary Value_ Type_ Numeric 0 of the type and kind of ARRAY. Logical ‘.FALSE.’. Character(LEN)LEN blanks. _Class_: Transformational function _Arguments_: ARRAY May be any type, not scalar. SHIFT The type shall be ‘INTEGER’. BOUNDARY Same type as ARRAY. DIM The type shall be ‘INTEGER’. _Notes_: ARRAY can also be ‘UNSIGNED’. _Return value_: Returns an array of same type and rank as the ARRAY argument. _Example_: program test_eoshift integer, dimension(3,3) :: a a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /)) print '(3i3)', a(1,:) print '(3i3)', a(2,:) print '(3i3)', a(3,:) a = EOSHIFT(a, SHIFT=(/1, 2, 1/), BOUNDARY=-5, DIM=2) print * print '(3i3)', a(1,:) print '(3i3)', a(2,:) print '(3i3)', a(3,:) end program test_eoshift _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: EPSILON, Next: ERF, Prev: EOSHIFT, Up: Intrinsic Procedures 8.94 ‘EPSILON’ -- Epsilon function ================================== _Synopsis_: ‘RESULT = EPSILON(X)’ _Description_: ‘EPSILON(X)’ returns the smallest number E of the same kind as X such that 1 + E > 1. _Class_: Inquiry function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of same type as the argument. _Example_: program test_epsilon real :: x = 3.143 real(8) :: y = 2.33 print *, EPSILON(x) print *, EPSILON(y) end program test_epsilon _Standard_: Fortran 90 and later  File: gfortran.info, Node: ERF, Next: ERFC, Prev: EPSILON, Up: Intrinsic Procedures 8.95 ‘ERF’ -- Error function ============================ _Synopsis_: ‘RESULT = ERF(X)’ _Description_: ‘ERF(X)’ computes the error function of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’, of the same kind as X and lies in the range -1 \leq erf (x) \leq 1 . _Example_: program test_erf real(8) :: x = 0.17_8 x = erf(x) end program test_erf _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DERF(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later  File: gfortran.info, Node: ERFC, Next: ERFC_SCALED, Prev: ERF, Up: Intrinsic Procedures 8.96 ‘ERFC’ -- Error function ============================= _Synopsis_: ‘RESULT = ERFC(X)’ _Description_: ‘ERFC(X)’ computes the complementary error function of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’ and of the same kind as X. It lies in the range 0 \leq erfc (x) \leq 2 . _Example_: program test_erfc real(8) :: x = 0.17_8 x = erfc(x) end program test_erfc _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DERFC(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later  File: gfortran.info, Node: ERFC_SCALED, Next: ETIME, Prev: ERFC, Up: Intrinsic Procedures 8.97 ‘ERFC_SCALED’ -- Error function ==================================== _Synopsis_: ‘RESULT = ERFC_SCALED(X)’ _Description_: ‘ERFC_SCALED(X)’ computes the exponentially-scaled complementary error function of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’ and of the same kind as X. _Example_: program test_erfc_scaled real(8) :: x = 0.17_8 x = erfc_scaled(x) end program test_erfc_scaled _Standard_: Fortran 2008 and later  File: gfortran.info, Node: ETIME, Next: EVENT_QUERY, Prev: ERFC_SCALED, Up: Intrinsic Procedures 8.98 ‘ETIME’ -- Execution time subroutine (or function) ======================================================= _Synopsis_: ‘CALL ETIME(VALUES, TIME)’. ‘TIME = ETIME(VALUES)’, (not recommended). _Description_: ‘ETIME(VALUES, TIME)’ returns the number of seconds of runtime since the start of the process's execution in TIME. VALUES returns the user and system components of this time in ‘VALUES(1)’ and ‘VALUES(2)’ respectively. TIME is equal to ‘VALUES(1) + VALUES(2)’. On some systems, the underlying timings are represented using types with sufficiently small limits that overflows (wrap around) are possible, such as 32-bit types. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. VALUES and TIME are ‘INTENT(OUT)’ and provide the following: ‘VALUES(1)’:User time in seconds. ‘VALUES(2)’:System time in seconds. ‘TIME’: Run time since start in seconds. _Class_: Subroutine, function _Arguments_: VALUES The type shall be ‘REAL(4), DIMENSION(2)’. TIME The type shall be ‘REAL(4)’. _Return value_: Elapsed time in seconds since the start of program execution. _Example_: program test_etime integer(8) :: i, j real, dimension(2) :: tarray real :: result call ETIME(tarray, result) print *, result print *, tarray(1) print *, tarray(2) do i=1,100000000 ! Just a delay j = i * i - i end do call ETIME(tarray, result) print *, result print *, tarray(1) print *, tarray(2) end program test_etime _Standard_: GNU extension _See also_: *note CPU_TIME::  File: gfortran.info, Node: EVENT_QUERY, Next: EXECUTE_COMMAND_LINE, Prev: ETIME, Up: Intrinsic Procedures 8.99 ‘EVENT_QUERY’ -- Query whether a coarray event has occurred ================================================================ _Synopsis_: ‘CALL EVENT_QUERY (EVENT, COUNT [, STAT])’ _Description_: ‘EVENT_QUERY’ assigns the number of events to COUNT that have been posted to the EVENT variable and not yet been removed by calling ‘EVENT WAIT’. When STAT is present and the invocation is successful, it is assigned the value 0. If it is present and the invocation fails, it is assigned a positive value and COUNT is assigned the value -1. _Class_: subroutine _Arguments_: EVENT (intent(IN)) Scalar of type ‘EVENT_TYPE’, defined in ‘ISO_FORTRAN_ENV’; shall not be coindexed. COUNT (intent(out))Scalar integer with at least the precision of default integer. STAT (optional) Scalar default-kind integer variable. _Example_: program atomic use iso_fortran_env implicit none type(event_type) :: event_value_has_been_set[*] integer :: cnt if (this_image() == 1) then call event_query (event_value_has_been_set, cnt) if (cnt > 0) write(*,*) "Value has been set" elseif (this_image() == 2) then event post (event_value_has_been_set[1]) end if end program atomic _Standard_: TS 18508 or later  File: gfortran.info, Node: EXECUTE_COMMAND_LINE, Next: EXIT, Prev: EVENT_QUERY, Up: Intrinsic Procedures 8.100 ‘EXECUTE_COMMAND_LINE’ -- Execute a shell command ======================================================= _Synopsis_: ‘CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT, CMDMSG ])’ _Description_: ‘EXECUTE_COMMAND_LINE’ runs a shell command, synchronously or asynchronously. The ‘COMMAND’ argument is passed to the shell and executed (The shell is ‘sh’ on Unix systems, and ‘cmd.exe’ on Windows.). If ‘WAIT’ is present and has the value false, the execution of the command is asynchronous if the system supports it; otherwise, the command is executed synchronously using the C library's ‘system’ call. The three last arguments allow the user to get status information. After synchronous execution, ‘EXITSTAT’ contains the integer exit code of the command, as returned by ‘system’. ‘CMDSTAT’ is set to zero if the command line was executed (whatever its exit status was). ‘CMDMSG’ is assigned an error message if an error has occurred. Note that the ‘system’ function need not be thread-safe. It is the responsibility of the user to ensure that ‘system’ is not called concurrently. For asynchronous execution on supported targets, the POSIX ‘posix_spawn’ or ‘fork’ functions are used. Also, a signal handler for the ‘SIGCHLD’ signal is installed. _Class_: Subroutine _Arguments_: COMMAND Shall be a default ‘CHARACTER’ scalar. WAIT (Optional) Shall be a default ‘LOGICAL’ scalar. EXITSTAT (Optional) Shall be an ‘INTEGER’ of the default kind. CMDSTAT (Optional) Shall be an ‘INTEGER’ of the default kind. CMDMSG (Optional) Shall be an ‘CHARACTER’ scalar of the default kind. _Example_: program test_exec integer :: i call execute_command_line ("external_prog.exe", exitstat=i) print *, "Exit status of external_prog.exe was ", i call execute_command_line ("reindex_files.exe", wait=.false.) print *, "Now reindexing files in the background" end program test_exec _Notes_: Because this intrinsic is implemented in terms of the ‘system’ function call, its behavior with respect to signaling is processor dependent. In particular, on POSIX-compliant systems, the ‘SIGINT’ and ‘SIGQUIT’ signals are ignored, and ‘SIGCHLD’ is blocked. As such, if the parent process is terminated, the child process might not be terminated alongside. _Standard_: Fortran 2008 and later _See also_: *note SYSTEM::  File: gfortran.info, Node: EXIT, Next: EXP, Prev: EXECUTE_COMMAND_LINE, Up: Intrinsic Procedures 8.101 ‘EXIT’ -- Exit the program with status. ============================================= _Synopsis_: ‘CALL EXIT([STATUS])’ _Description_: ‘EXIT’ causes immediate termination of the program with status. If status is omitted it returns the canonical _success_ for the system. All Fortran I/O units are closed. _Class_: Subroutine _Arguments_: STATUS Shall be an ‘INTEGER’ of the default kind. _Return value_: ‘STATUS’ is passed to the parent process on exit. _Example_: program test_exit integer :: STATUS = 0 print *, 'This program is going to exit.' call EXIT(STATUS) end program test_exit _Standard_: GNU extension _See also_: *note ABORT::, *note KILL::  File: gfortran.info, Node: EXP, Next: EXPONENT, Prev: EXIT, Up: Intrinsic Procedures 8.102 ‘EXP’ -- Exponential function =================================== _Synopsis_: ‘RESULT = EXP(X)’ _Description_: ‘EXP(X)’ computes the base e exponential of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X. _Example_: program test_exp real :: x = 1.0 x = exp(x) end program test_exp _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘EXP(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DEXP(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later ‘CEXP(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ Fortran 77 and later ‘ZEXP(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDEXP(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 77 and later, has overloads that are GNU extensions  File: gfortran.info, Node: EXPONENT, Next: EXTENDS_TYPE_OF, Prev: EXP, Up: Intrinsic Procedures 8.103 ‘EXPONENT’ -- Exponent function ===================================== _Synopsis_: ‘RESULT = EXPONENT(X)’ _Description_: ‘EXPONENT(X)’ returns the value of the exponent part of X. If X is zero the value returned is zero. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type default ‘INTEGER’. _Example_: program test_exponent real :: x = 1.0 integer :: i i = exponent(x) print *, i print *, exponent(0.0) end program test_exponent _Standard_: Fortran 90 and later  File: gfortran.info, Node: EXTENDS_TYPE_OF, Next: FDATE, Prev: EXPONENT, Up: Intrinsic Procedures 8.104 ‘EXTENDS_TYPE_OF’ -- Query dynamic type for extension =========================================================== _Synopsis_: ‘RESULT = EXTENDS_TYPE_OF(A, MOLD)’ _Description_: Query dynamic type for extension. _Class_: Inquiry function _Arguments_: A Shall be an object of extensible declared type or unlimited polymorphic. MOLD Shall be an object of extensible declared type or unlimited polymorphic. _Return value_: The return value is a scalar of type default logical. It is true if and only if the dynamic type of A is an extension type of the dynamic type of MOLD. _Standard_: Fortran 2003 and later _See also_: *note SAME_TYPE_AS::  File: gfortran.info, Node: FDATE, Next: FGET, Prev: EXTENDS_TYPE_OF, Up: Intrinsic Procedures 8.105 ‘FDATE’ -- Get the current time as a string ================================================= _Synopsis_: ‘CALL FDATE(DATE)’. ‘DATE = FDATE()’. _Description_: ‘FDATE(DATE)’ returns the current date (using the same format as *note CTIME::) in DATE. It is equivalent to ‘CALL CTIME(DATE, TIME())’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: DATE The type shall be of type ‘CHARACTER’ of the default kind. It is an ‘INTENT(OUT)’ argument. If the length of this variable is too short for the date and time string to fit completely, it is blank on procedure return. _Return value_: The current date and time as a string. _Example_: program test_fdate integer(8) :: i, j character(len=30) :: date call fdate(date) print *, 'Program started on ', date do i = 1, 100000000 ! Just a delay j = i * i - i end do call fdate(date) print *, 'Program ended on ', date end program test_fdate _Standard_: GNU extension _See also_: *note DATE_AND_TIME::, *note CTIME::  File: gfortran.info, Node: FGET, Next: FGETC, Prev: FDATE, Up: Intrinsic Procedures 8.106 ‘FGET’ -- Read a single character in stream mode from stdin ================================================================= _Synopsis_: ‘CALL FGET(C [, STATUS])’ ‘STATUS = FGET(C)’ _Description_: Read a single character in stream mode from stdin by bypassing normal formatted output. Stream I/O should not be mixed with normal record-oriented (formatted or unformatted) I/O on the same unit; the results are unpredictable. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. Note that the ‘FGET’ intrinsic is provided for backwards compatibility with ‘g77’. GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability. See also *note Fortran 2003 status::. _Class_: Subroutine, function _Arguments_: C The type shall be ‘CHARACTER’ and of default kind. STATUS (Optional) status flag of type ‘INTEGER’. Returns 0 on success, -1 on end-of-file, and a system specific positive error code otherwise. _Example_: PROGRAM test_fget INTEGER, PARAMETER :: strlen = 100 INTEGER :: status, i = 1 CHARACTER(len=strlen) :: str = "" WRITE (*,*) 'Enter text:' DO CALL fget(str(i:i), status) if (status /= 0 .OR. i > strlen) exit i = i + 1 END DO WRITE (*,*) TRIM(str) END PROGRAM _Standard_: GNU extension _See also_: *note FGETC::, *note FPUT::, *note FPUTC::  File: gfortran.info, Node: FGETC, Next: FINDLOC, Prev: FGET, Up: Intrinsic Procedures 8.107 ‘FGETC’ -- Read a single character in stream mode ======================================================= _Synopsis_: ‘CALL FGETC(UNIT, C [, STATUS])’ ‘STATUS = FGETC(UNIT, C)’ _Description_: Read a single character in stream mode by bypassing normal formatted output. Stream I/O should not be mixed with normal record-oriented (formatted or unformatted) I/O on the same unit; the results are unpredictable. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. Note that the ‘FGET’ intrinsic is provided for backwards compatibility with ‘g77’. GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability. See also *note Fortran 2003 status::. _Class_: Subroutine, function _Arguments_: UNIT The type shall be ‘INTEGER’. C The type shall be ‘CHARACTER’ and of default kind. STATUS (Optional) status flag of type ‘INTEGER’. Returns 0 on success, -1 on end-of-file and a system specific positive error code otherwise. _Example_: PROGRAM test_fgetc INTEGER :: fd = 42, status CHARACTER :: c OPEN(UNIT=fd, FILE="/etc/passwd", ACTION="READ", STATUS = "OLD") DO CALL fgetc(fd, c, status) IF (status /= 0) EXIT call fput(c) END DO CLOSE(UNIT=fd) END PROGRAM _Standard_: GNU extension _See also_: *note FGET::, *note FPUT::, *note FPUTC::  File: gfortran.info, Node: FINDLOC, Next: FLOOR, Prev: FGETC, Up: Intrinsic Procedures 8.108 ‘FINDLOC’ -- Search an array for a value ============================================== _Synopsis_: ‘RESULT = FINDLOC(ARRAY, VALUE, DIM [, MASK] [,KIND] [,BACK])’ ‘RESULT = FINDLOC(ARRAY, VALUE, [, MASK] [,KIND] [,BACK])’ _Description_: Determines the location of the element in the array with the value given in the VALUE argument, or, if the DIM argument is supplied, determines the locations of the elements equal to the VALUE argument element along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is ‘.TRUE.’ are considered. If more than one element in the array has the value VALUE, the location returned is that of the first such element in array element order if the BACK is not present or if it is ‘.FALSE.’. If BACK is true, the location returned is that of the last such element. If the array has zero size, or all of the elements of MASK are ‘.FALSE.’, then the result is an array of zeroes. Similarly, if DIM is supplied and all of the elements of MASK along a given row are zero, the result value for that row is zero. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of intrinsic type. VALUE A scalar of intrinsic type that is in type conformance with ARRAY. DIM (Optional) Shall be a scalar of type ‘INTEGER’, with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument. MASK (Optional) Shall be of type ‘LOGICAL’, and conformable with ARRAY. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. BACK (Optional) A scalar of type ‘LOGICAL’. _Notes_: ARRAY can also be ‘UNSIGNED’. _Return value_: If DIM is absent, the result is a rank-one array with a length equal to the rank of ARRAY. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the DIM dimension removed. If DIM is present and ARRAY has a rank of one, the result is a scalar. If the optional argument KIND is present, the result is an integer of kind KIND, otherwise it is of default kind. _Standard_: Fortran 2008 and later _See also_: *note MAXLOC::, *note MINLOC::  File: gfortran.info, Node: FLOOR, Next: FLUSH, Prev: FINDLOC, Up: Intrinsic Procedures 8.109 ‘FLOOR’ -- Integer floor function ======================================= _Synopsis_: ‘RESULT = FLOOR(A [, KIND])’ _Description_: ‘FLOOR(A)’ returns the greatest integer less than or equal to A. _Class_: Elemental function _Arguments_: A The type shall be ‘REAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER(KIND)’ if KIND is present and of default-kind ‘INTEGER’ otherwise. _Example_: program test_floor real :: x = 63.29 real :: y = -63.59 print *, floor(x) ! returns 63 print *, floor(y) ! returns -64 end program test_floor _Standard_: Fortran 95 and later _See also_: *note CEILING::, *note NINT::  File: gfortran.info, Node: FLUSH, Next: FNUM, Prev: FLOOR, Up: Intrinsic Procedures 8.110 ‘FLUSH’ -- Flush I/O unit(s) ================================== _Synopsis_: ‘CALL FLUSH(UNIT)’ _Description_: Flushes Fortran unit(s) currently open for output. Without the optional argument, all units are flushed, otherwise just the unit specified. _Class_: Subroutine _Arguments_: UNIT (Optional) The type shall be ‘INTEGER’. _Notes_: Beginning with the Fortran 2003 standard, there is a ‘FLUSH’ statement that should be preferred over the ‘FLUSH’ intrinsic. The ‘FLUSH’ intrinsic and the Fortran 2003 ‘FLUSH’ statement have identical effect: they flush the runtime library's I/O buffer so that the data becomes visible to other processes. This does not guarantee that the data is committed to disk. On POSIX systems, you can request that all data is transferred to the storage device by calling the ‘fsync’ function, with the POSIX file descriptor of the I/O unit as argument (retrieved with GNU intrinsic ‘FNUM’). The following example shows how: ! Declare the interface for POSIX fsync function interface function fsync (fd) bind(c,name="fsync") use iso_c_binding, only: c_int integer(c_int), value :: fd integer(c_int) :: fsync end function fsync end interface ! Variable declaration integer :: ret ! Opening unit 10 open (10,file="foo") ! ... ! Perform I/O on unit 10 ! ... ! Flush and sync flush(10) ret = fsync(fnum(10)) ! Handle possible error if (ret /= 0) stop "Error calling FSYNC" _Standard_: GNU extension  File: gfortran.info, Node: FNUM, Next: FPUT, Prev: FLUSH, Up: Intrinsic Procedures 8.111 ‘FNUM’ -- File number function ==================================== _Synopsis_: ‘RESULT = FNUM(UNIT)’ _Description_: ‘FNUM(UNIT)’ returns the POSIX file descriptor number corresponding to the open Fortran I/O unit ‘UNIT’. _Class_: Function _Arguments_: UNIT The type shall be ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’ _Example_: program test_fnum integer :: i open (unit=10, status = "scratch") i = fnum(10) print *, i close (10) end program test_fnum _Standard_: GNU extension  File: gfortran.info, Node: FPUT, Next: FPUTC, Prev: FNUM, Up: Intrinsic Procedures 8.112 ‘FPUT’ -- Write a single character in stream mode to stdout ================================================================= _Synopsis_: ‘CALL FPUT(C [, STATUS])’ ‘STATUS = FPUT(C)’ _Description_: Write a single character in stream mode to stdout by bypassing normal formatted output. Stream I/O should not be mixed with normal record-oriented (formatted or unformatted) I/O on the same unit; the results are unpredictable. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. Note that the ‘FGET’ intrinsic is provided for backwards compatibility with ‘g77’. GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability. See also *note Fortran 2003 status::. _Class_: Subroutine, function _Arguments_: C The type shall be ‘CHARACTER’ and of default kind. STATUS (Optional) status flag of type ‘INTEGER’. Returns 0 on success, -1 on end-of-file and a system specific positive error code otherwise. _Example_: PROGRAM test_fput CHARACTER(len=10) :: str = "gfortran" INTEGER :: i DO i = 1, len_trim(str) CALL fput(str(i:i)) END DO END PROGRAM _Standard_: GNU extension _See also_: *note FPUTC::, *note FGET::, *note FGETC::  File: gfortran.info, Node: FPUTC, Next: FRACTION, Prev: FPUT, Up: Intrinsic Procedures 8.113 ‘FPUTC’ -- Write a single character in stream mode ======================================================== _Synopsis_: ‘CALL FPUTC(UNIT, C [, STATUS])’ ‘STATUS = FPUTC(UNIT, C)’ _Description_: Write a single character in stream mode by bypassing normal formatted output. Stream I/O should not be mixed with normal record-oriented (formatted or unformatted) I/O on the same unit; the results are unpredictable. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. Note that the ‘FGET’ intrinsic is provided for backwards compatibility with ‘g77’. GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability. See also *note Fortran 2003 status::. _Class_: Subroutine, function _Arguments_: UNIT The type shall be ‘INTEGER’. C The type shall be ‘CHARACTER’ and of default kind. STATUS (Optional) status flag of type ‘INTEGER’. Returns 0 on success, -1 on end-of-file and a system specific positive error code otherwise. _Example_: PROGRAM test_fputc CHARACTER(len=10) :: str = "gfortran" INTEGER :: fd = 42, i OPEN(UNIT = fd, FILE = "out", ACTION = "WRITE", STATUS="NEW") DO i = 1, len_trim(str) CALL fputc(fd, str(i:i)) END DO CLOSE(fd) END PROGRAM _Standard_: GNU extension _See also_: *note FPUT::, *note FGET::, *note FGETC::  File: gfortran.info, Node: FRACTION, Next: FREE, Prev: FPUTC, Up: Intrinsic Procedures 8.114 ‘FRACTION’ -- Fractional part of the model representation =============================================================== _Synopsis_: ‘Y = FRACTION(X)’ _Description_: ‘FRACTION(X)’ returns the fractional part of the model representation of ‘X’. _Class_: Elemental function _Arguments_: X The type of the argument shall be a ‘REAL’. _Return value_: The return value is of the same type and kind as the argument. The fractional part of the model representation of ‘X’ is returned; it is ‘X * RADIX(X)**(-EXPONENT(X))’. _Example_: program test_fraction real :: x x = 178.1387e-4 print *, fraction(x), x * radix(x)**(-exponent(x)) end program test_fraction _Standard_: Fortran 90 and later  File: gfortran.info, Node: FREE, Next: FSEEK, Prev: FRACTION, Up: Intrinsic Procedures 8.115 ‘FREE’ -- Frees memory ============================ _Synopsis_: ‘CALL FREE(PTR)’ _Description_: Frees memory previously allocated by ‘MALLOC’. The ‘FREE’ intrinsic is an extension intended to be used with Cray pointers, and is provided in GNU Fortran to allow user to compile legacy code. For new code using Fortran 95 pointers, the memory de-allocation intrinsic is ‘DEALLOCATE’. _Class_: Subroutine _Arguments_: PTR The type shall be ‘INTEGER’. It represents the location of the memory that should be de-allocated. _Return value_: None _Example_: See ‘MALLOC’ for an example. _Standard_: GNU extension _See also_: *note MALLOC::  File: gfortran.info, Node: FSEEK, Next: FSTAT, Prev: FREE, Up: Intrinsic Procedures 8.116 ‘FSEEK’ -- Low level file positioning subroutine ====================================================== _Synopsis_: ‘CALL FSEEK(UNIT, OFFSET, WHENCE[, STATUS])’ _Description_: Moves UNIT to the specified OFFSET. If WHENCE is set to 0, the OFFSET is taken as an absolute value ‘SEEK_SET’, if set to 1, OFFSET is taken to be relative to the current position ‘SEEK_CUR’, and if set to 2 relative to the end of the file ‘SEEK_END’. On error, STATUS is set to a nonzero value. If STATUS the seek fails silently. This intrinsic routine is not fully backwards compatible with ‘g77’. In ‘g77’, the ‘FSEEK’ takes a statement label instead of a STATUS variable. If FSEEK is used in old code, change CALL FSEEK(UNIT, OFFSET, WHENCE, *label) to INTEGER :: status CALL FSEEK(UNIT, OFFSET, WHENCE, status) IF (status /= 0) GOTO label Please note that GNU Fortran provides the Fortran 2003 Stream facility. Programmers should consider the use of new stream IO feature in new code for future portability. See also *note Fortran 2003 status::. _Class_: Subroutine _Arguments_: UNIT Shall be a scalar of type ‘INTEGER’. OFFSET Shall be a scalar of type ‘INTEGER’. WHENCE Shall be a scalar of type ‘INTEGER’. Its value shall be either 0, 1 or 2. STATUS (Optional) shall be a scalar of type ‘INTEGER(4)’. _Example_: PROGRAM test_fseek INTEGER, PARAMETER :: SEEK_SET = 0, SEEK_CUR = 1, SEEK_END = 2 INTEGER :: fd, offset, ierr ierr = 0 offset = 5 fd = 10 OPEN(UNIT=fd, FILE="fseek.test") CALL FSEEK(fd, offset, SEEK_SET, ierr) ! move to OFFSET print *, FTELL(fd), ierr CALL FSEEK(fd, 0, SEEK_END, ierr) ! move to end print *, FTELL(fd), ierr CALL FSEEK(fd, 0, SEEK_SET, ierr) ! move to beginning print *, FTELL(fd), ierr CLOSE(UNIT=fd) END PROGRAM _Standard_: GNU extension _See also_: *note FTELL::  File: gfortran.info, Node: FSTAT, Next: FTELL, Prev: FSEEK, Up: Intrinsic Procedures 8.117 ‘FSTAT’ -- Get file status ================================ _Synopsis_: ‘CALL FSTAT(UNIT, VALUES [, STATUS])’ ‘STATUS = FSTAT(UNIT, VALUES)’ _Description_: ‘FSTAT’ is identical to *note STAT::, except that information about an already opened file is obtained. The elements in ‘VALUES’ are the same as described by *note STAT::. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: UNIT An open I/O unit number of type ‘INTEGER’. VALUES The type shall be ‘INTEGER(4), DIMENSION(13)’. STATUS (Optional) status flag of type ‘INTEGER(4)’. Returns 0 on success and a system specific error code otherwise. _Example_: See *note STAT:: for an example. _Standard_: GNU extension _See also_: To stat a link: *note LSTAT:: To stat a file: *note STAT::  File: gfortran.info, Node: FTELL, Next: GAMMA, Prev: FSTAT, Up: Intrinsic Procedures 8.118 ‘FTELL’ -- Current stream position ======================================== _Synopsis_: ‘CALL FTELL(UNIT, OFFSET)’ ‘OFFSET = FTELL(UNIT)’ _Description_: Retrieves the current position within an open file. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: OFFSET Shall of type ‘INTEGER’. UNIT Shall of type ‘INTEGER’. _Return value_: In either syntax, OFFSET is set to the current offset of unit number UNIT, or to -1 if the unit is not currently open. _Example_: PROGRAM test_ftell INTEGER :: i OPEN(10, FILE="temp.dat") CALL ftell(10,i) WRITE(*,*) i END PROGRAM _Standard_: GNU extension _See also_: *note FSEEK::  File: gfortran.info, Node: GAMMA, Next: GERROR, Prev: FTELL, Up: Intrinsic Procedures 8.119 ‘GAMMA’ -- Gamma function =============================== _Synopsis_: ‘X = GAMMA(X)’ _Description_: ‘GAMMA(X)’ computes Gamma (\Gamma) of X. For positive, integer values of X the Gamma function simplifies to the factorial function \Gamma(x)=(x-1)!. _Class_: Elemental function _Arguments_: X Shall be of type ‘REAL’ and neither zero nor a negative integer. _Return value_: The return value is of type ‘REAL’ of the same kind as X. _Example_: program test_gamma real :: x = 1.0 x = gamma(x) ! returns 1.0 end program test_gamma _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DGAMMA(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later _See also_: Logarithm of the Gamma function: *note LOG_GAMMA::  File: gfortran.info, Node: GERROR, Next: GETARG, Prev: GAMMA, Up: Intrinsic Procedures 8.120 ‘GERROR’ -- Get last system error message =============================================== _Synopsis_: ‘CALL GERROR(RESULT)’ _Description_: Returns the system error message corresponding to the last system error. This resembles the functionality of ‘strerror(3)’ in C. _Class_: Subroutine _Arguments_: RESULT Shall be of type ‘CHARACTER’ and of default kind. _Example_: PROGRAM test_gerror CHARACTER(len=100) :: msg CALL gerror(msg) WRITE(*,*) msg END PROGRAM _Standard_: GNU extension _See also_: *note IERRNO::, *note PERROR::  File: gfortran.info, Node: GETARG, Next: GET_COMMAND, Prev: GERROR, Up: Intrinsic Procedures 8.121 ‘GETARG’ -- Get command line arguments ============================================ _Synopsis_: ‘CALL GETARG(POS, VALUE)’ _Description_: Retrieve the POS-th argument that was passed on the command line when the containing program was invoked. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note GET_COMMAND_ARGUMENT:: intrinsic defined by the Fortran 2003 standard. _Class_: Subroutine _Arguments_: POS Shall be of type ‘INTEGER’ and not wider than the default integer kind; POS \geq 0 VALUE Shall be of type ‘CHARACTER’ and of default kind. _Return value_: After ‘GETARG’ returns, the VALUE argument holds the POSth command line argument. If VALUE cannot hold the argument, it is truncated to fit the length of VALUE. If there are less than POS arguments specified at the command line, VALUE is filled with blanks. If POS = 0, VALUE is set to the name of the program (on systems that support this feature). _Example_: PROGRAM test_getarg INTEGER :: i CHARACTER(len=32) :: arg DO i = 1, iargc() CALL getarg(i, arg) WRITE (*,*) arg END DO END PROGRAM _Standard_: GNU extension _See also_: GNU Fortran 77 compatibility function: *note IARGC:: Fortran 2003 functions and subroutines: *note GET_COMMAND::, *note GET_COMMAND_ARGUMENT::, *note COMMAND_ARGUMENT_COUNT::  File: gfortran.info, Node: GET_COMMAND, Next: GET_COMMAND_ARGUMENT, Prev: GETARG, Up: Intrinsic Procedures 8.122 ‘GET_COMMAND’ -- Get the entire command line ================================================== _Synopsis_: ‘CALL GET_COMMAND([COMMAND, LENGTH, STATUS])’ _Description_: Retrieve the entire command line that was used to invoke the program. _Class_: Subroutine _Arguments_: COMMAND (Optional) shall be of type ‘CHARACTER’ and of default kind. LENGTH (Optional) Shall be of type ‘INTEGER’ and of default kind. STATUS (Optional) Shall be of type ‘INTEGER’ and of default kind. _Return value_: If COMMAND is present, stores the entire command line that was used to invoke the program in COMMAND. If LENGTH is present, it is assigned the length of the command line. If STATUS is present, it is assigned 0 upon success of the command, -1 if COMMAND is too short to store the command line, or a positive value in case of an error. _Example_: PROGRAM test_get_command CHARACTER(len=255) :: cmd CALL get_command(cmd) WRITE (*,*) TRIM(cmd) END PROGRAM _Standard_: Fortran 2003 and later _See also_: *note GET_COMMAND_ARGUMENT::, *note COMMAND_ARGUMENT_COUNT::  File: gfortran.info, Node: GET_COMMAND_ARGUMENT, Next: GETCWD, Prev: GET_COMMAND, Up: Intrinsic Procedures 8.123 ‘GET_COMMAND_ARGUMENT’ -- Get command line arguments ========================================================== _Synopsis_: ‘CALL GET_COMMAND_ARGUMENT(NUMBER [, VALUE, LENGTH, STATUS])’ _Description_: Retrieve the NUMBER-th argument that was passed on the command line when the containing program was invoked. _Class_: Subroutine _Arguments_: NUMBER Shall be a scalar of type ‘INTEGER’ and of default kind, NUMBER \geq 0 VALUE (Optional) Shall be a scalar of type ‘CHARACTER’ and of default kind. LENGTH (Optional) Shall be a scalar of type ‘INTEGER’ and of default kind. STATUS (Optional) Shall be a scalar of type ‘INTEGER’ and of default kind. _Return value_: After ‘GET_COMMAND_ARGUMENT’ returns, the VALUE argument holds the NUMBER-th command line argument. If VALUE cannot hold the argument, it is truncated to fit the length of VALUE. If there are less than NUMBER arguments specified at the command line, VALUE is filled with blanks. If NUMBER = 0, VALUE is set to the name of the program (on systems that support this feature). The LENGTH argument contains the length of the NUMBER-th command line argument. If the argument retrieval fails, STATUS is a positive number; if VALUE contains a truncated command line argument, STATUS is -1; and otherwise the STATUS is zero. _Example_: PROGRAM test_get_command_argument INTEGER :: i CHARACTER(len=32) :: arg i = 0 DO CALL get_command_argument(i, arg) IF (LEN_TRIM(arg) == 0) EXIT WRITE (*,*) TRIM(arg) i = i+1 END DO END PROGRAM _Standard_: Fortran 2003 and later _See also_: *note GET_COMMAND::, *note COMMAND_ARGUMENT_COUNT::  File: gfortran.info, Node: GETCWD, Next: GETENV, Prev: GET_COMMAND_ARGUMENT, Up: Intrinsic Procedures 8.124 ‘GETCWD’ -- Get current working directory =============================================== _Synopsis_: ‘CALL GETCWD(C [, STATUS])’ ‘STATUS = GETCWD(C)’ _Description_: Get current working directory. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: C The type shall be ‘CHARACTER’ and of default kind. STATUS (Optional) status flag. Returns 0 on success, a system specific and nonzero error code otherwise. _Example_: PROGRAM test_getcwd CHARACTER(len=255) :: cwd CALL getcwd(cwd) WRITE(*,*) TRIM(cwd) END PROGRAM _Standard_: GNU extension _See also_: *note CHDIR::  File: gfortran.info, Node: GETENV, Next: GET_ENVIRONMENT_VARIABLE, Prev: GETCWD, Up: Intrinsic Procedures 8.125 ‘GETENV’ -- Get an environmental variable =============================================== _Synopsis_: ‘CALL GETENV(NAME, VALUE)’ _Description_: Get the VALUE of the environmental variable NAME. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note GET_ENVIRONMENT_VARIABLE:: intrinsic defined by the Fortran 2003 standard. Note that ‘GETENV’ need not be thread-safe. It is the responsibility of the user to ensure that the environment is not being updated concurrently with a call to the ‘GETENV’ intrinsic. _Class_: Subroutine _Arguments_: NAME Shall be of type ‘CHARACTER’ and of default kind. VALUE Shall be of type ‘CHARACTER’ and of default kind. _Return value_: Stores the value of NAME in VALUE. If VALUE is not large enough to hold the data, it is truncated. If NAME is not set, VALUE is filled with blanks. _Example_: PROGRAM test_getenv CHARACTER(len=255) :: homedir CALL getenv("HOME", homedir) WRITE (*,*) TRIM(homedir) END PROGRAM _Standard_: GNU extension _See also_: *note GET_ENVIRONMENT_VARIABLE::  File: gfortran.info, Node: GET_ENVIRONMENT_VARIABLE, Next: GETGID, Prev: GETENV, Up: Intrinsic Procedures 8.126 ‘GET_ENVIRONMENT_VARIABLE’ -- Get an environmental variable ================================================================= _Synopsis_: ‘CALL GET_ENVIRONMENT_VARIABLE(NAME[, VALUE, LENGTH, STATUS, TRIM_NAME)’ _Description_: Get the VALUE of the environmental variable NAME. Note that ‘GET_ENVIRONMENT_VARIABLE’ need not be thread-safe. It is the responsibility of the user to ensure that the environment is not being updated concurrently with a call to the ‘GET_ENVIRONMENT_VARIABLE’ intrinsic. _Class_: Subroutine _Arguments_: NAME Shall be a scalar of type ‘CHARACTER’ and of default kind. VALUE (Optional) Shall be a scalar of type ‘CHARACTER’ and of default kind. LENGTH (Optional) Shall be a scalar of type ‘INTEGER’ and of default kind. STATUS (Optional) Shall be a scalar of type ‘INTEGER’ and of default kind. TRIM_NAME (Optional) Shall be a scalar of type ‘LOGICAL’ and of default kind. _Return value_: Stores the value of NAME in VALUE. If VALUE is not large enough to hold the data, it is truncated. If NAME is not set, VALUE is filled with blanks. Argument LENGTH contains the length needed for storing the environment variable NAME or zero if it is not present. STATUS is -1 if VALUE is present but too short for the environment variable; it is 1 if the environment variable does not exist and 2 if the processor does not support environment variables; in all other cases STATUS is zero. If TRIM_NAME is present with the value ‘.FALSE.’, the trailing blanks in NAME are significant; otherwise they are not part of the environment variable name. _Example_: PROGRAM test_getenv CHARACTER(len=255) :: homedir CALL get_environment_variable("HOME", homedir) WRITE (*,*) TRIM(homedir) END PROGRAM _Standard_: Fortran 2003 and later  File: gfortran.info, Node: GETGID, Next: GETLOG, Prev: GET_ENVIRONMENT_VARIABLE, Up: Intrinsic Procedures 8.127 ‘GETGID’ -- Group ID function =================================== _Synopsis_: ‘RESULT = GETGID()’ _Description_: Returns the numerical group ID of the current process. _Class_: Function _Return value_: The return value of ‘GETGID’ is an ‘INTEGER’ of the default kind. _Example_: See ‘GETPID’ for an example. _Standard_: GNU extension _See also_: *note GETPID::, *note GETUID::  File: gfortran.info, Node: GETLOG, Next: GETPID, Prev: GETGID, Up: Intrinsic Procedures 8.128 ‘GETLOG’ -- Get login name ================================ _Synopsis_: ‘CALL GETLOG(C)’ _Description_: Gets the username under which the program is running. _Class_: Subroutine _Arguments_: C Shall be of type ‘CHARACTER’ and of default kind. _Return value_: Stores the current user name in C. (On systems where POSIX functions ‘geteuid’ and ‘getpwuid’ are not available, and the ‘getlogin’ function is not implemented either, this returns a blank string.) _Example_: PROGRAM TEST_GETLOG CHARACTER(32) :: login CALL GETLOG(login) WRITE(*,*) login END PROGRAM _Standard_: GNU extension _See also_: *note GETUID::  File: gfortran.info, Node: GETPID, Next: GETUID, Prev: GETLOG, Up: Intrinsic Procedures 8.129 ‘GETPID’ -- Process ID function ===================================== _Synopsis_: ‘RESULT = GETPID()’ _Description_: Returns the numerical process identifier of the current process. _Class_: Function _Return value_: The return value of ‘GETPID’ is an ‘INTEGER’ of the default kind. _Example_: program info print *, "The current process ID is ", getpid() print *, "Your numerical user ID is ", getuid() print *, "Your numerical group ID is ", getgid() end program info _Standard_: GNU extension _See also_: *note GETGID::, *note GETUID::  File: gfortran.info, Node: GETUID, Next: GMTIME, Prev: GETPID, Up: Intrinsic Procedures 8.130 ‘GETUID’ -- User ID function ================================== _Synopsis_: ‘RESULT = GETUID()’ _Description_: Returns the numerical user ID of the current process. _Class_: Function _Return value_: The return value of ‘GETUID’ is an ‘INTEGER’ of the default kind. _Example_: See ‘GETPID’ for an example. _Standard_: GNU extension _See also_: *note GETPID::, *note GETLOG::  File: gfortran.info, Node: GMTIME, Next: HOSTNM, Prev: GETUID, Up: Intrinsic Procedures 8.131 ‘GMTIME’ -- Convert time to GMT info ========================================== _Synopsis_: ‘CALL GMTIME(TIME, VALUES)’ _Description_: Given a system time value TIME (as provided by the *note TIME:: intrinsic), fills VALUES with values extracted from it appropriate to the UTC time zone (Universal Coordinated Time, also known in some countries as GMT, Greenwich Mean Time), using ‘gmtime(3)’. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95 standard. _Class_: Subroutine _Arguments_: TIME An ‘INTEGER’ scalar expression corresponding to a system time, with ‘INTENT(IN)’. VALUES A default ‘INTEGER’ array with 9 elements, with ‘INTENT(OUT)’. _Return value_: The elements of VALUES are assigned as follows: 1. Seconds after the minute, range 0-59 or 0-61 to allow for leap seconds 2. Minutes after the hour, range 0-59 3. Hours past midnight, range 0-23 4. Day of month, range 1-31 5. Number of months since January, range 0-11 6. Years since 1900 7. Number of days since Sunday, range 0-6 8. Days since January 1, range 0-365 9. Daylight savings indicator: positive if daylight savings is in effect, zero if not, and negative if the information is not available. _Standard_: GNU extension _See also_: *note DATE_AND_TIME::, *note CTIME::, *note LTIME::, *note TIME::, *note TIME8::  File: gfortran.info, Node: HOSTNM, Next: HUGE, Prev: GMTIME, Up: Intrinsic Procedures 8.132 ‘HOSTNM’ -- Get system host name ====================================== _Synopsis_: ‘CALL HOSTNM(C [, STATUS])’ ‘STATUS = HOSTNM(NAME)’ _Description_: Retrieves the host name of the system on which the program is running. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: C Shall of type ‘CHARACTER’ and of default kind. STATUS (Optional) status flag of type ‘INTEGER’. Returns 0 on success, or a system specific error code otherwise. _Return value_: In either syntax, NAME is set to the current hostname if it can be obtained, or to a blank string otherwise. _Standard_: GNU extension  File: gfortran.info, Node: HUGE, Next: HYPOT, Prev: HOSTNM, Up: Intrinsic Procedures 8.133 ‘HUGE’ -- Largest number of a kind ======================================== _Synopsis_: ‘RESULT = HUGE(X)’ _Description_: ‘HUGE(X)’ returns the largest number that is not an infinity in the model of the type of ‘X’. _Class_: Inquiry function _Arguments_: X Shall be of type ‘REAL’, ‘INTEGER’ or ‘UNSIGNED’. _Return value_: The return value is of the same type and kind as X _Example_: program test_huge_tiny print *, huge(0), huge(0.0), huge(0.0d0) print *, tiny(0.0), tiny(0.0d0) end program test_huge_tiny _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: HYPOT, Next: IACHAR, Prev: HUGE, Up: Intrinsic Procedures 8.134 ‘HYPOT’ -- Euclidean distance function ============================================ _Synopsis_: ‘RESULT = HYPOT(X, Y)’ _Description_: ‘HYPOT(X,Y)’ is the Euclidean distance function. It is equal to \sqrt{X^2 + Y^2}, without undue underflow or overflow. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. Y The type and kind type parameter shall be the same as X. _Return value_: The return value has the same type and kind type parameter as X. _Example_: program test_hypot real(4) :: x = 1.e0_4, y = 0.5e0_4 x = hypot(x,y) end program test_hypot _Standard_: Fortran 2008 and later  File: gfortran.info, Node: IACHAR, Next: IALL, Prev: HYPOT, Up: Intrinsic Procedures 8.135 ‘IACHAR’ -- Code in ASCII collating sequence ================================================== _Synopsis_: ‘RESULT = IACHAR(C [, KIND])’ _Description_: ‘IACHAR(C)’ returns the code for the ASCII character in the first character position of ‘C’. _Class_: Elemental function _Arguments_: C Shall be a scalar ‘CHARACTER’, with ‘INTENT(IN)’ KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Example_: program test_iachar integer i i = iachar(' ') end program test_iachar _Notes_: See *note ICHAR:: for a discussion of converting between numerical values and formatted string representations. _Standard_: Fortran 95 and later, with KIND argument Fortran 2003 and later _See also_: *note ACHAR::, *note CHAR::, *note ICHAR::  File: gfortran.info, Node: IALL, Next: IAND, Prev: IACHAR, Up: Intrinsic Procedures 8.136 ‘IALL’ -- Bitwise AND of array elements ============================================= _Synopsis_: ‘RESULT = IALL(ARRAY[, MASK])’ ‘RESULT = IALL(ARRAY, DIM[, MASK])’ _Description_: Reduces with bitwise AND the elements of ARRAY along dimension DIM if the corresponding element in MASK is ‘TRUE’. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’ or ‘UNSIGNED’ DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of ARRAY. MASK (Optional) shall be of type ‘LOGICAL’ and either be a scalar or an array of the same shape as ARRAY. _Return value_: The result is of the same type as ARRAY. If DIM is absent, a scalar with the bitwise ALL of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned. _Example_: PROGRAM test_iall INTEGER(1) :: a(2) a(1) = b'00100100' a(2) = b'01101010' ! prints 00100000 PRINT '(b8.8)', IALL(a) END PROGRAM _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IANY::, *note IPARITY::, *note IAND::  File: gfortran.info, Node: IAND, Next: IANY, Prev: IALL, Up: Intrinsic Procedures 8.137 ‘IAND’ -- Bitwise logical and =================================== _Synopsis_: ‘RESULT = IAND(I, J)’ _Description_: Bitwise logical ‘AND’. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’, ‘UNSIGNED’ or a boz-literal-constant. J The type shall be the same type as I with the same kind type parameter or a boz-literal-constant. I and J shall not both be boz-literal-constants. _Return value_: The return type is with the kind type parameter of the arguments. A boz-literal-constant is converted to an ‘INTEGER’ or ‘UNSIGNED’ with the kind type parameter of the other argument as-if a call to *note INT:: or *note UINT::, respectively, occurred. _Example_: PROGRAM test_iand INTEGER :: a, b DATA a / Z'F' /, b / Z'3' / WRITE (*,*) IAND(a, b) END PROGRAM _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘IAND(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BIAND(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIAND(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIAND(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIAND(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, with boz-literal-constant Fortran 2008 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IOR::, *note IEOR::, *note IBITS::, *note IBSET::, *note IBCLR::, *note NOT::  File: gfortran.info, Node: IANY, Next: IARGC, Prev: IAND, Up: Intrinsic Procedures 8.138 ‘IANY’ -- Bitwise OR of array elements ============================================ _Synopsis_: ‘RESULT = IANY(ARRAY[, MASK])’ ‘RESULT = IANY(ARRAY, DIM[, MASK])’ _Description_: Reduces with bitwise OR (inclusive or) the elements of ARRAY along dimension DIM if the corresponding element in MASK is ‘TRUE’. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’ or ‘UNSIGNED’ DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of ARRAY. MASK (Optional) shall be of type ‘LOGICAL’ and either be a scalar or an array of the same shape as ARRAY. _Return value_: The result is of the same type as ARRAY. If DIM is absent, a scalar with the bitwise OR of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned. _Example_: PROGRAM test_iany INTEGER(1) :: a(2) a(1) = b'00100100' a(2) = b'01101010' ! prints 01101110 PRINT '(b8.8)', IANY(a) END PROGRAM _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IPARITY::, *note IALL::, *note IOR::  File: gfortran.info, Node: IARGC, Next: IBCLR, Prev: IANY, Up: Intrinsic Procedures 8.139 ‘IARGC’ -- Get the number of command line arguments ========================================================= _Synopsis_: ‘RESULT = IARGC()’ _Description_: ‘IARGC’ returns the number of arguments passed on the command line when the containing program was invoked. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note COMMAND_ARGUMENT_COUNT:: intrinsic defined by the Fortran 2003 standard. _Class_: Function _Arguments_: None _Return value_: The number of command line arguments, type ‘INTEGER(4)’. _Example_: See *note GETARG:: _Standard_: GNU extension _See also_: GNU Fortran 77 compatibility subroutine: *note GETARG:: Fortran 2003 functions and subroutines: *note GET_COMMAND::, *note GET_COMMAND_ARGUMENT::, *note COMMAND_ARGUMENT_COUNT::  File: gfortran.info, Node: IBCLR, Next: IBITS, Prev: IARGC, Up: Intrinsic Procedures 8.140 ‘IBCLR’ -- Clear bit ========================== _Synopsis_: ‘RESULT = IBCLR(I, POS)’ _Description_: ‘IBCLR’ returns the value of I with the bit at position POS set to zero. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. POS The type shall be ‘INTEGER’. _Return value_: The return value is of the same type as I. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘IBCLR(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BBCLR(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIBCLR(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIBCLR(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIBCLR(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IBITS::, *note IBSET::, *note IAND::, *note IOR::, *note IEOR::, *note MVBITS::  File: gfortran.info, Node: IBITS, Next: IBSET, Prev: IBCLR, Up: Intrinsic Procedures 8.141 ‘IBITS’ -- Bit extraction =============================== _Synopsis_: ‘RESULT = IBITS(I, POS, LEN)’ _Description_: ‘IBITS’ extracts a field of length LEN from I, starting from bit position POS and extending left for LEN bits. The result is right-justified and the remaining bits are zeroed. The value of ‘POS+LEN’ must be less than or equal to the value ‘BIT_SIZE(I)’. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. POS The type shall be ‘INTEGER’. LEN The type shall be ‘INTEGER’. _Return value_: The return value is of type as I. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘IBITS(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BBITS(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIBITS(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIBITS(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIBITS(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note BIT_SIZE::, *note IBCLR::, *note IBSET::, *note IAND::, *note IOR::, *note IEOR::  File: gfortran.info, Node: IBSET, Next: ICHAR, Prev: IBITS, Up: Intrinsic Procedures 8.142 ‘IBSET’ -- Set bit ======================== _Synopsis_: ‘RESULT = IBSET(I, POS)’ _Description_: ‘IBSET’ returns the value of I with the bit at position POS set to one. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. POS The type shall be ‘INTEGER’. _Return value_: The return value is of the same type as I. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘IBSET(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BBSET(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIBSET(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIBSET(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIBSET(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IBCLR::, *note IBITS::, *note IAND::, *note IOR::, *note IEOR::, *note MVBITS::  File: gfortran.info, Node: ICHAR, Next: IDATE, Prev: IBSET, Up: Intrinsic Procedures 8.143 ‘ICHAR’ -- Character-to-integer conversion function ========================================================= _Synopsis_: ‘RESULT = ICHAR(C [, KIND])’ _Description_: ‘ICHAR(C)’ returns the code for the character in the first character position of ‘C’ in the system's native character set. The correspondence between characters and their codes is not necessarily the same across different GNU Fortran implementations. _Class_: Elemental function _Arguments_: C Shall be a scalar ‘CHARACTER’, with ‘INTENT(IN)’ KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Example_: program test_ichar integer i i = ichar(' ') end program test_ichar _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ICHAR(C)’ ‘CHARACTER C’ ‘INTEGER(4)’ Fortran 77 and later _Notes_: No intrinsic exists to convert between a numeric value and a formatted character string representation - for instance, given the ‘CHARACTER’ value ‘'154'’, obtaining an ‘INTEGER’ or ‘REAL’ value with the value 154, or vice versa. Instead, this functionality is provided by internal-file I/O, as in the following example: program read_val integer value character(len=10) string, string2 string = '154' ! Convert a string to a numeric value read (string,'(I10)') value print *, value ! Convert a value to a formatted string write (string2,'(I10)') value print *, string2 end program read_val _Standard_: Fortran 77 and later, with KIND argument Fortran 2003 and later _See also_: *note ACHAR::, *note CHAR::, *note IACHAR::  File: gfortran.info, Node: IDATE, Next: IEOR, Prev: ICHAR, Up: Intrinsic Procedures 8.144 ‘IDATE’ -- Get current local time subroutine (day/month/year) =================================================================== _Synopsis_: ‘CALL IDATE(VALUES)’ _Description_: ‘IDATE(VALUES)’ Fills VALUES with the numerical values at the current local time. The day (in the range 1-31), month (in the range 1-12), and year appear in elements 1, 2, and 3 of VALUES, respectively. The year has four significant digits. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95 standard. _Class_: Subroutine _Arguments_: VALUES The type shall be ‘INTEGER, DIMENSION(3)’ and the kind shall be the default integer kind. _Return value_: Does not return anything. _Example_: program test_idate integer, dimension(3) :: tarray call idate(tarray) print *, tarray(1) print *, tarray(2) print *, tarray(3) end program test_idate _Standard_: GNU extension _See also_: *note DATE_AND_TIME::  File: gfortran.info, Node: IEOR, Next: IERRNO, Prev: IDATE, Up: Intrinsic Procedures 8.145 ‘IEOR’ -- Bitwise logical exclusive or ============================================ _Synopsis_: ‘RESULT = IEOR(I, J)’ _Description_: ‘IEOR’ returns the bitwise Boolean exclusive-OR of I and J. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’, ‘UNSIGNED’ or a boz-literal-constant. J The type shall be the same type as I with the same kind type parameter or a boz-literal-constant. I and J shall not both be boz-literal-constants. _Return value_: The return type is with the kind type parameter of the arguments. A boz-literal-constant is converted to an ‘INTEGER’ or ‘UNSIGNED’ with the kind type parameter of the other argument as-if a call to *note INT:: or *note UINT::, respectively, occurred. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘IEOR(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BIEOR(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIEOR(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIEOR(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIEOR(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, with boz-literal-constant Fortran 2008 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IOR::, *note IAND::, *note IBITS::, *note IBSET::, *note IBCLR::, *note NOT::  File: gfortran.info, Node: IERRNO, Next: IMAGE_INDEX, Prev: IEOR, Up: Intrinsic Procedures 8.146 ‘IERRNO’ -- Get the last system error number ================================================== _Synopsis_: ‘RESULT = IERRNO()’ _Description_: Returns the last system error number, as given by the C ‘errno’ variable. _Class_: Function _Arguments_: None _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Standard_: GNU extension _See also_: *note PERROR::  File: gfortran.info, Node: IMAGE_INDEX, Next: INDEX intrinsic, Prev: IERRNO, Up: Intrinsic Procedures 8.147 ‘IMAGE_INDEX’ -- Function that converts a cosubscript to an image index ============================================================================= _Synopsis_: ‘RESULT = IMAGE_INDEX(COARRAY, SUB)’ _Description_: Returns the image index belonging to a cosubscript. _Class_: Inquiry function. _Arguments_: COARRAY Coarray of any type. SUB default integer rank-1 array of a size equal to the corank of COARRAY. _Return value_: Scalar default integer with the value of the image index that corresponds to the cosubscripts. For invalid cosubscripts the result is zero. _Example_: INTEGER :: array[2,-1:4,8,*] ! Writes 28 (or 0 if there are fewer than 28 images) WRITE (*,*) IMAGE_INDEX (array, [2,0,3,1]) _Standard_: Fortran 2008 and later _See also_: *note THIS_IMAGE::, *note NUM_IMAGES::  File: gfortran.info, Node: INDEX intrinsic, Next: INT, Prev: IMAGE_INDEX, Up: Intrinsic Procedures 8.148 ‘INDEX’ -- Position of a substring within a string ======================================================== _Synopsis_: ‘RESULT = INDEX(STRING, SUBSTRING [, BACK [, KIND]])’ _Description_: Returns the position of the start of the first occurrence of string SUBSTRING as a substring in STRING, counting from one. If SUBSTRING is not present in STRING, zero is returned. If the BACK argument is present and true, the return value is the start of the last occurrence rather than the first. _Class_: Elemental function _Arguments_: STRING Shall be a scalar ‘CHARACTER’, with ‘INTENT(IN)’ SUBSTRING Shall be a scalar ‘CHARACTER’, with ‘INTENT(IN)’ BACK (Optional) Shall be a scalar ‘LOGICAL’, with ‘INTENT(IN)’ KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Specific names_: Name Argument Return Standard type -------------------------------------------------------------------------- ‘INDEX(STRING,SUBSTRING)’ ‘CHARACTER’ ‘INTEGER(4)’ Fortran 77 and later _Standard_: Fortran 77 and later, with KIND argument Fortran 2003 and later _See also_: *note SCAN::, *note VERIFY::  File: gfortran.info, Node: INT, Next: INT2, Prev: INDEX intrinsic, Up: Intrinsic Procedures 8.149 ‘INT’ -- Convert to integer type ====================================== _Synopsis_: ‘RESULT = INT(A [, KIND))’ _Description_: Convert to integer type _Class_: Elemental function, extension for ‘UNSIGNED’ (*note Unsigned integers::). _Arguments_: A Shall be of type ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’ or a boz-literal-constant. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: These functions return a ‘INTEGER’ variable or array under the following rules: (A) If A is of type ‘INTEGER’, ‘INT(A) = A’ (B) If A is of type ‘REAL’ and |A| < 1, ‘INT(A)’ equals ‘0’. If |A| \geq 1, then ‘INT(A)’ is the integer whose magnitude is the largest integer that does not exceed the magnitude of A and whose sign is the same as the sign of A. (C) If A is of type ‘COMPLEX’, rule B is applied to the real part of A. (D) If A is of type ‘UNSIGNED’ and 0 \leq A \leq ‘HUGE(A)’, ‘INT(A) = A’. Outside that range, the result is interpreted using two's complement. _Example_: program test_int integer :: i = 42 complex :: z = (-3.7, 1.0) print *, int(i) print *, int(z), int(z,8) end program _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘INT(A)’ ‘REAL(4) A’ ‘INTEGER’ Fortran 77 and later ‘IFIX(A)’ ‘REAL(4) A’ ‘INTEGER’ Fortran 77 and later ‘IDINT(A)’ ‘REAL(8) A’ ‘INTEGER’ Fortran 77 and later _Standard_: Fortran 77 and later, with boz-literal-constant Fortran 2008 and later.  File: gfortran.info, Node: INT2, Next: INT8, Prev: INT, Up: Intrinsic Procedures 8.150 ‘INT2’ -- Convert to 16-bit integer type ============================================== _Synopsis_: ‘RESULT = INT2(A)’ _Description_: Convert to a ‘KIND=2’ integer type. This is equivalent to the standard ‘INT’ intrinsic with an optional argument of ‘KIND=2’, and is only included for backwards compatibility. _Class_: Elemental function _Arguments_: A Shall be of type ‘INTEGER’, ‘REAL’, or ‘COMPLEX’. _Return value_: The return value is a ‘INTEGER(2)’ variable. _Standard_: GNU extension _See also_: *note INT::, *note INT8::  File: gfortran.info, Node: INT8, Next: IOR, Prev: INT2, Up: Intrinsic Procedures 8.151 ‘INT8’ -- Convert to 64-bit integer type ============================================== _Synopsis_: ‘RESULT = INT8(A)’ _Description_: Convert to a ‘KIND=8’ integer type. This is equivalent to the standard ‘INT’ intrinsic with an optional argument of ‘KIND=8’, and is only included for backwards compatibility. _Class_: Elemental function _Arguments_: A Shall be of type ‘INTEGER’, ‘REAL’, or ‘COMPLEX’. _Return value_: The return value is a ‘INTEGER(8)’ variable. _Standard_: GNU extension _See also_: *note INT::, *note INT2::  File: gfortran.info, Node: IOR, Next: IPARITY, Prev: INT8, Up: Intrinsic Procedures 8.152 ‘IOR’ -- Bitwise logical or ================================= _Synopsis_: ‘RESULT = IOR(I, J)’ _Description_: ‘IOR’ returns the bitwise Boolean inclusive-OR of I and J. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’, ‘UNSIGNED’ or a boz-literal-constant. J The type shall be the same type as I with the same kind type parameter or a boz-literal-constant. I and J shall not both be boz-literal-constants. _Return value_: The return type is ‘INTEGER’ with the kind type parameter of the arguments. A boz-literal-constant is converted to an ‘INTEGER’ or ‘UNSIGNED’ with the kind type parameter of the other argument as-if a call to *note INT:: or *note UINT::, respectively, occurred. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘IOR(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BIOR(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IIOR(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JIOR(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KIOR(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, with boz-literal-constant Fortran 2008 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IEOR::, *note IAND::, *note IBITS::, *note IBSET::, *note IBCLR::, *note NOT::  File: gfortran.info, Node: IPARITY, Next: IRAND, Prev: IOR, Up: Intrinsic Procedures 8.153 ‘IPARITY’ -- Bitwise XOR of array elements ================================================ _Synopsis_: ‘RESULT = IPARITY(ARRAY[, MASK])’ ‘RESULT = IPARITY(ARRAY, DIM[, MASK])’ _Description_: Reduces with bitwise XOR (exclusive or) the elements of ARRAY along dimension DIM if the corresponding element in MASK is ‘TRUE’. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’ or ‘UNSIGNED’. DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of ARRAY. MASK (Optional) shall be of type ‘LOGICAL’ and either be a scalar or an array of the same shape as ARRAY. _Return value_: The result is of the same type as ARRAY. If DIM is absent, a scalar with the bitwise XOR of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned. _Example_: PROGRAM test_iparity INTEGER(1) :: a(2) a(1) = int(b'00100100', 1) a(2) = int(b'01101010', 1) ! prints 01001110 PRINT '(b8.8)', IPARITY(a) END PROGRAM _Standard_: Fortran 2008 and later. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IANY::, *note IALL::, *note IEOR::, *note PARITY::  File: gfortran.info, Node: IRAND, Next: IS_CONTIGUOUS, Prev: IPARITY, Up: Intrinsic Procedures 8.154 ‘IRAND’ -- Integer pseudo-random number ============================================= _Synopsis_: ‘RESULT = IRAND(I)’ _Description_: ‘IRAND(FLAG)’ returns a pseudo-random number from a uniform distribution between 0 and a system-dependent limit (which is in most cases 2147483647). If FLAG is 0, the next number in the current sequence is returned; if FLAG is 1, the generator is restarted by ‘CALL SRAND(0)’; if FLAG has any other value, it is used as a new seed with ‘SRAND’. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. It implements a simple modulo generator as provided by ‘g77’. For new code, one should consider the use of *note RANDOM_NUMBER:: as it implements a superior algorithm. _Class_: Function _Arguments_: I Shall be a scalar ‘INTEGER’ of kind 4. _Return value_: The return value is of ‘INTEGER(kind=4)’ type. _Example_: program test_irand integer,parameter :: seed = 86456 call srand(seed) print *, irand(), irand(), irand(), irand() print *, irand(seed), irand(), irand(), irand() end program test_irand _Standard_: GNU extension  File: gfortran.info, Node: IS_CONTIGUOUS, Next: IS_IOSTAT_END, Prev: IRAND, Up: Intrinsic Procedures 8.155 ‘IS_CONTIGUOUS’ -- Test whether an array is contiguous ============================================================ _Synopsis_: ‘RESULT = IS_CONTIGUOUS(ARRAY)’ _Description_: ‘IS_CONTIGUOUS’ tests whether an array is contiguous. _Class_: Inquiry function _Arguments_: ARRAY Shall be an array of any type. _Return value_: Returns a ‘LOGICAL’ of the default kind, which is ‘.TRUE.’ if ARRAY is contiguous and false otherwise. _Example_: program test integer :: a(10) a = [1,2,3,4,5,6,7,8,9,10] call sub (a) ! every element, is contiguous call sub (a(::2)) ! every other element, is noncontiguous contains subroutine sub (x) integer :: x(:) if (is_contiguous (x)) then write (*,*) 'X is contiguous' else write (*,*) 'X is not contiguous' end if end subroutine sub end program test _Standard_: Fortran 2008 and later  File: gfortran.info, Node: IS_IOSTAT_END, Next: IS_IOSTAT_EOR, Prev: IS_CONTIGUOUS, Up: Intrinsic Procedures 8.156 ‘IS_IOSTAT_END’ -- Test for end-of-file value =================================================== _Synopsis_: ‘RESULT = IS_IOSTAT_END(I)’ _Description_: ‘IS_IOSTAT_END’ tests whether an variable has the value of the I/O status "end of file". The function is equivalent to comparing the variable with the ‘IOSTAT_END’ parameter of the intrinsic module ‘ISO_FORTRAN_ENV’. _Class_: Elemental function _Arguments_: I Shall be of the type ‘INTEGER’. _Return value_: Returns a ‘LOGICAL’ of the default kind, which is ‘.TRUE.’ if I has the value that indicates an end of file condition for ‘IOSTAT=’ specifiers, and is ‘.FALSE.’ otherwise. _Example_: PROGRAM iostat IMPLICIT NONE INTEGER :: stat, i OPEN(88, FILE='test.dat') READ(88, *, IOSTAT=stat) i IF(IS_IOSTAT_END(stat)) STOP 'END OF FILE' END PROGRAM _Standard_: Fortran 2003 and later  File: gfortran.info, Node: IS_IOSTAT_EOR, Next: ISATTY, Prev: IS_IOSTAT_END, Up: Intrinsic Procedures 8.157 ‘IS_IOSTAT_EOR’ -- Test for end-of-record value ===================================================== _Synopsis_: ‘RESULT = IS_IOSTAT_EOR(I)’ _Description_: ‘IS_IOSTAT_EOR’ tests whether an variable has the value of the I/O status "end of record". The function is equivalent to comparing the variable with the ‘IOSTAT_EOR’ parameter of the intrinsic module ‘ISO_FORTRAN_ENV’. _Class_: Elemental function _Arguments_: I Shall be of the type ‘INTEGER’. _Return value_: Returns a ‘LOGICAL’ of the default kind, which is ‘.TRUE.’ if I has the value that indicates an end of file condition for ‘IOSTAT=’ specifiers, and is ‘.FALSE.’ otherwise. _Example_: PROGRAM iostat IMPLICIT NONE INTEGER :: stat, i(50) OPEN(88, FILE='test.dat', FORM='UNFORMATTED') READ(88, IOSTAT=stat) i IF(IS_IOSTAT_EOR(stat)) STOP 'END OF RECORD' END PROGRAM _Standard_: Fortran 2003 and later  File: gfortran.info, Node: ISATTY, Next: ISHFT, Prev: IS_IOSTAT_EOR, Up: Intrinsic Procedures 8.158 ‘ISATTY’ -- Whether a unit is a terminal device ===================================================== _Synopsis_: ‘RESULT = ISATTY(UNIT)’ _Description_: Determine whether a unit is connected to a terminal device. _Class_: Function _Arguments_: UNIT Shall be a scalar ‘INTEGER’. _Return value_: Returns ‘.TRUE.’ if the UNIT is connected to a terminal device, ‘.FALSE.’ otherwise. _Example_: PROGRAM test_isatty INTEGER(kind=1) :: unit DO unit = 1, 10 write(*,*) isatty(unit=unit) END DO END PROGRAM _Standard_: GNU extension _See also_: *note TTYNAM::  File: gfortran.info, Node: ISHFT, Next: ISHFTC, Prev: ISATTY, Up: Intrinsic Procedures 8.159 ‘ISHFT’ -- Shift bits =========================== _Synopsis_: ‘RESULT = ISHFT(I, SHIFT)’ _Description_: ‘ISHFT’ returns a value corresponding to I with all of the bits shifted SHIFT places. A value of SHIFT greater than zero corresponds to a left shift, a value of zero corresponds to no shift, and a value less than zero corresponds to a right shift. If the absolute value of SHIFT is greater than ‘BIT_SIZE(I)’, the value is undefined. Bits shifted out from the left end or right end are lost; zeros are shifted in from the opposite end. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. SHIFT The type shall be ‘INTEGER’. _Return value_: The return value is of type of I. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ISHFT(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BSHFT(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IISHFT(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JISHFT(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KISHFT(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note ISHFTC::  File: gfortran.info, Node: ISHFTC, Next: ISNAN, Prev: ISHFT, Up: Intrinsic Procedures 8.160 ‘ISHFTC’ -- Shift bits circularly ======================================= _Synopsis_: ‘RESULT = ISHFTC(I, SHIFT [, SIZE])’ _Description_: ‘ISHFTC’ returns a value corresponding to I with the rightmost SIZE bits shifted circularly SHIFT places; that is, bits shifted out one end are shifted into the opposite end. A value of SHIFT greater than zero corresponds to a left shift, a value of zero corresponds to no shift, and a value less than zero corresponds to a right shift. The absolute value of SHIFT must be less than SIZE. If the SIZE argument is omitted, it is taken to be equivalent to ‘BIT_SIZE(I)’. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. SHIFT The type shall be ‘INTEGER’. SIZE (Optional) The type shall be ‘INTEGER’; the value must be greater than zero and less than or equal to ‘BIT_SIZE(I)’. _Return value_: The return value is of the same type as I. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ISHFTC(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BSHFTC(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IISHFTC(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JISHFTC(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KISHFTC(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note ISHFT::  File: gfortran.info, Node: ISNAN, Next: ITIME, Prev: ISHFTC, Up: Intrinsic Procedures 8.161 ‘ISNAN’ -- Test for a NaN =============================== _Synopsis_: ‘ISNAN(X)’ _Description_: ‘ISNAN’ tests whether a floating-point value is an IEEE Not-a-Number (NaN). _Class_: Elemental function _Arguments_: X Variable of the type ‘REAL’. _Return value_: Returns a default-kind ‘LOGICAL’. The returned value is ‘TRUE’ if X is a NaN and ‘FALSE’ otherwise. _Example_: program test_nan implicit none real :: x x = -1.0 x = sqrt(x) if (isnan(x)) stop '"x" is a NaN' end program test_nan _Standard_: GNU extension  File: gfortran.info, Node: ITIME, Next: KILL, Prev: ISNAN, Up: Intrinsic Procedures 8.162 ‘ITIME’ -- Get current local time subroutine (hour/minutes/seconds) ========================================================================= _Synopsis_: ‘CALL ITIME(VALUES)’ _Description_: ‘ITIME(VALUES)’ Fills VALUES with the numerical values at the current local time. The hour (in the range 1-24), minute (in the range 1-60), and seconds (in the range 1-60) appear in elements 1, 2, and 3 of VALUES, respectively. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95 standard. _Class_: Subroutine _Arguments_: VALUES The type shall be ‘INTEGER, DIMENSION(3)’ and the kind shall be the default integer kind. _Return value_: Does not return anything. _Example_: program test_itime integer, dimension(3) :: tarray call itime(tarray) print *, tarray(1) print *, tarray(2) print *, tarray(3) end program test_itime _Standard_: GNU extension _See also_: *note DATE_AND_TIME::  File: gfortran.info, Node: KILL, Next: KIND, Prev: ITIME, Up: Intrinsic Procedures 8.163 ‘KILL’ -- Send a signal to a process ========================================== _Synopsis_: ‘CALL KILL(PID, SIG [, STATUS])’ ‘STATUS = KILL(PID, SIG)’ _Description_: Sends the signal specified by SIG to the process PID. See ‘kill(2)’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: PID Shall be a scalar ‘INTEGER’ with ‘INTENT(IN)’. SIG Shall be a scalar ‘INTEGER’ with ‘INTENT(IN)’. STATUS [Subroutine](Optional) Shall be a scalar ‘INTEGER’. Returns 0 on success; otherwise a system-specific error code is returned. STATUS [Function] The kind type parameter is that of ‘pid’. Returns 0 on success; otherwise a system-specific error code is returned. _Standard_: GNU extension _See also_: *note ABORT::, *note EXIT::  File: gfortran.info, Node: KIND, Next: LBOUND, Prev: KILL, Up: Intrinsic Procedures 8.164 ‘KIND’ -- Kind of an entity ================================= _Synopsis_: ‘K = KIND(X)’ _Description_: ‘KIND(X)’ returns the kind value of the entity X. _Class_: Inquiry function _Arguments_: X Shall be of type ‘LOGICAL’, ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘CHARACTER’. It may be scalar or array valued. _Return value_: The return value is a scalar of type ‘INTEGER’ and of the default integer kind. _Example_: program test_kind integer,parameter :: kc = kind(' ') integer,parameter :: kl = kind(.true.) print *, "The default character kind is ", kc print *, "The default logical kind is ", kl end program test_kind _Standard_: Fortran 95 and later  File: gfortran.info, Node: LBOUND, Next: LCOBOUND, Prev: KIND, Up: Intrinsic Procedures 8.165 ‘LBOUND’ -- Lower dimension bounds of an array ==================================================== _Synopsis_: ‘RESULT = LBOUND(ARRAY [, DIM [, KIND]])’ _Description_: Returns the lower bounds of an array, or a single lower bound along the DIM dimension. _Class_: Inquiry function _Arguments_: ARRAY Shall be an array, of any type. DIM (Optional) Shall be a scalar ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is absent, the result is an array of the lower bounds of ARRAY. If DIM is present, the result is a scalar corresponding to the lower bound of the array along that dimension. If ARRAY is an expression rather than a whole array or array structure component, or if it has a zero extent along the relevant dimension, the lower bound is taken to be 1. _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note UBOUND::, *note LCOBOUND::  File: gfortran.info, Node: LCOBOUND, Next: LEADZ, Prev: LBOUND, Up: Intrinsic Procedures 8.166 ‘LCOBOUND’ -- Lower codimension bounds of an array ======================================================== _Synopsis_: ‘RESULT = LCOBOUND(COARRAY [, DIM [, KIND]])’ _Description_: Returns the lower bounds of a coarray, or a single lower cobound along the DIM codimension. _Class_: Inquiry function _Arguments_: ARRAY Shall be an coarray, of any type. DIM (Optional) Shall be a scalar ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is absent, the result is an array of the lower cobounds of COARRAY. If DIM is present, the result is a scalar corresponding to the lower cobound of the array along that codimension. _Standard_: Fortran 2008 and later _See also_: *note UCOBOUND::, *note LBOUND::  File: gfortran.info, Node: LEADZ, Next: LEN, Prev: LCOBOUND, Up: Intrinsic Procedures 8.167 ‘LEADZ’ -- Number of leading zero bits of an integer ========================================================== _Synopsis_: ‘RESULT = LEADZ(I)’ _Description_: ‘LEADZ’ returns the number of leading zero bits of an integer. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’. _Return value_: The type of the return value is the default ‘INTEGER’. If all the bits of ‘I’ are zero, the result value is ‘BIT_SIZE(I)’. _Example_: PROGRAM test_leadz WRITE (*,*) BIT_SIZE(1) ! prints 32 WRITE (*,*) LEADZ(1) ! prints 31 END PROGRAM _Standard_: Fortran 2008 and later _See also_: *note BIT_SIZE::, *note TRAILZ::, *note POPCNT::, *note POPPAR::  File: gfortran.info, Node: LEN, Next: LEN_TRIM, Prev: LEADZ, Up: Intrinsic Procedures 8.168 ‘LEN’ -- Length of a character entity =========================================== _Synopsis_: ‘L = LEN(STRING [, KIND])’ _Description_: Returns the length of a character string. If STRING is an array, the length of an element of STRING is returned. Note that STRING need not be defined when this intrinsic is invoked, since only the length, not the content, of STRING is needed. _Class_: Inquiry function _Arguments_: STRING Shall be a scalar or array of type ‘CHARACTER’, with ‘INTENT(IN)’ KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘LEN(STRING)’ ‘CHARACTER’ ‘INTEGER’ Fortran 77 and later _Standard_: Fortran 77 and later, with KIND argument Fortran 2003 and later _See also_: *note LEN_TRIM::, *note ADJUSTL::, *note ADJUSTR::  File: gfortran.info, Node: LEN_TRIM, Next: LGE, Prev: LEN, Up: Intrinsic Procedures 8.169 ‘LEN_TRIM’ -- Length of a character entity without trailing blank characters ================================================================================== _Synopsis_: ‘RESULT = LEN_TRIM(STRING [, KIND])’ _Description_: Returns the length of a character string, ignoring any trailing blanks. _Class_: Elemental function _Arguments_: STRING Shall be a scalar of type ‘CHARACTER’, with ‘INTENT(IN)’ KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note LEN::, *note ADJUSTL::, *note ADJUSTR::  File: gfortran.info, Node: LGE, Next: LGT, Prev: LEN_TRIM, Up: Intrinsic Procedures 8.170 ‘LGE’ -- Lexical greater than or equal ============================================ _Synopsis_: ‘RESULT = LGE(STRING_A, STRING_B)’ _Description_: Determines whether one string is lexically greater than or equal to another string, where the two strings are interpreted as containing ASCII character codes. If the String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer. In general, the lexical comparison intrinsics ‘LGE’, ‘LGT’, ‘LLE’, and ‘LLT’ differ from the corresponding intrinsic operators ‘.GE.’, ‘.GT.’, ‘.LE.’, and ‘.LT.’, in that the latter use the processor's character ordering (which is not ASCII on some targets), whereas the former always use the ASCII ordering. _Class_: Elemental function _Arguments_: STRING_A Shall be of default ‘CHARACTER’ type. STRING_B Shall be of default ‘CHARACTER’ type. _Return value_: Returns ‘.TRUE.’ if ‘STRING_A >= STRING_B’, and ‘.FALSE.’ otherwise, based on the ASCII ordering. _Specific names_: Name Argument Return Standard type -------------------------------------------------------------------------- ‘LGE(STRING_A,STRING_B)’ ‘CHARACTER’ ‘LOGICAL’ Fortran 77 and later _Standard_: Fortran 77 and later _See also_: *note LGT::, *note LLE::, *note LLT::  File: gfortran.info, Node: LGT, Next: LINK, Prev: LGE, Up: Intrinsic Procedures 8.171 ‘LGT’ -- Lexical greater than =================================== _Synopsis_: ‘RESULT = LGT(STRING_A, STRING_B)’ _Description_: Determines whether one string is lexically greater than another string, where the two strings are interpreted as containing ASCII character codes. If the String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer. In general, the lexical comparison intrinsics ‘LGE’, ‘LGT’, ‘LLE’, and ‘LLT’ differ from the corresponding intrinsic operators ‘.GE.’, ‘.GT.’, ‘.LE.’, and ‘.LT.’, in that the latter use the processor's character ordering (which is not ASCII on some targets), whereas the former always use the ASCII ordering. _Class_: Elemental function _Arguments_: STRING_A Shall be of default ‘CHARACTER’ type. STRING_B Shall be of default ‘CHARACTER’ type. _Return value_: Returns ‘.TRUE.’ if ‘STRING_A > STRING_B’, and ‘.FALSE.’ otherwise, based on the ASCII ordering. _Specific names_: Name Argument Return Standard type -------------------------------------------------------------------------- ‘LGT(STRING_A,STRING_B)’ ‘CHARACTER’ ‘LOGICAL’ Fortran 77 and later _Standard_: Fortran 77 and later _See also_: *note LGE::, *note LLE::, *note LLT::  File: gfortran.info, Node: LINK, Next: LLE, Prev: LGT, Up: Intrinsic Procedures 8.172 ‘LINK’ -- Create a hard link ================================== _Synopsis_: ‘CALL LINK(PATH1, PATH2 [, STATUS])’ ‘STATUS = LINK(PATH1, PATH2)’ _Description_: Makes a (hard) link from file PATH1 to PATH2. A null character (‘CHAR(0)’) can be used to mark the end of the names in PATH1 and PATH2; otherwise, trailing blanks in the file names are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see ‘link(2)’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: PATH1 Shall be of default ‘CHARACTER’ type. PATH2 Shall be of default ‘CHARACTER’ type. STATUS (Optional) Shall be of default ‘INTEGER’ type. _Standard_: GNU extension _See also_: *note SYMLNK::, *note UNLINK::  File: gfortran.info, Node: LLE, Next: LLT, Prev: LINK, Up: Intrinsic Procedures 8.173 ‘LLE’ -- Lexical less than or equal ========================================= _Synopsis_: ‘RESULT = LLE(STRING_A, STRING_B)’ _Description_: Determines whether one string is lexically less than or equal to another string, where the two strings are interpreted as containing ASCII character codes. If the String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer. In general, the lexical comparison intrinsics ‘LGE’, ‘LGT’, ‘LLE’, and ‘LLT’ differ from the corresponding intrinsic operators ‘.GE.’, ‘.GT.’, ‘.LE.’, and ‘.LT.’, in that the latter use the processor's character ordering (which is not ASCII on some targets), whereas the former always use the ASCII ordering. _Class_: Elemental function _Arguments_: STRING_A Shall be of default ‘CHARACTER’ type. STRING_B Shall be of default ‘CHARACTER’ type. _Return value_: Returns ‘.TRUE.’ if ‘STRING_A <= STRING_B’, and ‘.FALSE.’ otherwise, based on the ASCII ordering. _Specific names_: Name Argument Return Standard type -------------------------------------------------------------------------- ‘LLE(STRING_A,STRING_B)’ ‘CHARACTER’ ‘LOGICAL’ Fortran 77 and later _Standard_: Fortran 77 and later _See also_: *note LGE::, *note LGT::, *note LLT::  File: gfortran.info, Node: LLT, Next: LNBLNK, Prev: LLE, Up: Intrinsic Procedures 8.174 ‘LLT’ -- Lexical less than ================================ _Synopsis_: ‘RESULT = LLT(STRING_A, STRING_B)’ _Description_: Determines whether one string is lexically less than another string, where the two strings are interpreted as containing ASCII character codes. If the String A and String B are not the same length, the shorter is compared as if spaces were appended to it to form a value that has the same length as the longer. In general, the lexical comparison intrinsics ‘LGE’, ‘LGT’, ‘LLE’, and ‘LLT’ differ from the corresponding intrinsic operators ‘.GE.’, ‘.GT.’, ‘.LE.’, and ‘.LT.’, in that the latter use the processor's character ordering (which is not ASCII on some targets), whereas the former always use the ASCII ordering. _Class_: Elemental function _Arguments_: STRING_A Shall be of default ‘CHARACTER’ type. STRING_B Shall be of default ‘CHARACTER’ type. _Return value_: Returns ‘.TRUE.’ if ‘STRING_A < STRING_B’, and ‘.FALSE.’ otherwise, based on the ASCII ordering. _Specific names_: Name Argument Return Standard type -------------------------------------------------------------------------- ‘LLT(STRING_A,STRING_B)’ ‘CHARACTER’ ‘LOGICAL’ Fortran 77 and later _Standard_: Fortran 77 and later _See also_: *note LGE::, *note LGT::, *note LLE::  File: gfortran.info, Node: LNBLNK, Next: LOC, Prev: LLT, Up: Intrinsic Procedures 8.175 ‘LNBLNK’ -- Index of the last non-blank character in a string =================================================================== _Synopsis_: ‘RESULT = LNBLNK(STRING)’ _Description_: Returns the length of a character string, ignoring any trailing blanks. This is identical to the standard ‘LEN_TRIM’ intrinsic, and is only included for backwards compatibility. _Class_: Elemental function _Arguments_: STRING Shall be a scalar of type ‘CHARACTER’, with ‘INTENT(IN)’ _Return value_: The return value is of ‘INTEGER(kind=4)’ type. _Standard_: GNU extension _See also_: *note INDEX intrinsic::, *note LEN_TRIM::  File: gfortran.info, Node: LOC, Next: LOG, Prev: LNBLNK, Up: Intrinsic Procedures 8.176 ‘LOC’ -- Returns the address of a variable ================================================ _Synopsis_: ‘RESULT = LOC(X)’ _Description_: ‘LOC(X)’ returns the address of X as an integer. _Class_: Inquiry function _Arguments_: X Variable of any type. _Return value_: The return value is of type ‘INTEGER’, with a ‘KIND’ corresponding to the size (in bytes) of a memory address on the target machine. _Example_: program test_loc integer :: i real :: r i = loc(r) print *, i end program test_loc _Standard_: GNU extension  File: gfortran.info, Node: LOG, Next: LOG10, Prev: LOC, Up: Intrinsic Procedures 8.177 ‘LOG’ -- Natural logarithm function ========================================= _Synopsis_: ‘RESULT = LOG(X)’ _Description_: ‘LOG(X)’ computes the natural logarithm of X, i.e. the logarithm to the base e. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value is of type ‘REAL’ or ‘COMPLEX’. The kind type parameter is the same as X. If X is ‘COMPLEX’, the imaginary part \omega is in the range -\pi < \omega \leq \pi. _Example_: program test_log real(8) :: x = 2.7182818284590451_8 complex :: z = (1.0, 2.0) x = log(x) ! yields (approximately) 1 z = log(z) end program test_log _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ALOG(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 or later ‘DLOG(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 or later ‘CLOG(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ Fortran 77 or later ‘ZLOG(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDLOG(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 77 and later, has GNU extensions  File: gfortran.info, Node: LOG10, Next: LOG_GAMMA, Prev: LOG, Up: Intrinsic Procedures 8.178 ‘LOG10’ -- Base 10 logarithm function =========================================== _Synopsis_: ‘RESULT = LOG10(X)’ _Description_: ‘LOG10(X)’ computes the base 10 logarithm of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value is of type ‘REAL’ or ‘COMPLEX’. The kind type parameter is the same as X. _Example_: program test_log10 real(8) :: x = 10.0_8 x = log10(x) end program test_log10 _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘ALOG10(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DLOG10(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later  File: gfortran.info, Node: LOG_GAMMA, Next: LOGICAL, Prev: LOG10, Up: Intrinsic Procedures 8.179 ‘LOG_GAMMA’ -- Logarithm of the Gamma function ==================================================== _Synopsis_: ‘X = LOG_GAMMA(X)’ _Description_: ‘LOG_GAMMA(X)’ computes the natural logarithm of the absolute value of the Gamma (\Gamma) function. _Class_: Elemental function _Arguments_: X Shall be of type ‘REAL’ and neither zero nor a negative integer. _Return value_: The return value is of type ‘REAL’ of the same kind as X. _Example_: program test_log_gamma real :: x = 1.0 x = lgamma(x) ! returns 0.0 end program test_log_gamma _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘LGAMMA(X)’ ‘REAL(4) X’ ‘REAL(4)’ GNU extension ‘ALGAMA(X)’ ‘REAL(4) X’ ‘REAL(4)’ GNU extension ‘DLGAMA(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2008 and later _See also_: Gamma function: *note GAMMA::  File: gfortran.info, Node: LOGICAL, Next: LSHIFT, Prev: LOG_GAMMA, Up: Intrinsic Procedures 8.180 ‘LOGICAL’ -- Convert to logical type ========================================== _Synopsis_: ‘RESULT = LOGICAL(L [, KIND])’ _Description_: Converts one kind of ‘LOGICAL’ variable to another. _Class_: Elemental function _Arguments_: L The type shall be ‘LOGICAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is a ‘LOGICAL’ value equal to L, with a kind corresponding to KIND, or of the default logical kind if KIND is not given. _Standard_: Fortran 90 and later _See also_: *note INT::, *note REAL::, *note CMPLX::  File: gfortran.info, Node: LSHIFT, Next: LSTAT, Prev: LOGICAL, Up: Intrinsic Procedures 8.181 ‘LSHIFT’ -- Left shift bits ================================= _Synopsis_: ‘RESULT = LSHIFT(I, SHIFT)’ _Description_: ‘LSHIFT’ returns a value corresponding to I with all of the bits shifted left by SHIFT places. SHIFT shall be nonnegative and less than or equal to ‘BIT_SIZE(I)’, otherwise the result value is undefined. Bits shifted out from the left end are lost; zeros are shifted in from the opposite end. This function has been superseded by the ‘ISHFT’ intrinsic, which is standard in Fortran 95 and later, and the ‘SHIFTL’ intrinsic, which is standard in Fortran 2008 and later. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’. SHIFT The type shall be ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’ and of the same kind as I. _Standard_: GNU extension _See also_: *note ISHFT::, *note ISHFTC::, *note RSHIFT::, *note SHIFTA::, *note SHIFTL::, *note SHIFTR::  File: gfortran.info, Node: LSTAT, Next: LTIME, Prev: LSHIFT, Up: Intrinsic Procedures 8.182 ‘LSTAT’ -- Get file status ================================ _Synopsis_: ‘CALL LSTAT(NAME, VALUES [, STATUS])’ ‘STATUS = LSTAT(NAME, VALUES)’ _Description_: ‘LSTAT’ is identical to *note STAT::, except that if path is a symbolic link, then the operation is performed on the link itself, not the file that it refers to. The elements in ‘VALUES’ are the same as described by *note STAT::. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: NAME The type shall be ‘CHARACTER’ of the default kind, a valid path within the file system. VALUES The type shall be ‘INTEGER(4), DIMENSION(13)’. STATUS (Optional) status flag of type ‘INTEGER(4)’. Returns 0 on success and a system specific error code otherwise. _Example_: See *note STAT:: for an example. _Standard_: GNU extension _See also_: To stat an open file: *note FSTAT:: To stat a file: *note STAT::  File: gfortran.info, Node: LTIME, Next: MALLOC, Prev: LSTAT, Up: Intrinsic Procedures 8.183 ‘LTIME’ -- Convert time to local time info ================================================ _Synopsis_: ‘CALL LTIME(TIME, VALUES)’ _Description_: Given a system time value TIME (as provided by the *note TIME:: intrinsic), fills VALUES with values extracted from it appropriate to the local time zone using ‘localtime(3)’. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. In new code, programmers should consider the use of the *note DATE_AND_TIME:: intrinsic defined by the Fortran 95 standard. _Class_: Subroutine _Arguments_: TIME An ‘INTEGER’ scalar expression corresponding to a system time, with ‘INTENT(IN)’. VALUES A default ‘INTEGER’ array with 9 elements, with ‘INTENT(OUT)’. _Return value_: The elements of VALUES are assigned as follows: 1. Seconds after the minute, range 0-59 or 0-61 to allow for leap seconds 2. Minutes after the hour, range 0-59 3. Hours past midnight, range 0-23 4. Day of month, range 1-31 5. Number of months since January, range 0-11 6. Years since 1900 7. Number of days since Sunday, range 0-6 8. Days since January 1, range 0-365 9. Daylight savings indicator: positive if daylight savings is in effect, zero if not, and negative if the information is not available. _Standard_: GNU extension _See also_: *note DATE_AND_TIME::, *note CTIME::, *note GMTIME::, *note TIME::, *note TIME8::  File: gfortran.info, Node: MALLOC, Next: MASKL, Prev: LTIME, Up: Intrinsic Procedures 8.184 ‘MALLOC’ -- Allocate dynamic memory ========================================= _Synopsis_: ‘PTR = MALLOC(SIZE)’ _Description_: ‘MALLOC(SIZE)’ allocates SIZE bytes of dynamic memory and returns the address of the allocated memory. The ‘MALLOC’ intrinsic is an extension intended to be used with Cray pointers, and is provided in GNU Fortran to allow the user to compile legacy code. For new code using Fortran 95 pointers, the memory allocation intrinsic is ‘ALLOCATE’. _Class_: Function _Arguments_: SIZE The type shall be ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER(K)’, with K such that variables of type ‘INTEGER(K)’ have the same size as C pointers (‘sizeof(void *)’). _Example_: The following example demonstrates the use of ‘MALLOC’ and ‘FREE’ with Cray pointers. program test_malloc implicit none integer i real*8 x(*), z pointer(ptr_x,x) ptr_x = malloc(20*8) do i = 1, 20 x(i) = sqrt(1.0d0 / i) end do z = 0 do i = 1, 20 z = z + x(i) print *, z end do call free(ptr_x) end program test_malloc _Standard_: GNU extension _See also_: *note FREE::  File: gfortran.info, Node: MASKL, Next: MASKR, Prev: MALLOC, Up: Intrinsic Procedures 8.185 ‘MASKL’ -- Left justified mask ==================================== _Synopsis_: ‘RESULT = MASKL(I[, KIND])’ _Description_: ‘MASKL(I[, KIND])’ has its leftmost I bits set to 1, and the remaining bits set to 0. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’. KIND Shall be a scalar constant expression of type ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’. If KIND is present, it specifies the kind value of the return type; otherwise, it is of the default integer kind. _Standard_: Fortran 2008 and later _See also_: *note MASKR::  File: gfortran.info, Node: MASKR, Next: MATMUL, Prev: MASKL, Up: Intrinsic Procedures 8.186 ‘MASKR’ -- Right justified mask ===================================== _Synopsis_: ‘RESULT = MASKR(I[, KIND])’ _Description_: ‘MASKL(I[, KIND])’ has its rightmost I bits set to 1, and the remaining bits set to 0. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’. KIND Shall be a scalar constant expression of type ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’. If KIND is present, it specifies the kind value of the return type; otherwise, it is of the default integer kind. _Standard_: Fortran 2008 and later _See also_: *note MASKL::  File: gfortran.info, Node: MATMUL, Next: MAX, Prev: MASKR, Up: Intrinsic Procedures 8.187 ‘MATMUL’ -- matrix multiplication ======================================= _Synopsis_: ‘RESULT = MATMUL(MATRIX_A, MATRIX_B)’ _Description_: Performs a matrix multiplication on numeric or logical arguments. _Class_: Transformational function _Arguments_: MATRIX_A An array of ‘INTEGER’, ‘REAL’, ‘COMPLEX’, ‘UNSIGNED’ or ‘LOGICAL’ type, with a rank of one or two. MATRIX_B An array of ‘INTEGER’, ‘REAL’, or ‘COMPLEX’ type if MATRIX_A is of ‘INTEGER’, ‘REAL’, or ‘COMPLEX’ type. Otherwise, if MATRIX_A is an array of ‘UNSIGNED’ or ‘LOGICAL’ type, the type shall be the same as that of MATRIX_A. The rank shall be one or two, and the first (or only) dimension of MATRIX_B shall be equal to the last (or only) dimension of MATRIX_A. MATRIX_A and MATRIX_B shall not both be rank one arrays. _Return value_: The matrix product of MATRIX_A and MATRIX_B. The type and kind of the result follow the usual type and kind promotion rules, as for the ‘*’ or ‘.AND.’ operators. _Standard_: Fortran 90 and later. Extension for‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: MAX, Next: MAXEXPONENT, Prev: MATMUL, Up: Intrinsic Procedures 8.188 ‘MAX’ -- Maximum value of an argument list ================================================ _Synopsis_: ‘RESULT = MAX(A1, A2 [, A3 [, ...]])’ _Description_: Returns the argument with the largest (most positive) value. _Class_: Elemental function _Arguments_: A1 The type shall be ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’. A2, A3, An expression of the same type and kind as A1. ... (As a GNU extension, arguments of different kinds are permitted.) _Return value_: The return value corresponds to the maximum value among the arguments, and has the same type and kind as the first argument. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘MAX0(A1)’ ‘INTEGER(4) A1’ ‘INTEGER(4)’ Fortran 77 and later ‘AMAX0(A1)’ ‘INTEGER(4) A1’ ‘REAL(MAX(X))’ Fortran 77 and later ‘MAX1(A1)’ ‘REAL A1’ ‘INT(MAX(X))’ Fortran 77 and later ‘AMAX1(A1)’ ‘REAL(4) A1’ ‘REAL(4)’ Fortran 77 and later ‘DMAX1(A1)’ ‘REAL(8) A1’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later. Extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note MAXLOC:: *note MAXVAL::, *note MIN::  File: gfortran.info, Node: MAXEXPONENT, Next: MAXLOC, Prev: MAX, Up: Intrinsic Procedures 8.189 ‘MAXEXPONENT’ -- Maximum exponent of a real kind ====================================================== _Synopsis_: ‘RESULT = MAXEXPONENT(X)’ _Description_: ‘MAXEXPONENT(X)’ returns the maximum exponent in the model of the type of ‘X’. _Class_: Inquiry function _Arguments_: X Shall be of type ‘REAL’. _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Example_: program exponents real(kind=4) :: x real(kind=8) :: y print *, minexponent(x), maxexponent(x) print *, minexponent(y), maxexponent(y) end program exponents _Standard_: Fortran 90 and later  File: gfortran.info, Node: MAXLOC, Next: MAXVAL, Prev: MAXEXPONENT, Up: Intrinsic Procedures 8.190 ‘MAXLOC’ -- Location of the maximum value within an array =============================================================== _Synopsis_: ‘RESULT = MAXLOC(ARRAY, DIM [, MASK] [,KIND] [,BACK])’ ‘RESULT = MAXLOC(ARRAY [, MASK] [,KIND] [,BACK])’ _Description_: Determines the location of the element in the array with the maximum value, or, if the DIM argument is supplied, determines the locations of the maximum element along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is ‘.TRUE.’ are considered. If more than one element in the array has the maximum value, the location returned is that of the first such element in array element order if the BACK is not present, or is false; if BACK is true, the location returned is that of the last such element. If the array has zero size, or all of the elements of MASK are ‘.FALSE.’, then the result is an array of zeroes. Similarly, if DIM is supplied and all of the elements of MASK along a given row are zero, the result value for that row is zero. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’, ‘REAL’, ‘UNSIGNED’ or ‘CHARACTER’. DIM (Optional) Shall be a scalar of type ‘INTEGER’, with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument. MASK Shall be of type ‘LOGICAL’, and conformable with ARRAY. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. BACK (Optional) A scalar of type ‘LOGICAL’. _Return value_: If DIM is absent, the result is a rank-one array with a length equal to the rank of ARRAY. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the DIM dimension removed. If DIM is present and ARRAY has a rank of one, the result is a scalar. If the optional argument KIND is present, the result is an integer of kind KIND, otherwise it is of default kind. _Standard_: Fortran 95 and later; ARRAY of ‘CHARACTER’ and the KIND argument are available in Fortran 2003 and later. The BACK argument is available in Fortran 2008 and later. Extension for‘UNSIGNED’ (*note Unsigned integers::). _See also_: *note FINDLOC::, *note MAX::, *note MAXVAL::  File: gfortran.info, Node: MAXVAL, Next: MCLOCK, Prev: MAXLOC, Up: Intrinsic Procedures 8.191 ‘MAXVAL’ -- Maximum value of an array =========================================== _Synopsis_: ‘RESULT = MAXVAL(ARRAY, DIM [, MASK])’ ‘RESULT = MAXVAL(ARRAY [, MASK])’ _Description_: Determines the maximum value of the elements in an array value, or, if the DIM argument is supplied, determines the maximum value along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is ‘.TRUE.’ are considered. If the array has zero size, or all of the elements of MASK are ‘.FALSE.’, then the result is ‘-HUGE(ARRAY)’ if ARRAY is of type ‘INTEGER’ or ‘REAL’, ‘0’ if it is type ‘UNSIGNED’. or a string of nulls if ARRAY is of character type. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’, ‘REAL’, ‘UNSIGNED’ or ‘CHARACTER’. DIM (Optional) Shall be a scalar of type ‘INTEGER’, with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument. MASK (Optional) Shall be of type ‘LOGICAL’, and conformable with ARRAY. _Return value_: If DIM is absent, or if ARRAY has a rank of one, the result is a scalar. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the DIM dimension removed. In all cases, the result is of the same type and kind as ARRAY. _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note MAX::, *note MAXLOC::  File: gfortran.info, Node: MCLOCK, Next: MCLOCK8, Prev: MAXVAL, Up: Intrinsic Procedures 8.192 ‘MCLOCK’ -- Time function =============================== _Synopsis_: ‘RESULT = MCLOCK()’ _Description_: Returns the number of clock ticks since the start of the process, based on the function ‘clock(3)’ in the C standard library. This intrinsic is not fully portable, such as to systems with 32-bit ‘INTEGER’ types but supporting times wider than 32 bits. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program. _Class_: Function _Return value_: The return value is a scalar of type ‘INTEGER(4)’, equal to the number of clock ticks since the start of the process, or ‘-1’ if the system does not support ‘clock(3)’. _Standard_: GNU extension _See also_: *note CTIME::, *note GMTIME::, *note LTIME::, *note MCLOCK::, *note TIME::  File: gfortran.info, Node: MCLOCK8, Next: MERGE, Prev: MCLOCK, Up: Intrinsic Procedures 8.193 ‘MCLOCK8’ -- Time function (64-bit) ========================================= _Synopsis_: ‘RESULT = MCLOCK8()’ _Description_: Returns the number of clock ticks since the start of the process, based on the function ‘clock(3)’ in the C standard library. _Warning:_ this intrinsic does not increase the range of the timing values over that returned by ‘clock(3)’. On a system with a 32-bit ‘clock(3)’, ‘MCLOCK8’ returns a 32-bit value, even though it is converted to a 64-bit ‘INTEGER(8)’ value. That means overflows of the 32-bit value can still occur. Therefore, the values returned by this intrinsic might be or become negative or numerically less than previous values during a single run of the compiled program. _Class_: Function _Return value_: The return value is a scalar of type ‘INTEGER(8)’, equal to the number of clock ticks since the start of the process, or ‘-1’ if the system does not support ‘clock(3)’. _Standard_: GNU extension _See also_: *note CTIME::, *note GMTIME::, *note LTIME::, *note MCLOCK::, *note TIME8::  File: gfortran.info, Node: MERGE, Next: MERGE_BITS, Prev: MCLOCK8, Up: Intrinsic Procedures 8.194 ‘MERGE’ -- Merge variables ================================ _Synopsis_: ‘RESULT = MERGE(TSOURCE, FSOURCE, MASK)’ _Description_: Select values from two arrays according to a logical mask. The result is equal to TSOURCE if MASK is ‘.TRUE.’, or equal to FSOURCE if it is ‘.FALSE.’. _Class_: Elemental function _Arguments_: TSOURCE May be of any type. FSOURCE Shall be of the same type and type parameters as TSOURCE. MASK Shall be of type ‘LOGICAL’. _Return value_: The result is of the same type and type parameters as TSOURCE. _Standard_: Fortran 90 and later  File: gfortran.info, Node: MERGE_BITS, Next: MIN, Prev: MERGE, Up: Intrinsic Procedures 8.195 ‘MERGE_BITS’ -- Merge of bits under mask ============================================== _Synopsis_: ‘RESULT = MERGE_BITS(I, J, MASK)’ _Description_: ‘MERGE_BITS(I, J, MASK)’ merges the bits of I and J as determined by the mask. The i-th bit of the result is equal to the i-th bit of I if the i-th bit of MASK is 1; it is equal to the i-th bit of J otherwise. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’, ‘UNSIGNED’ or a boz-literal-constant. I and J shall not both be boz-literal-constants. J The type shall be the same type as I with the same kind type parameter or a boz-literal-constant. MASK Shall be of the same type as I, J or a boz-literal-constant. _Return value_: The result is of the same type and kind as I. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: MIN, Next: MINEXPONENT, Prev: MERGE_BITS, Up: Intrinsic Procedures 8.196 ‘MIN’ -- Minimum value of an argument list ================================================ _Synopsis_: ‘RESULT = MIN(A1, A2 [, A3, ...])’ _Description_: Returns the argument with the smallest (most negative) value. _Class_: Elemental function _Arguments_: A1 The type shall be ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’. A2, A3, An expression of the same type and kind as A1. ... (As a GNU extension, arguments of different kinds are permitted.) _Return value_: The return value corresponds to the minimum value among the arguments, and has the same type and kind as the first argument. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘MIN0(A1)’ ‘INTEGER(4) A1’ ‘INTEGER(4)’ Fortran 77 and later ‘AMIN0(A1)’ ‘INTEGER(4) A1’ ‘REAL(4)’ Fortran 77 and later ‘MIN1(A1)’ ‘REAL A1’ ‘INTEGER(4)’ Fortran 77 and later ‘AMIN1(A1)’ ‘REAL(4) A1’ ‘REAL(4)’ Fortran 77 and later ‘DMIN1(A1)’ ‘REAL(8) A1’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note MAX::, *note MINLOC::, *note MINVAL::  File: gfortran.info, Node: MINEXPONENT, Next: MINLOC, Prev: MIN, Up: Intrinsic Procedures 8.197 ‘MINEXPONENT’ -- Minimum exponent of a real kind ====================================================== _Synopsis_: ‘RESULT = MINEXPONENT(X)’ _Description_: ‘MINEXPONENT(X)’ returns the minimum exponent in the model of the type of ‘X’. _Class_: Inquiry function _Arguments_: X Shall be of type ‘REAL’. _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Example_: See ‘MAXEXPONENT’ for an example. _Standard_: Fortran 90 and later  File: gfortran.info, Node: MINLOC, Next: MINVAL, Prev: MINEXPONENT, Up: Intrinsic Procedures 8.198 ‘MINLOC’ -- Location of the minimum value within an array =============================================================== _Synopsis_: ‘RESULT = MINLOC(ARRAY, DIM [, MASK] [,KIND] [,BACK])’ ‘RESULT = MINLOC(ARRAY [, MASK], [,KIND] [,BACK])’ _Description_: Determines the location of the element in the array with the minimum value, or, if the DIM argument is supplied, determines the locations of the minimum element along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is ‘.TRUE.’ are considered. If more than one element in the array has the minimum value, the location returned is that of the first such element in array element order if the BACK is not present, or is false; if BACK is true, the location returned is that of the last such element. If the array has zero size, or all of the elements of MASK are ‘.FALSE.’, then the result is an array of zeroes. Similarly, if DIM is supplied and all of the elements of MASK along a given row are zero, the result value for that row is zero. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’, ‘REAL’, ‘CHARACTER’ or ‘UNSIGNED’. DIM (Optional) Shall be a scalar of type ‘INTEGER’, with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument. MASK Shall be of type ‘LOGICAL’, and conformable with ARRAY. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. BACK (Optional) A scalar of type ‘LOGICAL’. _Return value_: If DIM is absent, the result is a rank-one array with a length equal to the rank of ARRAY. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the DIM dimension removed. If DIM is present and ARRAY has a rank of one, the result is a scalar. If the optional argument KIND is present, the result is an integer of kind KIND, otherwise it is of default kind. _Standard_: Fortran 90 and later; ARRAY of ‘CHARACTER’ and the KIND argument are available in Fortran 2003 and later. The BACK argument is available in Fortran 2008 and later. Extension for ‘UNSIGNED’ (*note Unsigned integers::). _See also_: *note FINDLOC::, *note MIN::, *note MINVAL::  File: gfortran.info, Node: MINVAL, Next: MOD, Prev: MINLOC, Up: Intrinsic Procedures 8.199 ‘MINVAL’ -- Minimum value of an array =========================================== _Synopsis_: ‘RESULT = MINVAL(ARRAY, DIM [, MASK])’ ‘RESULT = MINVAL(ARRAY [, MASK])’ _Description_: Determines the minimum value of the elements in an array value, or, if the DIM argument is supplied, determines the minimum value along each row of the array in the DIM direction. If MASK is present, only the elements for which MASK is ‘.TRUE.’ are considered. If the array has zero size, or all of the elements of MASK are ‘.FALSE.’, then the result is ‘HUGE(ARRAY)’ if ARRAY is numeric, or a string of ‘CHAR(255)’ characters if ARRAY is of character type. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’. DIM (Optional) Shall be a scalar of type ‘INTEGER’, with a value between one and the rank of ARRAY, inclusive. It may not be an optional dummy argument. MASK Shall be of type ‘LOGICAL’, and conformable with ARRAY. _Return value_: If DIM is absent, or if ARRAY has a rank of one, the result is a scalar. If DIM is present, the result is an array with a rank one less than the rank of ARRAY, and a size corresponding to the size of ARRAY with the DIM dimension removed. In all cases, the result is of the same type and kind as ARRAY. _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note MIN::, *note MINLOC::  File: gfortran.info, Node: MOD, Next: MODULO, Prev: MINVAL, Up: Intrinsic Procedures 8.200 ‘MOD’ -- Remainder function ================================= _Synopsis_: ‘RESULT = MOD(A, P)’ _Description_: ‘MOD(A,P)’ computes the remainder of the division of A by P. _Class_: Elemental function _Arguments_: A Shall be a scalar of type ‘INTEGER’, ‘REAL’ or ‘UNSIGNED’. P Shall be a scalar of the same type and kind as A and not equal to zero. (As a GNU extension, arguments of different kinds are permitted.) _Return value_: The return value is the result of ‘A - (INT(A/P) * P)’. The type and kind of the return value is the same as that of the arguments. The returned value has the same sign as A and a magnitude less than the magnitude of P. (As a GNU extension, kind is the largest kind of the actual arguments.) _Notes_: ‘MOD’ and ‘MODULO’ yield identical results if their arguments are ‘UNSIGNED’. _Example_: program test_mod print *, mod(17,3) print *, mod(17.5,5.5) print *, mod(17.5d0,5.5) print *, mod(17.5,5.5d0) print *, mod(-17,3) print *, mod(-17.5,5.5) print *, mod(-17.5d0,5.5) print *, mod(-17.5,5.5d0) print *, mod(17,-3) print *, mod(17.5,-5.5) print *, mod(17.5d0,-5.5) print *, mod(17.5,-5.5d0) end program test_mod _Specific names_: Name Arguments Return type Standard ------------------------------------------------------------------------ ‘MOD(A,P)’ ‘INTEGER A,P’ ‘INTEGER’ Fortran 77 and later ‘AMOD(A,P)’ ‘REAL(4) A,P’ ‘REAL(4)’ Fortran 77 and later ‘DMOD(A,P)’ ‘REAL(8) A,P’ ‘REAL(8)’ Fortran 77 and later ‘BMOD(A,P)’ ‘INTEGER(1) A,P’ ‘INTEGER(1)’ GNU extension ‘IMOD(A,P)’ ‘INTEGER(2) A,P’ ‘INTEGER(2)’ GNU extension ‘JMOD(A,P)’ ‘INTEGER(4) A,P’ ‘INTEGER(4)’ GNU extension ‘KMOD(A,P)’ ‘INTEGER(8) A,P’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 77 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’. _See also_: *note MODULO::  File: gfortran.info, Node: MODULO, Next: MOVE_ALLOC, Prev: MOD, Up: Intrinsic Procedures 8.201 ‘MODULO’ -- Modulo function ================================= _Synopsis_: ‘RESULT = MODULO(A, P)’ _Description_: ‘MODULO(A,P)’ computes the A modulo P. _Class_: Elemental function _Arguments_: A Shall be a scalar of type ‘INTEGER’ or ‘REAL’. P Shall be a scalar of the same type and kind as A. It shall not be zero. (As a GNU extension, arguments of different kinds are permitted.) _Return value_: The type and kind of the result are those of the arguments. (As a GNU extension, kind is the largest kind of the actual arguments.) If A and P are of type ‘INTEGER’ or ‘UNSIGNED’: ‘MODULO(A,P)’ has the value R such that ‘A=Q*P+R’, where Q is an integer and R is between 0 (inclusive) and P (exclusive). If A and P are of type ‘REAL’: ‘MODULO(A,P)’ has the value of ‘A - FLOOR (A / P) * P’. The returned value has the same sign as P and a magnitude less than the magnitude of P. _Notes_: ‘MOD’ and ‘MODULO’ yield identical results if their arguments are ‘UNSIGNED’. _Example_: program test_modulo print *, modulo(17,3) print *, modulo(17.5,5.5) print *, modulo(-17,3) print *, modulo(-17.5,5.5) print *, modulo(17,-3) print *, modulo(17.5,-5.5) end program _Standard_: Fortran 95 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note MOD::  File: gfortran.info, Node: MOVE_ALLOC, Next: MVBITS, Prev: MODULO, Up: Intrinsic Procedures 8.202 ‘MOVE_ALLOC’ -- Move allocation from one object to another ================================================================ _Synopsis_: ‘CALL MOVE_ALLOC(FROM, TO)’ _Description_: ‘MOVE_ALLOC(FROM, TO)’ moves the allocation from FROM to TO. FROM becomes deallocated in the process. _Class_: Pure subroutine _Arguments_: FROM ‘ALLOCATABLE’, ‘INTENT(INOUT)’, may be of any type and kind. TO ‘ALLOCATABLE’, ‘INTENT(OUT)’, shall be of the same type, kind and rank as FROM. _Return value_: None _Example_: program test_move_alloc integer, allocatable :: a(:), b(:) allocate(a(3)) a = [ 1, 2, 3 ] call move_alloc(a, b) print *, allocated(a), allocated(b) print *, b end program test_move_alloc _Standard_: Fortran 2003 and later  File: gfortran.info, Node: MVBITS, Next: NEAREST, Prev: MOVE_ALLOC, Up: Intrinsic Procedures 8.203 ‘MVBITS’ -- Move bits from one integer to another ======================================================= _Synopsis_: ‘CALL MVBITS(FROM, FROMPOS, LEN, TO, TOPOS)’ _Description_: Moves LEN bits from positions FROMPOS through ‘FROMPOS+LEN-1’ of FROM to positions TOPOS through ‘TOPOS+LEN-1’ of TO. The portion of argument TO not affected by the movement of bits is unchanged. The values of ‘FROMPOS+LEN-1’ and ‘TOPOS+LEN-1’ must be less than ‘BIT_SIZE(FROM)’. _Class_: Elemental subroutine _Arguments_: FROM The type shall be ‘INTEGER’ or ‘UNSIGNED’. FROMPOS The type shall be ‘INTEGER’. LEN The type shall be ‘INTEGER’. TO The type shall be of the same type and kind as FROM. TOPOS The type shall be ‘INTEGER’. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘MVBITS(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 90 and later ‘BMVBITS(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘IMVBITS(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JMVBITS(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KMVBITS(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::). _See also_: *note IBCLR::, *note IBSET::, *note IBITS::, *note IAND::, *note IOR::, *note IEOR::  File: gfortran.info, Node: NEAREST, Next: NEW_LINE, Prev: MVBITS, Up: Intrinsic Procedures 8.204 ‘NEAREST’ -- Nearest representable number =============================================== _Synopsis_: ‘RESULT = NEAREST(X, S)’ _Description_: ‘NEAREST(X, S)’ returns the processor-representable number nearest to ‘X’ in the direction indicated by the sign of ‘S’. _Class_: Elemental function _Arguments_: X Shall be of type ‘REAL’. S Shall be of type ‘REAL’ and not equal to zero. _Return value_: The return value is of the same type as ‘X’. If ‘S’ is positive, ‘NEAREST’ returns the processor-representable number greater than ‘X’ and nearest to it. If ‘S’ is negative, ‘NEAREST’ returns the processor-representable number smaller than ‘X’ and nearest to it. _Example_: program test_nearest real :: x, y x = nearest(42.0, 1.0) y = nearest(42.0, -1.0) write (*,"(3(G20.15))") x, y, x - y end program test_nearest _Standard_: Fortran 90 and later  File: gfortran.info, Node: NEW_LINE, Next: NINT, Prev: NEAREST, Up: Intrinsic Procedures 8.205 ‘NEW_LINE’ -- New line character ====================================== _Synopsis_: ‘RESULT = NEW_LINE(C)’ _Description_: ‘NEW_LINE(C)’ returns the new-line character. _Class_: Inquiry function _Arguments_: C The argument shall be a scalar or array of the type ‘CHARACTER’. _Return value_: Returns a CHARACTER scalar of length one with the new-line character of the same kind as parameter C. _Example_: program newline implicit none write(*,'(A)') 'This is record 1.'//NEW_LINE('A')//'This is record 2.' end program newline _Standard_: Fortran 2003 and later  File: gfortran.info, Node: NINT, Next: NORM2, Prev: NEW_LINE, Up: Intrinsic Procedures 8.206 ‘NINT’ -- Nearest whole number ==================================== _Synopsis_: ‘RESULT = NINT(A [, KIND])’ _Description_: ‘NINT(A)’ rounds its argument to the nearest whole number. _Class_: Elemental function _Arguments_: A The type of the argument shall be ‘REAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: Returns A with the fractional portion of its magnitude eliminated by rounding to the nearest whole number and with its sign preserved, converted to an ‘INTEGER’ of the default kind. _Example_: program test_nint real(4) x4 real(8) x8 x4 = 1.234E0_4 x8 = 4.321_8 print *, nint(x4), idnint(x8) end program test_nint _Specific names_: Name Argument Return Type Standard ------------------------------------------------------------------------- ‘NINT(A)’ ‘REAL(4) A’ ‘INTEGER’ Fortran 77 and later ‘IDNINT(A)’ ‘REAL(8) A’ ‘INTEGER’ Fortran 77 and later _Standard_: Fortran 77 and later, with KIND argument Fortran 90 and later _See also_: *note CEILING::, *note FLOOR::  File: gfortran.info, Node: NORM2, Next: NOT, Prev: NINT, Up: Intrinsic Procedures 8.207 ‘NORM2’ -- Euclidean vector norms ======================================= _Synopsis_: ‘RESULT = NORM2(ARRAY[, DIM])’ _Description_: Calculates the Euclidean vector norm (L_2 norm) of ARRAY along dimension DIM. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘REAL’ DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of ARRAY. _Return value_: The result is of the same type as ARRAY. If DIM is absent, a scalar with the square root of the sum of all elements in ARRAY squared is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned. _Example_: PROGRAM test_sum REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ] print *, NORM2(x) ! = sqrt(55.) ~ 7.416 END PROGRAM _Standard_: Fortran 2008 and later  File: gfortran.info, Node: NOT, Next: NULL, Prev: NORM2, Up: Intrinsic Procedures 8.208 ‘NOT’ -- Logical negation =============================== _Synopsis_: ‘RESULT = NOT(I)’ _Description_: ‘NOT’ returns the bitwise Boolean inverse of I. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. _Return value_: The return type is ‘INTEGER’, of the same kind as the argument. _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘NOT(A)’ ‘INTEGER A’ ‘INTEGER’ Fortran 95 and later ‘BNOT(A)’ ‘INTEGER(1) A’ ‘INTEGER(1)’ GNU extension ‘INOT(A)’ ‘INTEGER(2) A’ ‘INTEGER(2)’ GNU extension ‘JNOT(A)’ ‘INTEGER(4) A’ ‘INTEGER(4)’ GNU extension ‘KNOT(A)’ ‘INTEGER(8) A’ ‘INTEGER(8)’ GNU extension _Standard_: Fortran 90 and later, has overloads that are GNU extensions, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note IAND::, *note IEOR::, *note IOR::, *note IBITS::, *note IBSET::, *note IBCLR::  File: gfortran.info, Node: NULL, Next: NUM_IMAGES, Prev: NOT, Up: Intrinsic Procedures 8.209 ‘NULL’ -- Function that returns an disassociated pointer ============================================================== _Synopsis_: ‘PTR => NULL([MOLD])’ _Description_: Returns a disassociated pointer. If MOLD is present, a disassociated pointer of the same type is returned, otherwise the type is determined by context. In Fortran 95, MOLD is optional. Please note that Fortran 2003 includes cases where it is required. _Class_: Transformational function _Arguments_: MOLD (Optional) shall be a pointer of any association status and of any type. _Return value_: A disassociated pointer. _Example_: REAL, POINTER, DIMENSION(:) :: VEC => NULL () _Standard_: Fortran 95 and later _See also_: *note ASSOCIATED::  File: gfortran.info, Node: NUM_IMAGES, Next: OR, Prev: NULL, Up: Intrinsic Procedures 8.210 ‘NUM_IMAGES’ -- Function that returns the number of images ================================================================ _Synopsis_: ‘RESULT = NUM_IMAGES(DISTANCE, FAILED)’ _Description_: Returns the number of images. _Class_: Transformational function _Arguments_: DISTANCE (optional, intent(in)) Nonnegative scalar integer FAILED (optional, intent(in)) Scalar logical expression _Return value_: Scalar default-kind integer. If DISTANCE is not present or has value 0, the number of images in the current team is returned. For values smaller or equal distance to the initial team, it returns the number of images index on the ancestor team that has a distance of DISTANCE from the invoking team. If DISTANCE is larger than the distance to the initial team, the number of images of the initial team is returned. If FAILED is not present the total number of images is returned; if it has the value ‘.TRUE.’, the number of failed images is returned, otherwise, the number of images that do have not the failed status. _Example_: INTEGER :: value[*] INTEGER :: i value = THIS_IMAGE() SYNC ALL IF (THIS_IMAGE() == 1) THEN DO i = 1, NUM_IMAGES() WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i] END DO END IF _Standard_: Fortran 2008 and later. With DISTANCE or FAILED argument, Technical Specification (TS) 18508 or later _See also_: *note THIS_IMAGE::, *note IMAGE_INDEX::  File: gfortran.info, Node: OR, Next: OUT_OF_RANGE, Prev: NUM_IMAGES, Up: Intrinsic Procedures 8.211 ‘OR’ -- Bitwise logical OR ================================ _Synopsis_: ‘RESULT = OR(I, J)’ _Description_: Bitwise logical ‘OR’. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. For integer arguments, programmers should consider the use of the *note IOR:: intrinsic defined by the Fortran standard. _Class_: Function _Arguments_: I The type shall be either a scalar ‘INTEGER’ type or a scalar ‘LOGICAL’ type or a boz-literal-constant. J The type shall be the same as the type of I or a boz-literal-constant. I and J shall not both be boz-literal-constants. If either I and J is a boz-literal-constant, then the other argument must be a scalar ‘INTEGER’. _Return value_: The return type is either a scalar ‘INTEGER’ or a scalar ‘LOGICAL’. If the kind type parameters differ, then the smaller kind type is implicitly converted to larger kind, and the return has the larger kind. A boz-literal-constant is converted to an ‘INTEGER’ with the kind type parameter of the other argument as-if a call to *note INT:: occurred. _Example_: PROGRAM test_or LOGICAL :: T = .TRUE., F = .FALSE. INTEGER :: a, b DATA a / Z'F' /, b / Z'3' / WRITE (*,*) OR(T, T), OR(T, F), OR(F, T), OR(F, F) WRITE (*,*) OR(a, b) END PROGRAM _Standard_: GNU extension _See also_: Fortran 95 elemental function: *note IOR::  File: gfortran.info, Node: OUT_OF_RANGE, Next: PACK, Prev: OR, Up: Intrinsic Procedures 8.212 ‘OUT_OF_RANGE’ -- Range check for numerical conversion ============================================================ _Synopsis_: ‘RESULT = OUT_OF_RANGE(X, MOLD[, ROUND])’ _Description_: ‘OUT_OF_RANGE(X, MOLD[, ROUND])’ determines if the value of ‘X’ can be safely converted to an object with the type of argument ‘MOLD’. _Class_: Elemental function _Arguments_: X The type shall be either ‘INTEGER’, ‘UNSIGNED’ or ‘REAL’. MOLD The type shall be a scalar ‘INTEGER’, ‘UNSIGNED’ or ‘REAL’. If it is a variable, it need not be defined. ROUND (Optional) A scalar ‘LOGICAL’ that shall only be present if X is of type ‘REAL’ and MOLD is of type ‘INTEGER’ or ‘UNSIGNED’. _Return value_: The return value is of type ‘LOGICAL’. If MOLD is of type ‘INTEGER’ or ‘UNSIGNED’, and ROUND is absent or present with the value false, the result is true if and only if the value of X is an IEEE infinity or NaN, or if the integer with largest magnitude that lies between zero and X inclusive is not representable by objects with the type and kind of MOLD. If MOLD is of type ‘INTEGER’ or ‘UNSIGNED’, and ROUND is present with the value true, the result is true if and only if the value of X is an IEEE infinity or NaN, or if the integer nearest X, or the integer of greater magnitude if two integers are equally near to X, is not representable by objects with the type and kind of MOLD. Otherwise, the result is true if and only if the value of X is an IEEE infinity or NaN that is not supported by objects of the type and kind of MOLD, or if X is a finite number and the result of rounding the value of X to the model for the kind of MOLD has magnitude larger than that of the largest finite number with the same sign as X that is representable by objects with the type and kind of MOLD. _Example_: PROGRAM test_out_of_range PRINT *, OUT_OF_RANGE (-128.5, 0_1) ! Will print: F PRINT *, OUT_OF_RANGE (-128.5, 0_1, .TRUE.) ! Will print: T END PROGRAM _Standard_: Fortran 2018  File: gfortran.info, Node: PACK, Next: PARITY, Prev: OUT_OF_RANGE, Up: Intrinsic Procedures 8.213 ‘PACK’ -- Pack an array into an array of rank one ======================================================= _Synopsis_: ‘RESULT = PACK(ARRAY, MASK[,VECTOR])’ _Description_: Stores the elements of ARRAY in an array of rank one. The beginning of the resulting array is made up of elements whose MASK equals ‘TRUE’. Afterwards, positions are filled with elements taken from VECTOR. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of any type. MASK Shall be an array of type ‘LOGICAL’ and of the same size as ARRAY. Alternatively, it may be a ‘LOGICAL’ scalar. VECTOR (Optional) shall be an array of the same type as ARRAY and of rank one. If present, the number of elements in VECTOR shall be equal to or greater than the number of true elements in MASK. If MASK is scalar, the number of elements in VECTOR shall be equal to or greater than the number of elements in ARRAY. _Return value_: The result is an array of rank one and the same type as that of ARRAY. If VECTOR is present, the result size is that of VECTOR, the number of ‘TRUE’ values in MASK otherwise. _Example_: Gathering nonzero elements from an array: PROGRAM test_pack_1 INTEGER :: m(6) m = (/ 1, 0, 0, 0, 5, 0 /) WRITE(*, FMT="(6(I0, ' '))") pack(m, m /= 0) ! "1 5" END PROGRAM Gathering nonzero elements from an array and appending elements from VECTOR: PROGRAM test_pack_2 INTEGER :: m(4) m = (/ 1, 0, 0, 2 /) ! The following results in "1 2 3 4" WRITE(*, FMT="(4(I0, ' '))") pack(m, m /= 0, (/ 0, 0, 3, 4 /)) END PROGRAM _Standard_: Fortran 90 and later _See also_: *note UNPACK::  File: gfortran.info, Node: PARITY, Next: PERROR, Prev: PACK, Up: Intrinsic Procedures 8.214 ‘PARITY’ -- Reduction with exclusive OR ============================================= _Synopsis_: ‘RESULT = PARITY(MASK[, DIM])’ _Description_: Calculates the parity, i.e. the reduction using ‘.XOR.’, of MASK along dimension DIM. _Class_: Transformational function _Arguments_: MASK Shall be an array of type ‘LOGICAL’ DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of MASK. _Return value_: The result is of the same type as MASK. If DIM is absent, a scalar with the parity of all elements in MASK is returned, i.e. true if an odd number of elements is ‘.true.’ and false otherwise. If DIM is present, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of MASK with dimension DIM dropped is returned. _Example_: PROGRAM test_sum LOGICAL :: x(2) = [ .true., .false. ] print *, PARITY(x) ! prints "T" (true). END PROGRAM _Standard_: Fortran 2008 and later  File: gfortran.info, Node: PERROR, Next: POPCNT, Prev: PARITY, Up: Intrinsic Procedures 8.215 ‘PERROR’ -- Print system error message ============================================ _Synopsis_: ‘CALL PERROR(STRING)’ _Description_: Prints (on the C ‘stderr’ stream) a newline-terminated error message corresponding to the last system error. This is prefixed by STRING, a colon and a space. See ‘perror(3)’. _Class_: Subroutine _Arguments_: STRING A scalar of type ‘CHARACTER’ and of the default kind. _Standard_: GNU extension _See also_: *note IERRNO::  File: gfortran.info, Node: POPCNT, Next: POPPAR, Prev: PERROR, Up: Intrinsic Procedures 8.216 ‘POPCNT’ -- Number of bits set ==================================== _Synopsis_: ‘RESULT = POPCNT(I)’ _Description_: ‘POPCNT(I)’ returns the number of bits set ('1' bits) in the binary representation of ‘I’. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Example_: program test_population print *, popcnt(127), poppar(127) print *, popcnt(huge(0_4)), poppar(huge(0_4)) print *, popcnt(huge(0_8)), poppar(huge(0_8)) end program test_population _Standard_: Fortran 2008 and later _See also_: *note POPPAR::, *note LEADZ::, *note TRAILZ::  File: gfortran.info, Node: POPPAR, Next: PRECISION, Prev: POPCNT, Up: Intrinsic Procedures 8.217 ‘POPPAR’ -- Parity of the number of bits set ================================================== _Synopsis_: ‘RESULT = POPPAR(I)’ _Description_: ‘POPPAR(I)’ returns parity of the integer ‘I’, i.e. the parity of the number of bits set ('1' bits) in the binary representation of ‘I’. It is equal to 0 if ‘I’ has an even number of bits set, and 1 for an odd number of '1' bits. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Example_: program test_population print *, popcnt(127), poppar(127) print *, popcnt(huge(0_4)), poppar(huge(0_4)) print *, popcnt(huge(0_8)), poppar(huge(0_8)) end program test_population _Standard_: Fortran 2008 and later _See also_: *note POPCNT::, *note LEADZ::, *note TRAILZ::  File: gfortran.info, Node: PRECISION, Next: PRESENT, Prev: POPPAR, Up: Intrinsic Procedures 8.218 ‘PRECISION’ -- Decimal precision of a real kind ===================================================== _Synopsis_: ‘RESULT = PRECISION(X)’ _Description_: ‘PRECISION(X)’ returns the decimal precision in the model of the type of ‘X’. _Class_: Inquiry function _Arguments_: X Shall be of type ‘REAL’ or ‘COMPLEX’. It may be scalar or valued. _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Example_: program prec_and_range real(kind=4) :: x(2) complex(kind=8) :: y print *, precision(x), range(x) print *, precision(y), range(y) end program prec_and_range _Standard_: Fortran 90 and later _See also_: *note SELECTED_REAL_KIND::, *note RANGE::  File: gfortran.info, Node: PRESENT, Next: PRODUCT, Prev: PRECISION, Up: Intrinsic Procedures 8.219 ‘PRESENT’ -- Determine whether an optional dummy argument is specified ============================================================================ _Synopsis_: ‘RESULT = PRESENT(A)’ _Description_: Determines whether an optional dummy argument is present. _Class_: Inquiry function _Arguments_: A May be of any type and may be a pointer, scalar or array value, or a dummy procedure. It shall be the name of an optional dummy argument accessible within the current subroutine or function. _Return value_: Returns either ‘TRUE’ if the optional argument A is present, or ‘FALSE’ otherwise. _Example_: PROGRAM test_present WRITE(*,*) f(), f(42) ! "F T" CONTAINS LOGICAL FUNCTION f(x) INTEGER, INTENT(IN), OPTIONAL :: x f = PRESENT(x) END FUNCTION END PROGRAM _Standard_: Fortran 90 and later  File: gfortran.info, Node: PRODUCT, Next: RADIX, Prev: PRESENT, Up: Intrinsic Procedures 8.220 ‘PRODUCT’ -- Product of array elements ============================================ _Synopsis_: ‘RESULT = PRODUCT(ARRAY[, MASK])’ ‘RESULT = PRODUCT(ARRAY, DIM[, MASK])’ _Description_: Multiplies the elements of ARRAY along dimension DIM if the corresponding element in MASK is ‘TRUE’. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’. DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of ARRAY. MASK (Optional) shall be of type ‘LOGICAL’ and either be a scalar or an array of the same shape as ARRAY. _Return value_: The result is of the same type as ARRAY. If DIM is absent, a scalar with the product of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned. _Example_: PROGRAM test_product INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /) print *, PRODUCT(x) ! all elements, product = 120 print *, PRODUCT(x, MASK=MOD(x, 2)==1) ! odd elements, product = 15 END PROGRAM _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note SUM::  File: gfortran.info, Node: RADIX, Next: RAN, Prev: PRODUCT, Up: Intrinsic Procedures 8.221 ‘RADIX’ -- Base of a model number ======================================= _Synopsis_: ‘RESULT = RADIX(X)’ _Description_: ‘RADIX(X)’ returns the base of the model representing the entity X. _Class_: Inquiry function _Arguments_: X Shall be of type ‘INTEGER’ or ‘REAL’ _Return value_: The return value is a scalar of type ‘INTEGER’ and of the default integer kind. _Example_: program test_radix print *, "The radix for the default integer kind is", radix(0) print *, "The radix for the default real kind is", radix(0.0) end program test_radix _Standard_: Fortran 90 and later _See also_: *note SELECTED_REAL_KIND::  File: gfortran.info, Node: RAN, Next: RAND, Prev: RADIX, Up: Intrinsic Procedures 8.222 ‘RAN’ -- Real pseudo-random number ======================================== _Description_: For compatibility with HP FORTRAN 77/iX, the ‘RAN’ intrinsic is provided as an alias for ‘RAND’. See *note RAND:: for complete documentation. _Class_: Function _Standard_: GNU extension _See also_: *note RAND::, *note RANDOM_NUMBER::  File: gfortran.info, Node: RAND, Next: RANDOM_INIT, Prev: RAN, Up: Intrinsic Procedures 8.223 ‘RAND’ -- Real pseudo-random number ========================================= _Synopsis_: ‘RESULT = RAND(I)’ _Description_: ‘RAND(FLAG)’ returns a pseudo-random number from a uniform distribution between 0 and 1. If FLAG is 0, the next number in the current sequence is returned; if FLAG is 1, the generator is restarted by ‘CALL SRAND(0)’; if FLAG has any other value, it is used as a new seed with ‘SRAND’. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. It implements a simple modulo generator as provided by ‘g77’. For new code, one should consider the use of *note RANDOM_NUMBER:: as it implements a superior algorithm. _Class_: Function _Arguments_: I Shall be a scalar ‘INTEGER’ of kind 4. _Return value_: The return value is of ‘REAL’ type and the default kind. _Example_: program test_rand integer,parameter :: seed = 86456 call srand(seed) print *, rand(), rand(), rand(), rand() print *, rand(seed), rand(), rand(), rand() end program test_rand _Standard_: GNU extension _See also_: *note SRAND::, *note RANDOM_NUMBER::  File: gfortran.info, Node: RANDOM_INIT, Next: RANDOM_NUMBER, Prev: RAND, Up: Intrinsic Procedures 8.224 ‘RANDOM_INIT’ -- Initialize a pseudo-random number generator ================================================================== _Synopsis_: ‘CALL RANDOM_INIT(REPEATABLE, IMAGE_DISTINCT)’ _Description_: Initializes the state of the pseudorandom number generator used by ‘RANDOM_NUMBER’. _Class_: Subroutine _Arguments_: REPEATABLE Shall be a scalar with a ‘LOGICAL’ type, and it is ‘INTENT(IN)’. If it is ‘.true.’, the seed is set to a processor-dependent value that is the same each time ‘RANDOM_INIT’ is called from the same image. The term "same image" means a single instance of program execution. The sequence of random numbers is the same for repeated execution of the program with the same execution environment. If it is ‘.false.’, the seed is set to a processor-dependent value. IMAGE_DISTINCT Shall be a scalar with a ‘LOGICAL’ type, and it is ‘INTENT(IN)’. If it is ‘.true.’, the seed is set to a processor-dependent value that is distinct from the seed set by a call to ‘RANDOM_INIT’ in another image. If it is ‘.false.’, the seed is set to a value that is the same on every image calling ‘RANDOM_INIT’. _Example_: program test_random_seed implicit none real x(3), y(3) call random_init(.true., .true.) call random_number(x) call random_init(.true., .true.) call random_number(y) ! x and y are the same sequence if (any(x /= y)) call abort end program test_random_seed _Standard_: Fortran 2018 _See also_: *note RANDOM_NUMBER::, *note RANDOM_SEED::  File: gfortran.info, Node: RANDOM_NUMBER, Next: RANDOM_SEED, Prev: RANDOM_INIT, Up: Intrinsic Procedures 8.225 ‘RANDOM_NUMBER’ -- Pseudo-random number ============================================= _Synopsis_: ‘CALL RANDOM_NUMBER(HARVEST)’ _Description_: For ‘REAL’ argument, returns a single pseudorandom number or an array of pseudorandom numbers from the uniform distribution over the range 0 <= x < 1. For ‘UNSIGNED’ argument returns a single pseudorandom number or an array of pseudorandom numbers in over the range of 0 <= x <= HUGE(HARVEST). The runtime-library implements the xoshiro256** pseudorandom number generator (PRNG). This generator has a period of 2^{256} - 1, and when using multiple threads up to 2^{128} threads can each generate 2^{128} random numbers before any aliasing occurs. Note that in a multi-threaded program (e.g. using OpenMP directives), each thread has its own random number state. For details of the seeding procedure, see the documentation for the ‘RANDOM_SEED’ intrinsic. _Class_: Subroutine _Arguments_: HARVEST Shall be a scalar or an array of type ‘REAL’. _Example_: program test_random_number REAL :: r(5,5) CALL RANDOM_NUMBER(r) end program _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note RANDOM_SEED::, *note RANDOM_INIT::  File: gfortran.info, Node: RANDOM_SEED, Next: RANGE, Prev: RANDOM_NUMBER, Up: Intrinsic Procedures 8.226 ‘RANDOM_SEED’ -- Initialize a pseudo-random number sequence ================================================================= _Synopsis_: ‘CALL RANDOM_SEED([SIZE, PUT, GET])’ _Description_: Restarts or queries the state of the pseudorandom number generator used by ‘RANDOM_NUMBER’. If ‘RANDOM_SEED’ is called without arguments, it is seeded with random data retrieved from the operating system. As an extension to the Fortran standard, the GFortran ‘RANDOM_NUMBER’ supports multiple threads. Each thread in a multi-threaded program has its own seed. When ‘RANDOM_SEED’ is called either without arguments or with the PUT argument, the given seed is copied into a master seed as well as the seed of the current thread. When a new thread uses ‘RANDOM_NUMBER’ for the first time, the seed is copied from the master seed, and forwarded N * 2^{128} steps to guarantee that the random stream does not alias any other stream in the system, where N is the number of threads that have used ‘RANDOM_NUMBER’ so far during the program execution. _Class_: Subroutine _Arguments_: SIZE (Optional) Shall be a scalar and of type default ‘INTEGER’, with ‘INTENT(OUT)’. It specifies the minimum size of the arrays used with the PUT and GET arguments. PUT (Optional) Shall be an array of type default ‘INTEGER’ and rank one. It is ‘INTENT(IN)’ and the size of the array must be larger than or equal to the number returned by the SIZE argument. GET (Optional) Shall be an array of type default ‘INTEGER’ and rank one. It is ‘INTENT(OUT)’ and the size of the array must be larger than or equal to the number returned by the SIZE argument. _Example_: program test_random_seed implicit none integer, allocatable :: seed(:) integer :: n call random_seed(size = n) allocate(seed(n)) call random_seed(get=seed) write (*, *) seed end program test_random_seed _Standard_: Fortran 90 and later _See also_: *note RANDOM_NUMBER::, *note RANDOM_INIT::  File: gfortran.info, Node: RANGE, Next: RANK, Prev: RANDOM_SEED, Up: Intrinsic Procedures 8.227 ‘RANGE’ -- Decimal exponent range ======================================= _Synopsis_: ‘RESULT = RANGE(X)’ _Description_: ‘RANGE(X)’ returns the decimal exponent range in the model of the type of ‘X’. _Class_: Inquiry function _Arguments_: X Shall be of type ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’. _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. _Example_: See ‘PRECISION’ for an example. _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note SELECTED_REAL_KIND::, *note PRECISION::  File: gfortran.info, Node: RANK, Next: REAL, Prev: RANGE, Up: Intrinsic Procedures 8.228 ‘RANK’ -- Rank of a data object ===================================== _Synopsis_: ‘RESULT = RANK(A)’ _Description_: ‘RANK(A)’ returns the rank of a scalar or array data object. _Class_: Inquiry function _Arguments_: A can be of any type _Return value_: The return value is of type ‘INTEGER’ and of the default integer kind. For arrays, their rank is returned; for scalars zero is returned. _Example_: program test_rank integer :: a real, allocatable :: b(:,:) print *, rank(a), rank(b) ! Prints: 0 2 end program test_rank _Standard_: Technical Specification (TS) 29113  File: gfortran.info, Node: REAL, Next: RENAME, Prev: RANK, Up: Intrinsic Procedures 8.229 ‘REAL’ -- Convert to real type ==================================== _Synopsis_: ‘RESULT = REAL(A [, KIND])’ ‘RESULT = REALPART(Z)’ _Description_: ‘REAL(A [, KIND])’ converts its argument A to a real type. The ‘REALPART’ function is provided for compatibility with ‘g77’, and its use is strongly discouraged. _Class_: Elemental function _Arguments_: A Shall be ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: These functions return a ‘REAL’ variable or array under the following rules: (A) ‘REAL(A)’ is converted to a default real type if A is an integer, real or unsigned variable. (B) ‘REAL(A)’ is converted to a real type with the kind type parameter of A if A is a complex variable. (C) ‘REAL(A, KIND)’ is converted to a real type with kind type parameter KIND if A is a complex, integer, real or unsigned variable. _Example_: program test_real complex :: x = (1.0, 2.0) print *, real(x), real(x,8), realpart(x) end program test_real _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘FLOAT(A)’ ‘INTEGER(4)’ ‘REAL(4)’ Fortran 77 and later ‘DFLOAT(A)’ ‘INTEGER(4)’ ‘REAL(8)’ GNU extension ‘FLOATI(A)’ ‘INTEGER(2)’ ‘REAL(4)’ GNU extension (-fdec) ‘FLOATJ(A)’ ‘INTEGER(4)’ ‘REAL(4)’ GNU extension (-fdec) ‘FLOATK(A)’ ‘INTEGER(8)’ ‘REAL(4)’ GNU extension (-fdec) ‘SNGL(A)’ ‘REAL(8)’ ‘REAL(4)’ Fortran 77 and later _Standard_: Fortran 77 and later, with KIND argument Fortran 90 and later, has GNU extensions. Extension for ‘UNSIGNED’ (*note Unsigned integers::). _See also_: *note DBLE::  File: gfortran.info, Node: RENAME, Next: REPEAT, Prev: REAL, Up: Intrinsic Procedures 8.230 ‘RENAME’ -- Rename a file =============================== _Synopsis_: ‘CALL RENAME(PATH1, PATH2 [, STATUS])’ ‘STATUS = RENAME(PATH1, PATH2)’ _Description_: Renames a file from file PATH1 to PATH2. A null character (‘CHAR(0)’) can be used to mark the end of the names in PATH1 and PATH2; otherwise, trailing blanks in the file names are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see ‘rename(2)’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: PATH1 Shall be of default ‘CHARACTER’ type. PATH2 Shall be of default ‘CHARACTER’ type. STATUS (Optional) Shall be of default ‘INTEGER’ type. _Standard_: GNU extension _See also_: *note LINK::  File: gfortran.info, Node: REPEAT, Next: RESHAPE, Prev: RENAME, Up: Intrinsic Procedures 8.231 ‘REPEAT’ -- Repeated string concatenation =============================================== _Synopsis_: ‘RESULT = REPEAT(STRING, NCOPIES)’ _Description_: Concatenates NCOPIES copies of a string. _Class_: Transformational function _Arguments_: STRING Shall be scalar and of type ‘CHARACTER’. NCOPIES Shall be scalar and of type ‘INTEGER’. _Return value_: A new scalar of type ‘CHARACTER’ built up from NCOPIES copies of STRING. _Example_: program test_repeat write(*,*) repeat("x", 5) ! "xxxxx" end program _Standard_: Fortran 90 and later  File: gfortran.info, Node: RESHAPE, Next: RRSPACING, Prev: REPEAT, Up: Intrinsic Procedures 8.232 ‘RESHAPE’ -- Function to reshape an array =============================================== _Synopsis_: ‘RESULT = RESHAPE(SOURCE, SHAPE[, PAD, ORDER])’ _Description_: Reshapes SOURCE to correspond to SHAPE. If necessary, the new array may be padded with elements from PAD or permuted as defined by ORDER. _Class_: Transformational function _Arguments_: SOURCE Shall be an array of any type. SHAPE Shall be of type ‘INTEGER’ and an array of rank one. Its values must be positive or zero. PAD (Optional) shall be an array of the same type as SOURCE. ORDER (Optional) shall be of type ‘INTEGER’ and an array of the same shape as SHAPE. Its values shall be a permutation of the numbers from 1 to n, where n is the size of SHAPE. If ORDER is absent, the natural ordering shall be assumed. _Return value_: The result is an array of shape SHAPE with the same type as SOURCE. _Example_: PROGRAM test_reshape INTEGER, DIMENSION(4) :: x WRITE(*,*) SHAPE(x) ! prints "4" WRITE(*,*) SHAPE(RESHAPE(x, (/2, 2/))) ! prints "2 2" END PROGRAM _Standard_: Fortran 90 and later _See also_: *note SHAPE::  File: gfortran.info, Node: RRSPACING, Next: RSHIFT, Prev: RESHAPE, Up: Intrinsic Procedures 8.233 ‘RRSPACING’ -- Reciprocal of the relative spacing ======================================================= _Synopsis_: ‘RESULT = RRSPACING(X)’ _Description_: ‘RRSPACING(X)’ returns the reciprocal of the relative spacing of model numbers near X. _Class_: Elemental function _Arguments_: X Shall be of type ‘REAL’. _Return value_: The return value is of the same type and kind as X. The value returned is equal to ‘ABS(FRACTION(X)) * FLOAT(RADIX(X))**DIGITS(X)’. _Standard_: Fortran 90 and later _See also_: *note SPACING::  File: gfortran.info, Node: RSHIFT, Next: SAME_TYPE_AS, Prev: RRSPACING, Up: Intrinsic Procedures 8.234 ‘RSHIFT’ -- Right shift bits ================================== _Synopsis_: ‘RESULT = RSHIFT(I, SHIFT)’ _Description_: ‘RSHIFT’ returns a value corresponding to I with all of the bits shifted right by SHIFT places. SHIFT shall be nonnegative and less than or equal to ‘BIT_SIZE(I)’, otherwise the result value is undefined. Bits shifted out from the right end are lost. The fill is arithmetic: the bits shifted in from the left end are equal to the leftmost bit, which in two's complement representation is the sign bit. This function has been superseded by the ‘SHIFTA’ intrinsic, which is standard in Fortran 2008 and later. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’. SHIFT The type shall be ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’ and of the same kind as I. _Standard_: GNU extension _See also_: *note ISHFT::, *note ISHFTC::, *note LSHIFT::, *note SHIFTA::, *note SHIFTR::, *note SHIFTL::  File: gfortran.info, Node: SAME_TYPE_AS, Next: SCALE, Prev: RSHIFT, Up: Intrinsic Procedures 8.235 ‘SAME_TYPE_AS’ -- Query dynamic types for equality ======================================================== _Synopsis_: ‘RESULT = SAME_TYPE_AS(A, B)’ _Description_: Query dynamic types for equality. _Class_: Inquiry function _Arguments_: A Shall be an object of extensible declared type or unlimited polymorphic. B Shall be an object of extensible declared type or unlimited polymorphic. _Return value_: The return value is a scalar of type default logical. It is true if and only if the dynamic type of A is the same as the dynamic type of B. _Standard_: Fortran 2003 and later _See also_: *note EXTENDS_TYPE_OF::  File: gfortran.info, Node: SCALE, Next: SCAN, Prev: SAME_TYPE_AS, Up: Intrinsic Procedures 8.236 ‘SCALE’ -- Scale a real value =================================== _Synopsis_: ‘RESULT = SCALE(X, I)’ _Description_: ‘SCALE(X,I)’ returns ‘X * RADIX(X)**I’. _Class_: Elemental function _Arguments_: X The type of the argument shall be a ‘REAL’. I The type of the argument shall be a ‘INTEGER’. _Return value_: The return value is of the same type and kind as X. Its value is ‘X * RADIX(X)**I’. _Example_: program test_scale real :: x = 178.1387e-4 integer :: i = 5 print *, scale(x,i), x*radix(x)**i end program test_scale _Standard_: Fortran 90 and later  File: gfortran.info, Node: SCAN, Next: SECNDS, Prev: SCALE, Up: Intrinsic Procedures 8.237 ‘SCAN’ -- Scan a string for the presence of a set of characters ===================================================================== _Synopsis_: ‘RESULT = SCAN(STRING, SET[, BACK [, KIND]])’ _Description_: Scans a STRING for any of the characters in a SET of characters. If BACK is either absent or equals ‘FALSE’, this function returns the position of the leftmost character of STRING that is in SET. If BACK equals ‘TRUE’, the rightmost position is returned. If no character of SET is found in STRING, the result is zero. _Class_: Elemental function _Arguments_: STRING Shall be of type ‘CHARACTER’. SET Shall be of type ‘CHARACTER’. BACK (Optional) shall be of type ‘LOGICAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Example_: PROGRAM test_scan WRITE(*,*) SCAN("FORTRAN", "AO") ! 2, found 'O' WRITE(*,*) SCAN("FORTRAN", "AO", .TRUE.) ! 6, found 'A' WRITE(*,*) SCAN("FORTRAN", "C++") ! 0, found none END PROGRAM _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note INDEX intrinsic::, *note VERIFY::  File: gfortran.info, Node: SECNDS, Next: SECOND, Prev: SCAN, Up: Intrinsic Procedures 8.238 ‘SECNDS’ -- Time function =============================== _Synopsis_: ‘RESULT = SECNDS (X)’ _Description_: ‘SECNDS(X)’ gets the time in seconds from the real-time system clock. X is a reference time, also in seconds. If this is zero, the time in seconds from midnight is returned. This function is non-standard and its use is discouraged. _Class_: Function _Arguments_: T Shall be of type ‘REAL(4)’. X Shall be of type ‘REAL(4)’. _Return value_: None _Example_: program test_secnds integer :: i real(4) :: t1, t2 print *, secnds (0.0) ! seconds since midnight t1 = secnds (0.0) ! reference time do i = 1, 10000000 ! do something end do t2 = secnds (t1) ! elapsed time print *, "Something took ", t2, " seconds." end program test_secnds _Standard_: GNU extension  File: gfortran.info, Node: SECOND, Next: SELECTED_CHAR_KIND, Prev: SECNDS, Up: Intrinsic Procedures 8.239 ‘SECOND’ -- CPU time function =================================== _Synopsis_: ‘CALL SECOND(TIME)’ ‘TIME = SECOND()’ _Description_: Returns a ‘REAL(4)’ value representing the elapsed CPU time in seconds. This provides the same functionality as the standard ‘CPU_TIME’ intrinsic, and is only included for backwards compatibility. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: TIME Shall be of type ‘REAL(4)’. _Return value_: In either syntax, TIME is set to the process's current runtime in seconds. _Standard_: GNU extension _See also_: *note CPU_TIME::  File: gfortran.info, Node: SELECTED_CHAR_KIND, Next: SELECTED_INT_KIND, Prev: SECOND, Up: Intrinsic Procedures 8.240 ‘SELECTED_CHAR_KIND’ -- Choose character kind =================================================== _Synopsis_: ‘RESULT = SELECTED_CHAR_KIND(NAME)’ _Description_: ‘SELECTED_CHAR_KIND(NAME)’ returns the kind value for the character set named NAME, if a character set with such a name is supported, or -1 otherwise. Currently, supported character sets include "ASCII" and "DEFAULT", which are equivalent, and "ISO_10646" (Universal Character Set, UCS-4) which is commonly known as Unicode. _Class_: Transformational function _Arguments_: NAME Shall be a scalar and of the default character type. _Example_: program character_kind use iso_fortran_env implicit none integer, parameter :: ascii = selected_char_kind ("ascii") integer, parameter :: ucs4 = selected_char_kind ('ISO_10646') character(kind=ascii, len=26) :: alphabet character(kind=ucs4, len=30) :: hello_world alphabet = ascii_"abcdefghijklmnopqrstuvwxyz" hello_world = ucs4_'Hello World and Ni Hao -- ' & // char (int (z'4F60'), ucs4) & // char (int (z'597D'), ucs4) write (*,*) alphabet open (output_unit, encoding='UTF-8') write (*,*) trim (hello_world) end program character_kind _Standard_: Fortran 2003 and later  File: gfortran.info, Node: SELECTED_INT_KIND, Next: SELECTED_LOGICAL_KIND, Prev: SELECTED_CHAR_KIND, Up: Intrinsic Procedures 8.241 ‘SELECTED_INT_KIND’ -- Choose integer kind ================================================ _Synopsis_: ‘RESULT = SELECTED_INT_KIND(R)’ _Description_: ‘SELECTED_INT_KIND(R)’ return the kind value of the smallest integer type that can represent all values ranging from -10^R (exclusive) to 10^R (exclusive). If there is no integer kind that accommodates this range, ‘SELECTED_INT_KIND’ returns -1. _Class_: Transformational function _Arguments_: R Shall be a scalar and of type ‘INTEGER’. _Example_: program large_integers integer,parameter :: k5 = selected_int_kind(5) integer,parameter :: k15 = selected_int_kind(15) integer(kind=k5) :: i5 integer(kind=k15) :: i15 print *, huge(i5), huge(i15) ! The following inequalities are always true print *, huge(i5) >= 10_k5**5-1 print *, huge(i15) >= 10_k15**15-1 end program large_integers _Standard_: Fortran 90 and later  File: gfortran.info, Node: SELECTED_LOGICAL_KIND, Next: SELECTED_REAL_KIND, Prev: SELECTED_INT_KIND, Up: Intrinsic Procedures 8.242 ‘SELECTED_LOGICAL_KIND’ -- Choose logical kind ==================================================== _Synopsis_: ‘RESULT = SELECTED_LOGICAL_KIND(BITS)’ _Description_: ‘SELECTED_LOGICAL_KIND(BITS)’ return the kind value of the smallest logical type whose storage size in bits is at least BITS. If there is no such logical kind, ‘SELECTED_LOGICAL_KIND’ returns -1. _Class_: Transformational function _Arguments_: BITS Shall be a scalar and of type ‘INTEGER’. _Example_: program logical_kinds integer, parameter :: k1 = selected_logical_kind(1) integer, parameter :: k40 = selected_logical_kind(40) logical(kind=k1) :: l1 ! At least one bit logical(kind=k40) :: l40 ! At least 40 bits ! What is their actual size? print *, storage_size(l1), storage_size(l40) end program logical_kinds _Standard_: Fortran 2023 and later  File: gfortran.info, Node: SELECTED_REAL_KIND, Next: SELECTED_UNSIGNED_KIND, Prev: SELECTED_LOGICAL_KIND, Up: Intrinsic Procedures 8.243 ‘SELECTED_REAL_KIND’ -- Choose real kind ============================================== _Synopsis_: ‘RESULT = SELECTED_REAL_KIND([P, R, RADIX])’ _Description_: ‘SELECTED_REAL_KIND(P,R)’ returns the kind value of a real data type with decimal precision of at least ‘P’ digits, exponent range of at least ‘R’, and with a radix of ‘RADIX’. _Class_: Transformational function _Arguments_: P (Optional) shall be a scalar and of type ‘INTEGER’. R (Optional) shall be a scalar and of type ‘INTEGER’. RADIX (Optional) shall be a scalar and of type ‘INTEGER’. Before Fortran 2008, at least one of the arguments R or P shall be present; since Fortran 2008, they are assumed to be zero if absent. _Return value_: ‘SELECTED_REAL_KIND’ returns the value of the kind type parameter of a real data type with decimal precision of at least ‘P’ digits, a decimal exponent range of at least ‘R’, and with the requested ‘RADIX’. If the ‘RADIX’ parameter is absent, real kinds with any radix can be returned. If more than one real data type meet the criteria, the kind of the data type with the smallest decimal precision is returned. If no real data type matches the criteria, the result is -1 if the processor does not support a real data type with a precision greater than or equal to ‘P’, but the ‘R’ and ‘RADIX’ requirements can be fulfilled -2 if the processor does not support a real type with an exponent range greater than or equal to ‘R’, but ‘P’ and ‘RADIX’ are fulfillable -3 if ‘RADIX’ but not ‘P’ and ‘R’ requirements are fulfillable -4 if ‘RADIX’ and either ‘P’ or ‘R’ requirements are fulfillable -5 if there is no real type with the given ‘RADIX’ _Example_: program real_kinds integer,parameter :: p6 = selected_real_kind(6) integer,parameter :: p10r100 = selected_real_kind(10,100) integer,parameter :: r400 = selected_real_kind(r=400) real(kind=p6) :: x real(kind=p10r100) :: y real(kind=r400) :: z print *, precision(x), range(x) print *, precision(y), range(y) print *, precision(z), range(z) end program real_kinds _Standard_: Fortran 90 and later, with ‘RADIX’ Fortran 2008 or later _See also_: *note PRECISION::, *note RANGE::, *note RADIX::  File: gfortran.info, Node: SELECTED_UNSIGNED_KIND, Next: SET_EXPONENT, Prev: SELECTED_REAL_KIND, Up: Intrinsic Procedures 8.244 ‘SELECTED_UNSIGNED_KIND’ -- Choose unsigned kind ====================================================== _Synopsis_: ‘RESULT = SELECTED_UNSIGNED_KIND(R)’ _Description_: ‘SELECTED_UNSIGNED_KIND(R)’ return the kind value of the smallest integer type that can represent all values ranging from 0 to 10^R (exclusive). If there is no unsigned kind that accommodates this range, ‘SELECTED_UNSIGNED_KIND’ returns -1. _Class_: Transformational function _Arguments_: R Shall be a scalar and of type ‘INTEGER’. _Example_: program large_unsigned integer,parameter :: k5 = selected_unsigned_kind(5) integer,parameter :: k15 = selected_unsigned_kind(15) unsigned(kind=k5) :: i5 unsigned(kind=k15) :: i15 print *, huge(i5), huge(i15) end program large_unsigned _Standard_: Extension for ‘UNSIGNED’ (*note Unsigned integers::)  File: gfortran.info, Node: SET_EXPONENT, Next: SHAPE, Prev: SELECTED_UNSIGNED_KIND, Up: Intrinsic Procedures 8.245 ‘SET_EXPONENT’ -- Set the exponent of the model ===================================================== _Synopsis_: ‘RESULT = SET_EXPONENT(X, I)’ _Description_: ‘SET_EXPONENT(X, I)’ returns the real number whose fractional part is that of X and whose exponent part is I. _Class_: Elemental function _Arguments_: X Shall be of type ‘REAL’. I Shall be of type ‘INTEGER’. _Return value_: The return value is of the same type and kind as X. The real number whose fractional part is that of X and whose exponent part if I is returned; it is ‘FRACTION(X) * RADIX(X)**I’. _Example_: PROGRAM test_setexp REAL :: x = 178.1387e-4 INTEGER :: i = 17 PRINT *, SET_EXPONENT(x, i), FRACTION(x) * RADIX(x)**i END PROGRAM _Standard_: Fortran 90 and later  File: gfortran.info, Node: SHAPE, Next: SHIFTA, Prev: SET_EXPONENT, Up: Intrinsic Procedures 8.246 ‘SHAPE’ -- Determine the shape of an array ================================================ _Synopsis_: ‘RESULT = SHAPE(SOURCE [, KIND])’ _Description_: Determines the shape of an array. _Class_: Inquiry function _Arguments_: SOURCE Shall be an array or scalar of any type. If SOURCE is a pointer it must be associated and allocatable arrays must be allocated. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: An ‘INTEGER’ array of rank one with as many elements as SOURCE has dimensions. The elements of the resulting array correspond to the extend of SOURCE along the respective dimensions. If SOURCE is a scalar, the result is the rank one array of size zero. If KIND is absent, the return value has the default integer kind otherwise the specified kind. _Example_: PROGRAM test_shape INTEGER, DIMENSION(-1:1, -1:2) :: A WRITE(*,*) SHAPE(A) ! (/ 3, 4 /) WRITE(*,*) SIZE(SHAPE(42)) ! (/ /) END PROGRAM _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note RESHAPE::, *note SIZE::  File: gfortran.info, Node: SHIFTA, Next: SHIFTL, Prev: SHAPE, Up: Intrinsic Procedures 8.247 ‘SHIFTA’ -- Right shift with fill ======================================= _Synopsis_: ‘RESULT = SHIFTA(I, SHIFT)’ _Description_: ‘SHIFTA’ returns a value corresponding to I with all of the bits shifted right by SHIFT places. SHIFT that be nonnegative and less than or equal to ‘BIT_SIZE(I)’, otherwise the result value is undefined. Bits shifted out from the right end are lost. The fill is arithmetic: the bits shifted in from the left end are equal to the leftmost bit, which in two's complement representation is the sign bit. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. SHIFT The type shall be ‘INTEGER’. _Return value_: The return value is of the same type and kind as I. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note SHIFTL::, *note SHIFTR::  File: gfortran.info, Node: SHIFTL, Next: SHIFTR, Prev: SHIFTA, Up: Intrinsic Procedures 8.248 ‘SHIFTL’ -- Left shift ============================ _Synopsis_: ‘RESULT = SHIFTL(I, SHIFT)’ _Description_: ‘SHIFTL’ returns a value corresponding to I with all of the bits shifted left by SHIFT places. SHIFT shall be nonnegative and less than or equal to ‘BIT_SIZE(I)’, otherwise the result value is undefined. Bits shifted out from the left end are lost, and bits shifted in from the right end are set to 0. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’ or ‘UNSIGNED’. SHIFT The type shall be ‘INTEGER’. _Return value_: The return value is of the same type and kind as I. _Standard_: Fortran 2008 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note SHIFTA::, *note SHIFTR::  File: gfortran.info, Node: SHIFTR, Next: SIGN, Prev: SHIFTL, Up: Intrinsic Procedures 8.249 ‘SHIFTR’ -- Right shift ============================= _Synopsis_: ‘RESULT = SHIFTR(I, SHIFT)’ _Description_: ‘SHIFTR’ returns a value corresponding to I with all of the bits shifted right by SHIFT places. SHIFT shall be nonnegative and less than or equal to ‘BIT_SIZE(I)’, otherwise the result value is undefined. Bits shifted out from the right end are lost, and bits shifted in from the left end are set to 0. _Class_: Elemental function _Arguments_: I The type shall be ‘INTEGER’. SHIFT The type shall be ‘INTEGER’. _Return value_: The return value is of type ‘INTEGER’ and of the same kind as I. _Standard_: Fortran 2008 and later _See also_: *note SHIFTA::, *note SHIFTL::  File: gfortran.info, Node: SIGN, Next: SIGNAL, Prev: SHIFTR, Up: Intrinsic Procedures 8.250 ‘SIGN’ -- Sign copying function ===================================== _Synopsis_: ‘RESULT = SIGN(A, B)’ _Description_: ‘SIGN(A,B)’ returns the value of A with the sign of B. _Class_: Elemental function _Arguments_: A Shall be of type ‘INTEGER’ or ‘REAL’ B Shall be of the same type and kind as A. _Return value_: The kind of the return value is that of A and B. If B \ge 0 then the result is ‘ABS(A)’, else it is ‘-ABS(A)’. _Example_: program test_sign print *, sign(-12,1) print *, sign(-12,0) print *, sign(-12,-1) print *, sign(-12.,1.) print *, sign(-12.,0.) print *, sign(-12.,-1.) end program test_sign _Specific names_: Name Arguments Return type Standard ------------------------------------------------------------------------- ‘SIGN(A,B)’ ‘REAL(4) A, B’ ‘REAL(4)’ Fortran 77 and later ‘ISIGN(A,B)’ ‘INTEGER(4) A, B’ ‘INTEGER(4)’ Fortran 77 and later ‘DSIGN(A,B)’ ‘REAL(8) A, B’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later  File: gfortran.info, Node: SIGNAL, Next: SIN, Prev: SIGN, Up: Intrinsic Procedures 8.251 ‘SIGNAL’ -- Signal handling subroutine (or function) ========================================================== _Synopsis_: ‘CALL SIGNAL(NUMBER, HANDLER [, STATUS])’ ‘STATUS = SIGNAL(NUMBER, HANDLER)’ _Description_: ‘SIGNAL(NUMBER, HANDLER [, STATUS])’ causes external subroutine HANDLER to be executed with a single integer argument passed by value when signal NUMBER occurs. If HANDLER is an integer, it can be used to turn off handling of signal NUMBER or revert to its default action. See ‘signal(2)’. If ‘SIGNAL’ is called as a subroutine and the STATUS argument is supplied, it is set to the value returned by ‘signal(2)’. _Class_: Subroutine, function _Arguments_: NUMBER Shall be a scalar integer, with ‘INTENT(IN)’ HANDLER Signal handler (‘INTEGER FUNCTION’ or ‘SUBROUTINE’) or dummy/global ‘INTEGER’ scalar. ‘INTEGER’. It is ‘INTENT(IN)’. STATUS (Optional) STATUS shall be a scalar integer. It has ‘INTENT(OUT)’. _Return value_: The ‘SIGNAL’ function returns the value returned by ‘signal(2)’. _Example_: module m_handler contains ! POSIX.1-2017: void (*func)(int) subroutine handler_print(signum) bind(C) use iso_c_binding, only: c_int integer(c_int), value :: signum print *, 'handler_print invoked with signum =', signum end subroutine end module program test_signal use m_handler intrinsic :: signal, sleep call signal (12, handler_print) ! 12 = SIGUSR2 (on some systems) call signal (10, 1) ! 10 = SIGUSR1 and 1 = SIG_IGN (on some systems) call sleep (30) end program test_signal _Standard_: GNU extension  File: gfortran.info, Node: SIN, Next: SIND, Prev: SIGNAL, Up: Intrinsic Procedures 8.252 ‘SIN’ -- Sine function ============================ _Synopsis_: ‘RESULT = SIN(X)’ _Description_: ‘SIN(X)’ computes the sine of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X. _Example_: program test_sin real :: x = 0.0 x = sin(x) end program test_sin _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘SIN(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DSIN(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later ‘CSIN(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ Fortran 77 and later ‘ZSIN(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDSIN(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 77 and later _See also_: Inverse function: *note ASIN:: Degrees function: *note SIND::  File: gfortran.info, Node: SIND, Next: SINH, Prev: SIN, Up: Intrinsic Procedures 8.253 ‘SIND’ -- Sine function, degrees ====================================== _Synopsis_: ‘RESULT = SIND(X)’ _Description_: ‘SIND(X)’ computes the sine of X in degrees. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value has same type and kind as X, and its value is in degrees. _Example_: program test_sind real :: x = 0.0 x = sind(x) end program test_sind _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘SIND(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 2023 ‘DSIND(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension ‘CSIND(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ GNU extension ‘ZSIND(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDSIND(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Inverse function: *note ASIND:: Radians function: *note SIN::  File: gfortran.info, Node: SINH, Next: SIZE, Prev: SIND, Up: Intrinsic Procedures 8.254 ‘SINH’ -- Hyperbolic sine function ======================================== _Synopsis_: ‘RESULT = SINH(X)’ _Description_: ‘SINH(X)’ computes the hyperbolic sine of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X. _Example_: program test_sinh real(8) :: x = - 1.0_8 x = sinh(x) end program test_sinh _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘DSINH(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 90 and later _Standard_: Fortran 90 and later, for a complex argument Fortran 2008 or later, has a GNU extension _See also_: *note ASINH::  File: gfortran.info, Node: SIZE, Next: SIZEOF, Prev: SINH, Up: Intrinsic Procedures 8.255 ‘SIZE’ -- Determine the size of an array ============================================== _Synopsis_: ‘RESULT = SIZE(ARRAY[, DIM [, KIND]])’ _Description_: Determine the extent of ARRAY along a specified dimension DIM, or the total number of elements in ARRAY if DIM is absent. _Class_: Inquiry function _Arguments_: ARRAY Shall be an array of any type. If ARRAY is a pointer it must be associated and allocatable arrays must be allocated. DIM (Optional) shall be a scalar of type ‘INTEGER’ and its value shall be in the range from 1 to n, where n equals the rank of ARRAY. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Example_: PROGRAM test_size WRITE(*,*) SIZE((/ 1, 2 /)) ! 2 END PROGRAM _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note SHAPE::, *note RESHAPE::  File: gfortran.info, Node: SIZEOF, Next: SLEEP, Prev: SIZE, Up: Intrinsic Procedures 8.256 ‘SIZEOF’ -- Size in bytes of an expression ================================================ _Synopsis_: ‘N = SIZEOF(X)’ _Description_: ‘SIZEOF(X)’ calculates the number of bytes of storage the expression ‘X’ occupies. _Class_: Inquiry function _Arguments_: X The argument shall be of any type, rank or shape. _Return value_: The return value is of type integer and of the system-dependent kind C_SIZE_T (from the ISO_C_BINDING module). Its value is the number of bytes occupied by the argument. If the argument has the ‘POINTER’ attribute, the number of bytes of the storage area pointed to is returned. If the argument is of a derived type with ‘POINTER’ or ‘ALLOCATABLE’ components, the return value does not account for the sizes of the data pointed to by these components. If the argument is polymorphic, the size according to the dynamic type is returned. The argument may not be a procedure or procedure pointer. Note that the code assumes for arrays that those are contiguous; for contiguous arrays, it returns the storage or an array element multiplied by the size of the array. _Example_: integer :: i real :: r, s(5) print *, (sizeof(s)/sizeof(r) == 5) end The example prints ‘.TRUE.’ unless you are using a platform where default ‘REAL’ variables are unusually padded. _Standard_: GNU extension _See also_: *note C_SIZEOF::, *note STORAGE_SIZE::  File: gfortran.info, Node: SLEEP, Next: SPACING, Prev: SIZEOF, Up: Intrinsic Procedures 8.257 ‘SLEEP’ -- Sleep for the specified number of seconds ========================================================== _Synopsis_: ‘CALL SLEEP(SECONDS)’ _Description_: Calling this subroutine causes the process to pause for SECONDS seconds. _Class_: Subroutine _Arguments_: SECONDS The type shall be of default ‘INTEGER’. _Example_: program test_sleep call sleep(5) end _Standard_: GNU extension  File: gfortran.info, Node: SPACING, Next: SPREAD, Prev: SLEEP, Up: Intrinsic Procedures 8.258 ‘SPACING’ -- Smallest distance between two numbers of a given type ======================================================================== _Synopsis_: ‘RESULT = SPACING(X)’ _Description_: Determines the distance between the argument X and the nearest adjacent number of the same type. _Class_: Elemental function _Arguments_: X Shall be of type ‘REAL’. _Return value_: The result is of the same type as the input argument X. _Example_: PROGRAM test_spacing INTEGER, PARAMETER :: SGL = SELECTED_REAL_KIND(p=6, r=37) INTEGER, PARAMETER :: DBL = SELECTED_REAL_KIND(p=13, r=200) WRITE(*,*) spacing(1.0_SGL) ! "1.1920929E-07" on i686 WRITE(*,*) spacing(1.0_DBL) ! "2.220446049250313E-016" on i686 END PROGRAM _Standard_: Fortran 90 and later _See also_: *note RRSPACING::  File: gfortran.info, Node: SPREAD, Next: SQRT, Prev: SPACING, Up: Intrinsic Procedures 8.259 ‘SPREAD’ -- Add a dimension to an array ============================================= _Synopsis_: ‘RESULT = SPREAD(SOURCE, DIM, NCOPIES)’ _Description_: Replicates a SOURCE array NCOPIES times along a specified dimension DIM. _Class_: Transformational function _Arguments_: SOURCE Shall be a scalar or an array of any type and a rank less than seven. DIM Shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n+1, where n equals the rank of SOURCE. NCOPIES Shall be a scalar of type ‘INTEGER’. _Return value_: The result is an array of the same type as SOURCE and has rank n+1 where n equals the rank of SOURCE. _Example_: PROGRAM test_spread INTEGER :: a = 1, b(2) = (/ 1, 2 /) WRITE(*,*) SPREAD(A, 1, 2) ! "1 1" WRITE(*,*) SPREAD(B, 1, 2) ! "1 1 2 2" END PROGRAM _Standard_: Fortran 90 and later _See also_: *note UNPACK::  File: gfortran.info, Node: SQRT, Next: SRAND, Prev: SPREAD, Up: Intrinsic Procedures 8.260 ‘SQRT’ -- Square-root function ==================================== _Synopsis_: ‘RESULT = SQRT(X)’ _Description_: ‘SQRT(X)’ computes the square root of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value is of type ‘REAL’ or ‘COMPLEX’. The kind type parameter is the same as X. _Example_: program test_sqrt real(8) :: x = 2.0_8 complex :: z = (1.0, 2.0) x = sqrt(x) z = sqrt(z) end program test_sqrt _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘SQRT(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DSQRT(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later ‘CSQRT(X)’ ‘COMPLEX(4) X’ ‘COMPLEX(4)’ Fortran 77 and later ‘ZSQRT(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension ‘CDSQRT(X)’ ‘COMPLEX(8) X’ ‘COMPLEX(8)’ GNU extension _Standard_: Fortran 77 and later  File: gfortran.info, Node: SRAND, Next: STAT, Prev: SQRT, Up: Intrinsic Procedures 8.261 ‘SRAND’ -- Reinitialize the random number generator ========================================================= _Synopsis_: ‘CALL SRAND(SEED)’ _Description_: ‘SRAND’ reinitializes the pseudo-random number generator called by ‘RAND’ and ‘IRAND’. The new seed used by the generator is specified by the required argument SEED. _Class_: Subroutine _Arguments_: SEED Shall be a scalar ‘INTEGER(kind=4)’. _Return value_: Does not return anything. _Example_: See ‘RAND’ and ‘IRAND’ for examples. _Notes_: The Fortran standard specifies the intrinsic subroutines ‘RANDOM_SEED’ to initialize the pseudo-random number generator and ‘RANDOM_NUMBER’ to generate pseudo-random numbers. These subroutines should be used in new codes. Please note that in GNU Fortran, these two sets of intrinsics (‘RAND’, ‘IRAND’ and ‘SRAND’ on the one hand, ‘RANDOM_NUMBER’ and ‘RANDOM_SEED’ on the other hand) access two independent pseudo-random number generators. _Standard_: GNU extension _See also_: *note RAND::, *note RANDOM_SEED::, *note RANDOM_NUMBER::  File: gfortran.info, Node: STAT, Next: STORAGE_SIZE, Prev: SRAND, Up: Intrinsic Procedures 8.262 ‘STAT’ -- Get file status =============================== _Synopsis_: ‘CALL STAT(NAME, VALUES [, STATUS])’ ‘STATUS = STAT(NAME, VALUES)’ _Description_: This function returns information about a file. No permissions are required on the file itself, but execute (search) permission is required on all of the directories in path that lead to the file. The elements that are obtained and stored in the array ‘VALUES’: ‘VALUES(1)’ Device ID ‘VALUES(2)’ Inode number ‘VALUES(3)’ File mode ‘VALUES(4)’ Number of links ‘VALUES(5)’ Owner's uid ‘VALUES(6)’ Owner's gid ‘VALUES(7)’ ID of device containing directory entry for file (0 if not available) ‘VALUES(8)’ File size (bytes) ‘VALUES(9)’ Last access time ‘VALUES(10)’Last modification time ‘VALUES(11)’Last file status change time ‘VALUES(12)’Preferred I/O block size (-1 if not available) ‘VALUES(13)’Number of blocks allocated (-1 if not available) Not all these elements are relevant on all systems. If an element is not relevant, it is returned as 0. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: NAME The type shall be ‘CHARACTER’, of the default kind and a valid path within the file system. VALUES The type shall be ‘INTEGER(4), DIMENSION(13)’. STATUS (Optional) status flag of type ‘INTEGER(4)’. Returns 0 on success and a system specific error code otherwise. _Example_: PROGRAM test_stat INTEGER, DIMENSION(13) :: buff INTEGER :: status CALL STAT("/etc/passwd", buff, status) IF (status == 0) THEN WRITE (*, FMT="('Device ID:', T30, I19)") buff(1) WRITE (*, FMT="('Inode number:', T30, I19)") buff(2) WRITE (*, FMT="('File mode (octal):', T30, O19)") buff(3) WRITE (*, FMT="('Number of links:', T30, I19)") buff(4) WRITE (*, FMT="('Owner''s uid:', T30, I19)") buff(5) WRITE (*, FMT="('Owner''s gid:', T30, I19)") buff(6) WRITE (*, FMT="('Device where located:', T30, I19)") buff(7) WRITE (*, FMT="('File size:', T30, I19)") buff(8) WRITE (*, FMT="('Last access time:', T30, A19)") CTIME(buff(9)) WRITE (*, FMT="('Last modification time', T30, A19)") CTIME(buff(10)) WRITE (*, FMT="('Last status change time:', T30, A19)") CTIME(buff(11)) WRITE (*, FMT="('Preferred block size:', T30, I19)") buff(12) WRITE (*, FMT="('No. of blocks allocated:', T30, I19)") buff(13) END IF END PROGRAM _Standard_: GNU extension _See also_: To stat an open file: *note FSTAT:: To stat a link: *note LSTAT::  File: gfortran.info, Node: STORAGE_SIZE, Next: SUM, Prev: STAT, Up: Intrinsic Procedures 8.263 ‘STORAGE_SIZE’ -- Storage size in bits ============================================ _Synopsis_: ‘RESULT = STORAGE_SIZE(A [, KIND])’ _Description_: Returns the storage size of argument A in bits. _Class_: Inquiry function _Arguments_: A Shall be a scalar or array of any type. KIND (Optional) shall be a scalar integer constant expression. _Return Value_: The result is a scalar integer with the kind type parameter specified by KIND (or default integer type if KIND is missing). The result value is the size expressed in bits for an element of an array that has the dynamic type and type parameters of A. _Standard_: Fortran 2008 and later _See also_: *note C_SIZEOF::, *note SIZEOF::  File: gfortran.info, Node: SUM, Next: SYMLNK, Prev: STORAGE_SIZE, Up: Intrinsic Procedures 8.264 ‘SUM’ -- Sum of array elements ==================================== _Synopsis_: ‘RESULT = SUM(ARRAY[, MASK])’ ‘RESULT = SUM(ARRAY, DIM[, MASK])’ _Description_: Adds the elements of ARRAY along dimension DIM if the corresponding element in MASK is ‘TRUE’. _Class_: Transformational function _Arguments_: ARRAY Shall be an array of type ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’. DIM (Optional) shall be a scalar of type ‘INTEGER’ with a value in the range from 1 to n, where n equals the rank of ARRAY. MASK (Optional) shall be of type ‘LOGICAL’ and either be a scalar or an array of the same shape as ARRAY. _Return value_: The result is of the same type as ARRAY. If DIM is absent, a scalar with the sum of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned. _Example_: PROGRAM test_sum INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /) print *, SUM(x) ! all elements, sum = 15 print *, SUM(x, MASK=MOD(x, 2)==1) ! odd elements, sum = 9 END PROGRAM _Standard_: Fortran 90 and later, extension for ‘UNSIGNED’ (*note Unsigned integers::) _See also_: *note PRODUCT::  File: gfortran.info, Node: SYMLNK, Next: SYSTEM, Prev: SUM, Up: Intrinsic Procedures 8.265 ‘SYMLNK’ -- Create a symbolic link ======================================== _Synopsis_: ‘CALL SYMLNK(PATH1, PATH2 [, STATUS])’ ‘STATUS = SYMLNK(PATH1, PATH2)’ _Description_: Makes a symbolic link from file PATH1 to PATH2. A null character (‘CHAR(0)’) can be used to mark the end of the names in PATH1 and PATH2; otherwise, trailing blanks in the file names are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see ‘symlink(2)’. If the system does not supply ‘symlink(2)’, ‘ENOSYS’ is returned. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: PATH1 Shall be of default ‘CHARACTER’ type. PATH2 Shall be of default ‘CHARACTER’ type. STATUS (Optional) Shall be of default ‘INTEGER’ type. _Standard_: GNU extension _See also_: *note LINK::, *note UNLINK::  File: gfortran.info, Node: SYSTEM, Next: SYSTEM_CLOCK, Prev: SYMLNK, Up: Intrinsic Procedures 8.266 ‘SYSTEM’ -- Execute a shell command ========================================= _Synopsis_: ‘CALL SYSTEM(COMMAND [, STATUS])’ ‘STATUS = SYSTEM(COMMAND)’ _Description_: Passes the command COMMAND to a shell (see ‘system(3)’). If argument STATUS is present, it contains the value returned by ‘system(3)’, which is presumably 0 if the shell command succeeded. Note that which shell is used to invoke the command is system-dependent and environment-dependent. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. Note that the ‘system’ function need not be thread-safe. It is the responsibility of the user to ensure that ‘system’ is not called concurrently. _Class_: Subroutine, function _Arguments_: COMMAND Shall be of default ‘CHARACTER’ type. STATUS (Optional) Shall be of default ‘INTEGER’ type. _Standard_: GNU extension _See also_: *note EXECUTE_COMMAND_LINE::, which is part of the Fortran 2008 standard and should considered in new code for future portability.  File: gfortran.info, Node: SYSTEM_CLOCK, Next: TAN, Prev: SYSTEM, Up: Intrinsic Procedures 8.267 ‘SYSTEM_CLOCK’ -- Time function ===================================== _Synopsis_: ‘CALL SYSTEM_CLOCK([COUNT, COUNT_RATE, COUNT_MAX])’ _Description_: Determines the COUNT of a processor clock since an unspecified time in the past modulo COUNT_MAX, COUNT_RATE determines the number of clock ticks per second. If the platform supports a monotonic clock, that clock is used and can, depending on the platform clock implementation, provide up to nanosecond resolution. If a monotonic clock is not available, the implementation falls back to a realtime clock. COUNT_RATE is system dependent and can vary depending on the kind of the arguments. For KIND=4 arguments (and smaller integer kinds), COUNT represents milliseconds, while for KIND=8 arguments (and larger integer kinds), COUNT typically represents micro- or nanoseconds depending on resolution of the underlying platform clock. COUNT_MAX usually equals ‘HUGE(COUNT_MAX)’. Note that the millisecond resolution of the KIND=4 version implies that the COUNT wraps around in roughly 25 days. In order to avoid issues with the wrap-around and for more precise timing, please use the KIND=8 version. If there is no clock, or querying the clock fails, COUNT is set to ‘-HUGE(COUNT)’, and COUNT_RATE and COUNT_MAX are set to zero. When running on a platform using the GNU C library (glibc) version 2.16 or older, or a derivative thereof, the high resolution monotonic clock is available only when linking with the RT library. This can be done explicitly by adding the ‘-lrt’ flag when linking the application, but is also done implicitly when using OpenMP. On the Windows platform, the version with KIND=4 arguments uses the ‘GetTickCount’ function, whereas the KIND=8 version uses ‘QueryPerformanceCounter’ and ‘QueryPerformanceCounterFrequency’. For more information, and potential caveats, please see the platform documentation. _Class_: Subroutine _Arguments_: COUNT (Optional) shall be a scalar of type ‘INTEGER’ with ‘INTENT(OUT)’. COUNT_RATE (Optional) shall be a scalar of type ‘INTEGER’ or ‘REAL’, with ‘INTENT(OUT)’. COUNT_MAX (Optional) shall be a scalar of type ‘INTEGER’ with ‘INTENT(OUT)’. _Example_: PROGRAM test_system_clock INTEGER :: count, count_rate, count_max CALL SYSTEM_CLOCK(count, count_rate, count_max) WRITE(*,*) count, count_rate, count_max END PROGRAM _Standard_: Fortran 90 and later _See also_: *note DATE_AND_TIME::, *note CPU_TIME::  File: gfortran.info, Node: TAN, Next: TAND, Prev: SYSTEM_CLOCK, Up: Intrinsic Procedures 8.268 ‘TAN’ -- Tangent function =============================== _Synopsis_: ‘RESULT = TAN(X)’ _Description_: ‘TAN(X)’ computes the tangent of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X, and its value is in radians. _Example_: program test_tan real(8) :: x = 0.165_8 x = tan(x) end program test_tan _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘TAN(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DTAN(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, for a complex argument Fortran 2008 or later _See also_: Inverse function: *note ATAN:: Degrees function: *note TAND::  File: gfortran.info, Node: TAND, Next: TANH, Prev: TAN, Up: Intrinsic Procedures 8.269 ‘TAND’ -- Tangent function, degrees ========================================= _Synopsis_: ‘RESULT = TAND(X)’ _Description_: ‘TAND(X)’ computes the tangent of X in degrees. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’. _Return value_: The return value has same type and kind as X. _Example_: program test_tand real(8) :: x = 45_8 x = tand(x) end program test_tand _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘TAND(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 2023 ‘DTAND(X)’ ‘REAL(8) X’ ‘REAL(8)’ GNU extension _Standard_: Fortran 2023 _See also_: Inverse function: *note ATAND:: Radians function: *note TAN::  File: gfortran.info, Node: TANH, Next: THIS_IMAGE, Prev: TAND, Up: Intrinsic Procedures 8.270 ‘TANH’ -- Hyperbolic tangent function =========================================== _Synopsis_: ‘X = TANH(X)’ _Description_: ‘TANH(X)’ computes the hyperbolic tangent of X. _Class_: Elemental function _Arguments_: X The type shall be ‘REAL’ or ‘COMPLEX’. _Return value_: The return value has same type and kind as X. If X is complex, the imaginary part of the result is in radians. If X is ‘REAL’, the return value lies in the range - 1 \leq tanh(x) \leq 1 . _Example_: program test_tanh real(8) :: x = 2.1_8 x = tanh(x) end program test_tanh _Specific names_: Name Argument Return type Standard ------------------------------------------------------------------------- ‘TANH(X)’ ‘REAL(4) X’ ‘REAL(4)’ Fortran 77 and later ‘DTANH(X)’ ‘REAL(8) X’ ‘REAL(8)’ Fortran 77 and later _Standard_: Fortran 77 and later, for a complex argument Fortran 2008 or later _See also_: *note ATANH::  File: gfortran.info, Node: THIS_IMAGE, Next: TIME, Prev: TANH, Up: Intrinsic Procedures 8.271 ‘THIS_IMAGE’ -- Function that returns the cosubscript index of this image =============================================================================== _Synopsis_: ‘RESULT = THIS_IMAGE()’ ‘RESULT = THIS_IMAGE(DISTANCE)’ ‘RESULT = THIS_IMAGE(COARRAY [, DIM])’ _Description_: Returns the cosubscript for this image. _Class_: Transformational function _Arguments_: DISTANCE (optional, intent(in)) Nonnegative scalar integer (not permitted together with COARRAY). COARRAY Coarray of any type (optional; if DIM present, required). DIM default integer scalar (optional). If present, DIM shall be between one and the corank of COARRAY. _Return value_: Default integer. If COARRAY is not present, it is scalar; if DISTANCE is not present or has value 0, its value is the image index on the invoking image for the current team, for values smaller or equal distance to the initial team, it returns the image index on the ancestor team that has a distance of DISTANCE from the invoking team. If DISTANCE is larger than the distance to the initial team, the image index of the initial team is returned. Otherwise when the COARRAY is present, if DIM is not present, a rank-1 array with corank elements is returned, containing the cosubscripts for COARRAY specifying the invoking image. If DIM is present, a scalar is returned, with the value of the DIM element of ‘THIS_IMAGE(COARRAY)’. _Example_: INTEGER :: value[*] INTEGER :: i value = THIS_IMAGE() SYNC ALL IF (THIS_IMAGE() == 1) THEN DO i = 1, NUM_IMAGES() WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i] END DO END IF ! Check whether the current image is the initial image IF (THIS_IMAGE(HUGE(1)) /= THIS_IMAGE()) error stop "something is rotten here" _Standard_: Fortran 2008 and later. With DISTANCE argument, Technical Specification (TS) 18508 or later _See also_: *note NUM_IMAGES::, *note IMAGE_INDEX::  File: gfortran.info, Node: TIME, Next: TIME8, Prev: THIS_IMAGE, Up: Intrinsic Procedures 8.272 ‘TIME’ -- Time function ============================= _Synopsis_: ‘RESULT = TIME()’ _Description_: Returns the current time encoded as an integer (in the manner of the function ‘time(3)’ in the C standard library). This value is suitable for passing to *note CTIME::, *note GMTIME::, and *note LTIME::. This intrinsic is not fully portable, such as to systems with 32-bit ‘INTEGER’ types but supporting times wider than 32 bits. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program. See *note TIME8::, for information on a similar intrinsic that might be portable to more GNU Fortran implementations, though to fewer Fortran compilers. _Class_: Function _Return value_: The return value is a scalar of type ‘INTEGER(4)’. _Standard_: GNU extension _See also_: *note DATE_AND_TIME::, *note CTIME::, *note GMTIME::, *note LTIME::, *note MCLOCK::, *note TIME8::  File: gfortran.info, Node: TIME8, Next: TINY, Prev: TIME, Up: Intrinsic Procedures 8.273 ‘TIME8’ -- Time function (64-bit) ======================================= _Synopsis_: ‘RESULT = TIME8()’ _Description_: Returns the current time encoded as an integer (in the manner of the function ‘time(3)’ in the C standard library). This value is suitable for passing to *note CTIME::, *note GMTIME::, and *note LTIME::. _Warning:_ this intrinsic does not increase the range of the timing values over that returned by ‘time(3)’. On a system with a 32-bit ‘time(3)’, ‘TIME8’ returns a 32-bit value, even though it is converted to a 64-bit ‘INTEGER(8)’ value. That means overflows of the 32-bit value can still occur. Therefore, the values returned by this intrinsic might be or become negative or numerically less than previous values during a single run of the compiled program. _Class_: Function _Return value_: The return value is a scalar of type ‘INTEGER(8)’. _Standard_: GNU extension _See also_: *note DATE_AND_TIME::, *note CTIME::, *note GMTIME::, *note LTIME::, *note MCLOCK8::, *note TIME::  File: gfortran.info, Node: TINY, Next: TRAILZ, Prev: TIME8, Up: Intrinsic Procedures 8.274 ‘TINY’ -- Smallest positive number of a real kind ======================================================= _Synopsis_: ‘RESULT = TINY(X)’ _Description_: ‘TINY(X)’ returns the smallest positive (non zero) number in the model of the type of ‘X’. _Class_: Inquiry function _Arguments_: X Shall be of type ‘REAL’. _Return value_: The return value is of the same type and kind as X _Example_: See ‘HUGE’ for an example. _Standard_: Fortran 90 and later  File: gfortran.info, Node: TRAILZ, Next: TRANSFER, Prev: TINY, Up: Intrinsic Procedures 8.275 ‘TRAILZ’ -- Number of trailing zero bits of an integer ============================================================ _Synopsis_: ‘RESULT = TRAILZ(I)’ _Description_: ‘TRAILZ’ returns the number of trailing zero bits of an integer. _Class_: Elemental function _Arguments_: I Shall be of type ‘INTEGER’. _Return value_: The type of the return value is the default ‘INTEGER’. If all the bits of ‘I’ are zero, the result value is ‘BIT_SIZE(I)’. _Example_: PROGRAM test_trailz WRITE (*,*) TRAILZ(8) ! prints 3 END PROGRAM _Standard_: Fortran 2008 and later _See also_: *note BIT_SIZE::, *note LEADZ::, *note POPPAR::, *note POPCNT::  File: gfortran.info, Node: TRANSFER, Next: TRANSPOSE, Prev: TRAILZ, Up: Intrinsic Procedures 8.276 ‘TRANSFER’ -- Transfer bit patterns ========================================= _Synopsis_: ‘RESULT = TRANSFER(SOURCE, MOLD[, SIZE])’ _Description_: Interprets the bitwise representation of SOURCE in memory as if it is the representation of a variable or array of the same type and type parameters as MOLD. This is approximately equivalent to the C concept of _casting_ one type to another. _Class_: Transformational function _Arguments_: SOURCE Shall be a scalar or an array of any type. MOLD Shall be a scalar or an array of any type. SIZE (Optional) shall be a scalar of type ‘INTEGER’. _Return value_: The result has the same type as MOLD, with the bit level representation of SOURCE. If SIZE is present, the result is a one-dimensional array of length SIZE. If SIZE is absent but MOLD is an array (of any size or shape), the result is a one- dimensional array of the minimum length needed to contain the entirety of the bitwise representation of SOURCE. If SIZE is absent and MOLD is a scalar, the result is a scalar. If the bitwise representation of the result is longer than that of SOURCE, then the leading bits of the result correspond to those of SOURCE and any trailing bits are filled arbitrarily. When the resulting bit representation does not correspond to a valid representation of a variable of the same type as MOLD, the results are undefined, and subsequent operations on the result cannot be guaranteed to produce sensible behavior. For example, it is possible to create ‘LOGICAL’ variables for which ‘VAR’ and ‘.NOT.VAR’ both appear to be true. _Example_: PROGRAM test_transfer integer :: x = 2143289344 print *, transfer(x, 1.0) ! prints "NaN" on i686 END PROGRAM _Standard_: Fortran 90 and later  File: gfortran.info, Node: TRANSPOSE, Next: TRIM, Prev: TRANSFER, Up: Intrinsic Procedures 8.277 ‘TRANSPOSE’ -- Transpose an array of rank two =================================================== _Synopsis_: ‘RESULT = TRANSPOSE(MATRIX)’ _Description_: Transpose an array of rank two. Element (i, j) of the result has the value ‘MATRIX(j, i)’, for all i, j. _Class_: Transformational function _Arguments_: MATRIX Shall be an array of any type and have a rank of two. _Return value_: The result has the same type as MATRIX, and has shape ‘(/ m, n /)’ if MATRIX has shape ‘(/ n, m /)’. _Standard_: Fortran 90 and later  File: gfortran.info, Node: TRIM, Next: TTYNAM, Prev: TRANSPOSE, Up: Intrinsic Procedures 8.278 ‘TRIM’ -- Remove trailing blank characters of a string ============================================================ _Synopsis_: ‘RESULT = TRIM(STRING)’ _Description_: Removes trailing blank characters of a string. _Class_: Transformational function _Arguments_: STRING Shall be a scalar of type ‘CHARACTER’. _Return value_: A scalar of type ‘CHARACTER’ that is the length of STRING less the number of trailing blanks. _Example_: PROGRAM test_trim CHARACTER(len=10), PARAMETER :: s = "GFORTRAN " WRITE(*,*) LEN(s), LEN(TRIM(s)) ! "10 8", with/without trailing blanks END PROGRAM _Standard_: Fortran 90 and later _See also_: *note ADJUSTL::, *note ADJUSTR::  File: gfortran.info, Node: TTYNAM, Next: UBOUND, Prev: TRIM, Up: Intrinsic Procedures 8.279 ‘TTYNAM’ -- Get the name of a terminal device =================================================== _Synopsis_: ‘CALL TTYNAM(UNIT, NAME)’ ‘NAME = TTYNAM(UNIT)’ _Description_: Get the name of a terminal device. For more information, see ‘ttyname(3)’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: UNIT Shall be a scalar ‘INTEGER’. NAME Shall be of type ‘CHARACTER’. _Example_: PROGRAM test_ttynam INTEGER :: unit DO unit = 1, 10 IF (isatty(unit=unit)) write(*,*) ttynam(unit) END DO END PROGRAM _Standard_: GNU extension _See also_: *note ISATTY::  File: gfortran.info, Node: UBOUND, Next: UCOBOUND, Prev: TTYNAM, Up: Intrinsic Procedures 8.280 ‘UBOUND’ -- Upper dimension bounds of an array ==================================================== _Synopsis_: ‘RESULT = UBOUND(ARRAY [, DIM [, KIND]])’ _Description_: Returns the upper bounds of an array, or a single upper bound along the DIM dimension. _Class_: Inquiry function _Arguments_: ARRAY Shall be an array, of any type. DIM (Optional) Shall be a scalar ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is absent, the result is an array of the upper bounds of ARRAY. If DIM is present, the result is a scalar corresponding to the upper bound of the array along that dimension. If ARRAY is an expression rather than a whole array or array structure component, or if it has a zero extent along the relevant dimension, the upper bound is taken to be the number of elements along the relevant dimension. _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note LBOUND::, *note LCOBOUND::  File: gfortran.info, Node: UCOBOUND, Next: UINT, Prev: UBOUND, Up: Intrinsic Procedures 8.281 ‘UCOBOUND’ -- Upper codimension bounds of an array ======================================================== _Synopsis_: ‘RESULT = UCOBOUND(COARRAY [, DIM [, KIND]])’ _Description_: Returns the upper cobounds of a coarray, or a single upper cobound along the DIM codimension. _Class_: Inquiry function _Arguments_: ARRAY Shall be an coarray, of any type. DIM (Optional) Shall be a scalar ‘INTEGER’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. If DIM is absent, the result is an array of the lower cobounds of COARRAY. If DIM is present, the result is a scalar corresponding to the lower cobound of the array along that codimension. _Standard_: Fortran 2008 and later _See also_: *note LCOBOUND::, *note LBOUND::  File: gfortran.info, Node: UINT, Next: UMASK, Prev: UCOBOUND, Up: Intrinsic Procedures 8.282 ‘UINT’ - Convert to ‘UNSIGNED’ type ========================================= _Synopsis_: ‘RESULT = UINT(A [, KIND))’ _Description_: Convert to unsigned type _Class_: Elemental function _Arguments_: A Shall be of type ‘INTEGER’, ‘REAL’, ‘COMPLEX’ or ‘UNSIGNED’ or a boz-literal-constant. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Standard_: Extension.  File: gfortran.info, Node: UMASK, Next: UMASKL, Prev: UINT, Up: Intrinsic Procedures 8.283 ‘UMASK’ -- Set the file creation mask =========================================== _Synopsis_: ‘CALL UMASK(MASK [, OLD])’ ‘OLD = UMASK(MASK)’ _Description_: Sets the file creation mask to MASK. If called as a function, it returns the old value. If called as a subroutine and argument OLD if it is supplied, it is set to the old value. See ‘umask(2)’. _Class_: Subroutine, function _Arguments_: MASK Shall be a scalar of type ‘INTEGER’. OLD (Optional) Shall be a scalar of type ‘INTEGER’. _Standard_: GNU extension  File: gfortran.info, Node: UMASKL, Next: UMASKR, Prev: UMASK, Up: Intrinsic Procedures 8.284 ‘UMASKL’ -- Unsigned left justified mask ============================================== _Synopsis_: ‘RESULT = UMASKL(I[, KIND])’ _Description_: ‘UMASKL(I[, KIND])’ has its leftmost I bits set to 1, and the remaining bits set to 0. _Class_: Elemental function _Arguments_: I Shall be of type ‘UNSIGNED’. KIND Shall be a scalar constant expression of type ‘INTEGER’. _Return value_: The return value is of type ‘UNSIGNED’. If KIND is present, it specifies the kind value of the return type; otherwise, it is of the default unsigned kind. _Standard_: Extension (*note Unsigned integers::) _See also_: *note MASKL::, *note MASKR::, *note UMASKR::  File: gfortran.info, Node: UMASKR, Next: UNLINK, Prev: UMASKL, Up: Intrinsic Procedures 8.285 ‘UMASKR’ -- Unsigned right justified mask =============================================== _Synopsis_: ‘RESULT = MASKR(I[, KIND])’ _Description_: ‘UMASKL(I[, KIND])’ has its rightmost I bits set to 1, and the remaining bits set to 0. _Class_: Elemental function _Arguments_: I Shall be of type ‘UNSIGNED’. KIND Shall be a scalar constant expression of type ‘INTEGER’. _Return value_: The return value is of type ‘UNSIGNED’. If KIND is present, it specifies the kind value of the return type; otherwise, it is of the default integer kind. _Standard_: Extension (*note Unsigned integers::) _See also_: *note MASKL::, *note MASKR::, *note UMASKL::  File: gfortran.info, Node: UNLINK, Next: UNPACK, Prev: UMASKR, Up: Intrinsic Procedures 8.286 ‘UNLINK’ -- Remove a file from the file system ==================================================== _Synopsis_: ‘CALL UNLINK(PATH [, STATUS])’ ‘STATUS = UNLINK(PATH)’ _Description_: Unlinks the file PATH. A null character (‘CHAR(0)’) can be used to mark the end of the name in PATH; otherwise, trailing blanks in the file name are ignored. If the STATUS argument is supplied, it contains 0 on success or a nonzero error code upon return; see ‘unlink(2)’. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. _Class_: Subroutine, function _Arguments_: PATH Shall be of default ‘CHARACTER’ type. STATUS (Optional) Shall be of default ‘INTEGER’ type. _Standard_: GNU extension _See also_: *note LINK::, *note SYMLNK::  File: gfortran.info, Node: UNPACK, Next: VERIFY, Prev: UNLINK, Up: Intrinsic Procedures 8.287 ‘UNPACK’ -- Unpack an array of rank one into an array =========================================================== _Synopsis_: ‘RESULT = UNPACK(VECTOR, MASK, FIELD)’ _Description_: Store the elements of VECTOR in an array of higher rank. _Class_: Transformational function _Arguments_: VECTOR Shall be an array of any type and rank one. It shall have at least as many elements as MASK has ‘TRUE’ values. MASK Shall be an array of type ‘LOGICAL’. FIELD Shall be of the same type as VECTOR and have the same shape as MASK. _Return value_: The resulting array corresponds to FIELD with ‘TRUE’ elements of MASK replaced by values from VECTOR in array element order. _Example_: PROGRAM test_unpack integer :: vector(2) = (/1,1/) logical :: mask(4) = (/ .TRUE., .FALSE., .FALSE., .TRUE. /) integer :: field(2,2) = 0, unity(2,2) ! result: unity matrix unity = unpack(vector, reshape(mask, (/2,2/)), field) END PROGRAM _Standard_: Fortran 90 and later _See also_: *note PACK::, *note SPREAD::  File: gfortran.info, Node: VERIFY, Next: XOR, Prev: UNPACK, Up: Intrinsic Procedures 8.288 ‘VERIFY’ -- Scan a string for characters not a given set ============================================================== _Synopsis_: ‘RESULT = VERIFY(STRING, SET[, BACK [, KIND]])’ _Description_: Verifies that all the characters in STRING belong to the set of characters in SET. If BACK is either absent or equals ‘FALSE’, this function returns the position of the leftmost character of STRING that is not in SET. If BACK equals ‘TRUE’, the rightmost position is returned. If all characters of STRING are found in SET, the result is zero. _Class_: Elemental function _Arguments_: STRING Shall be of type ‘CHARACTER’. SET Shall be of type ‘CHARACTER’. BACK (Optional) shall be of type ‘LOGICAL’. KIND (Optional) A scalar ‘INTEGER’ constant expression indicating the kind parameter of the result. _Return value_: The return value is of type ‘INTEGER’ and of kind KIND. If KIND is absent, the return value is of default integer kind. _Example_: PROGRAM test_verify WRITE(*,*) VERIFY("FORTRAN", "AO") ! 1, found 'F' WRITE(*,*) VERIFY("FORTRAN", "FOO") ! 3, found 'R' WRITE(*,*) VERIFY("FORTRAN", "C++") ! 1, found 'F' WRITE(*,*) VERIFY("FORTRAN", "C++", .TRUE.) ! 7, found 'N' WRITE(*,*) VERIFY("FORTRAN", "FORTRAN") ! 0' found none END PROGRAM _Standard_: Fortran 90 and later, with KIND argument Fortran 2003 and later _See also_: *note SCAN::, *note INDEX intrinsic::  File: gfortran.info, Node: XOR, Prev: VERIFY, Up: Intrinsic Procedures 8.289 ‘XOR’ -- Bitwise logical exclusive OR =========================================== _Synopsis_: ‘RESULT = XOR(I, J)’ _Description_: Bitwise logical exclusive or. This intrinsic routine is provided for backwards compatibility with GNU Fortran 77. For integer arguments, programmers should consider the use of the *note IEOR:: intrinsic and for logical arguments the ‘.NEQV.’ operator, which are both defined by the Fortran standard. _Class_: Function _Arguments_: I The type shall be either a scalar ‘INTEGER’ type or a scalar ‘LOGICAL’ type or a boz-literal-constant. J The type shall be the same as the type of I or a boz-literal-constant. I and J shall not both be boz-literal-constants. If either I and J is a boz-literal-constant, then the other argument must be a scalar ‘INTEGER’. _Return value_: The return type is either a scalar ‘INTEGER’ or a scalar ‘LOGICAL’. If the kind type parameters differ, then the smaller kind type is implicitly converted to larger kind, and the return has the larger kind. A boz-literal-constant is converted to an ‘INTEGER’ with the kind type parameter of the other argument as-if a call to *note INT:: occurred. _Example_: PROGRAM test_xor LOGICAL :: T = .TRUE., F = .FALSE. INTEGER :: a, b DATA a / Z'F' /, b / Z'3' / WRITE (*,*) XOR(T, T), XOR(T, F), XOR(F, T), XOR(F, F) WRITE (*,*) XOR(a, b) END PROGRAM _Standard_: GNU extension _See also_: Fortran 95 elemental function: *note IEOR::  File: gfortran.info, Node: Intrinsic Modules, Next: Contributing, Prev: Intrinsic Procedures, Up: Top 9 Intrinsic Modules ******************* * Menu: * ISO_FORTRAN_ENV:: * ISO_C_BINDING:: * IEEE modules:: * OpenMP Modules OMP_LIB and OMP_LIB_KINDS:: * OpenACC Module OPENACC::  File: gfortran.info, Node: ISO_FORTRAN_ENV, Next: ISO_C_BINDING, Up: Intrinsic Modules 9.1 ‘ISO_FORTRAN_ENV’ ===================== _Standard_: Fortran 2003 and later, except when otherwise noted The ‘ISO_FORTRAN_ENV’ module provides the following scalar default-integer named constants: ‘ATOMIC_INT_KIND’: Default-kind integer constant to be used as kind parameter when defining integer variables used in atomic operations. (Fortran 2008 or later.) ‘ATOMIC_LOGICAL_KIND’: Default-kind integer constant to be used as kind parameter when defining logical variables used in atomic operations. (Fortran 2008 or later.) ‘CHARACTER_KINDS’: Default-kind integer constant array of rank one containing the supported kind parameters of the ‘CHARACTER’ type. (Fortran 2008 or later.) ‘CHARACTER_STORAGE_SIZE’: Size in bits of the character storage unit. ‘ERROR_UNIT’: Identifies the preconnected unit used for error reporting. ‘FILE_STORAGE_SIZE’: Size in bits of the file-storage unit. ‘INPUT_UNIT’: Identifies the preconnected unit identified by the asterisk (‘*’) in ‘READ’ statement. ‘INT8’, ‘INT16’, ‘INT32’, ‘INT64’: Kind type parameters to specify an INTEGER type with a storage size of 8, 16, 32, and 64 bits. It is negative if a target platform does not support the particular kind. (Fortran 2008 or later.) ‘INTEGER_KINDS’: Default-kind integer constant array of rank one containing the supported kind parameters of the ‘INTEGER’ type. (Fortran 2008 or later.) ‘IOSTAT_END’: The value assigned to the variable passed to the ‘IOSTAT=’ specifier of an input/output statement if an end-of-file condition occurred. ‘IOSTAT_EOR’: The value assigned to the variable passed to the ‘IOSTAT=’ specifier of an input/output statement if an end-of-record condition occurred. ‘IOSTAT_INQUIRE_INTERNAL_UNIT’: Scalar default-integer constant, used by ‘INQUIRE’ for the ‘IOSTAT=’ specifier to denote an that a unit number identifies an internal unit. (Fortran 2008 or later.) ‘NUMERIC_STORAGE_SIZE’: The size in bits of the numeric storage unit. ‘LOGICAL_KINDS’: Default-kind integer constant array of rank one containing the supported kind parameters of the ‘LOGICAL’ type. (Fortran 2008 or later.) ‘OUTPUT_UNIT’: Identifies the preconnected unit identified by the asterisk (‘*’) in ‘WRITE’ statement. ‘REAL32’, ‘REAL64’, ‘REAL128’: Kind type parameters to specify a REAL type with a storage size of 32, 64, and 128 bits. It is negative if a target platform does not support the particular kind. (Fortran 2008 or later.) ‘REAL_KINDS’: Default-kind integer constant array of rank one containing the supported kind parameters of the ‘REAL’ type. (Fortran 2008 or later.) ‘STAT_LOCKED’: Scalar default-integer constant used as ‘STAT=’ return value by ‘LOCK’ to denote that the lock variable is locked by the executing image. (Fortran 2008 or later.) ‘STAT_LOCKED_OTHER_IMAGE’: Scalar default-integer constant used as ‘STAT=’ return value by ‘UNLOCK’ to denote that the lock variable is locked by another image. (Fortran 2008 or later.) ‘STAT_STOPPED_IMAGE’: Positive, scalar default-integer constant used as ‘STAT=’ return value if the argument in the statement requires synchronization with an image that has initiated termination. (Fortran 2008 or later.) ‘STAT_FAILED_IMAGE’: Positive, scalar default-integer constant used as ‘STAT=’ return value if the argument in the statement requires communication with an image that is in the failed state. (TS 18508 or later.) ‘STAT_UNLOCKED’: Scalar default-integer constant used as ‘STAT=’ return value by ‘UNLOCK’ to denote that the lock variable is unlocked. (Fortran 2008 or later.) ‘UINT8’, ‘UINT16’, ‘UINT32’, ‘UINT64’: Kind type parameters to specify an UNSIGNED type with a storage size of 8, 16, 32, and 64 bits. It is negative if a target platform does not support the particular kind. (Extension, *note Unsigned integers::.) The module provides the following derived type: ‘LOCK_TYPE’: Derived type with private components to be use with the ‘LOCK’ and ‘UNLOCK’ statement. A variable of its type has to be always declared as coarray and may not appear in a variable-definition context. (Fortran 2008 or later.) The module also provides the following intrinsic procedures: *note COMPILER_OPTIONS:: and *note COMPILER_VERSION::.  File: gfortran.info, Node: ISO_C_BINDING, Next: IEEE modules, Prev: ISO_FORTRAN_ENV, Up: Intrinsic Modules 9.2 ‘ISO_C_BINDING’ =================== _Standard_: Fortran 2003 and later, GNU extensions The following intrinsic procedures are provided by the module; their definition can be found in the section Intrinsic Procedures of this manual. ‘C_ASSOCIATED’ ‘C_F_POINTER’ ‘C_F_PROCPOINTER’ ‘C_FUNLOC’ ‘C_LOC’ ‘C_SIZEOF’ The ‘ISO_C_BINDING’ module provides the following named constants of type default integer, which can be used as KIND type parameters. In addition to the integer named constants required by the Fortran 2003 standard and ‘C_PTRDIFF_T’ of TS 29113, GNU Fortran provides as an extension named constants for the 128-bit integer types supported by the C compiler: ‘C_INT128_T, C_INT_LEAST128_T, C_INT_FAST128_T’. Furthermore, if ‘_Float128’ is supported in C, the named constants ‘C_FLOAT128’ and ‘C_FLOAT128_COMPLEX’ are defined. Fortran Type Named constant C type Extension ---------------------------------------------------------------------------- ‘INTEGER’ ‘C_INT’ ‘int’ ‘INTEGER’ ‘C_SHORT’ ‘short int’ ‘INTEGER’ ‘C_LONG’ ‘long int’ ‘INTEGER’ ‘C_LONG_LONG’ ‘long long int’ ‘INTEGER’ ‘C_SIGNED_CHAR’ ‘signed char’/‘unsigned char’ ‘INTEGER’ ‘C_SIZE_T’ ‘size_t’ ‘INTEGER’ ‘C_INT8_T’ ‘int8_t’ ‘INTEGER’ ‘C_INT16_T’ ‘int16_t’ ‘INTEGER’ ‘C_INT32_T’ ‘int32_t’ ‘INTEGER’ ‘C_INT64_T’ ‘int64_t’ ‘INTEGER’ ‘C_INT128_T’ ‘int128_t’ Ext. ‘INTEGER’ ‘C_INT_LEAST8_T’ ‘int_least8_t’ ‘INTEGER’ ‘C_INT_LEAST16_T’ ‘int_least16_t’ ‘INTEGER’ ‘C_INT_LEAST32_T’ ‘int_least32_t’ ‘INTEGER’ ‘C_INT_LEAST64_T’ ‘int_least64_t’ ‘INTEGER’ ‘C_INT_LEAST128_T’ ‘int_least128_t’ Ext. ‘INTEGER’ ‘C_INT_FAST8_T’ ‘int_fast8_t’ ‘INTEGER’ ‘C_INT_FAST16_T’ ‘int_fast16_t’ ‘INTEGER’ ‘C_INT_FAST32_T’ ‘int_fast32_t’ ‘INTEGER’ ‘C_INT_FAST64_T’ ‘int_fast64_t’ ‘INTEGER’ ‘C_INT_FAST128_T’ ‘int_fast128_t’ Ext. ‘INTEGER’ ‘C_INTMAX_T’ ‘intmax_t’ ‘INTEGER’ ‘C_INTPTR_T’ ‘intptr_t’ ‘INTEGER’ ‘C_PTRDIFF_T’ ‘ptrdiff_t’ TS 29113 ‘REAL’ ‘C_FLOAT’ ‘float’ ‘REAL’ ‘C_DOUBLE’ ‘double’ ‘REAL’ ‘C_LONG_DOUBLE’ ‘long double’ ‘REAL’ ‘C_FLOAT128’ ‘_Float128’ Ext. ‘COMPLEX’ ‘C_FLOAT_COMPLEX’ ‘float _Complex’ ‘COMPLEX’ ‘C_DOUBLE_COMPLEX’ ‘double _Complex’ ‘COMPLEX’ ‘C_LONG_DOUBLE_COMPLEX’ ‘long double _Complex’ ‘COMPLEX’ ‘C_FLOAT128_COMPLEX’ ‘_Float128 _Complex’ Ext. ‘LOGICAL’ ‘C_BOOL’ ‘_Bool’ ‘CHARACTER’ ‘C_CHAR’ ‘char’ GNU Fortran also provides as an extension, named constants for ‘UNSIGNED’ integers *note Unsigned integers::. Fortran Type Named constant C type --------------------------------------------------------------------------- ‘UNSIGNED’ ‘C_UNSIGNED’ ‘unsigned int’ ‘UNSIGNED’ ‘C_UNSIGNED_SHORT’ ‘unsigned short’ ‘UNSIGNED’ ‘C_UNSIGNED_CHAR’ ‘unsigned char’ ‘UNSINGED’ ‘C_UNSIGNED_LONG’ ‘unsigned long’ ‘UNSINGED’ ‘C_UNSIGNED_LONG_LONG’ ‘unsigned long long’ ‘UNSIGNED’ ‘C_UINTMAX_T’ ‘uintmax_t’ ‘UNSIGNED’ ‘C_UINT8_T’ ‘uint8_t’ ‘UNSIGNED’ ‘C_UINT16_T’ ‘uint16_t’ ‘UNSIGNED’ ‘C_UINT32_T’ ‘uint32_t’ ‘UNSIGNED’ ‘C_UINT64_T’ ‘uint64_t’ ‘UNSIGNED’ ‘C_UINT128_T’ ‘uint128_t’ ‘UNSIGNED’ ‘C_UINT_FAST8_T’ ‘uint_fast8_t’ ‘UNSIGNED’ ‘C_UINT_FAST16_T’ ‘uint_fast16_t’ ‘UNSIGNED’ ‘C_UINT_FAST32_T’ ‘uint_fast32_t’ ‘UNSIGNED’ ‘C_UINT_FAST64_T’ ‘uint_fast64_t’ ‘UNSIGNED’ ‘C_UINT_FAST128_T’ ‘uint_fast128_t’ ‘UNSIGNED’ ‘C_UINT_LEAST8_T’ ‘uint_least8_t’ ‘UNSIGNED’ ‘C_UINT_LEAST16_T’ ‘uint_least16_t’ ‘UNSIGNED’ ‘C_UINT_LEAST32_T’ ‘uint_least32_t’ ‘UNSIGNED’ ‘C_UINT_LEAST64_T’ ‘uint_least64_t’ ‘UNSIGNED’ ‘C_UINT_LEAST128_T’ ‘uint_least128_t’ Additionally, the following parameters of type ‘CHARACTER(KIND=C_CHAR)’ are defined. Name C definition Value ------------------------------------------------------------ ‘C_NULL_CHAR’ null character ‘'\0'’ ‘C_ALERT’ alert ‘'\a'’ ‘C_BACKSPACE’ backspace ‘'\b'’ ‘C_FORM_FEED’ form feed ‘'\f'’ ‘C_NEW_LINE’ new line ‘'\n'’ ‘C_CARRIAGE_RETURN’carriage return ‘'\r'’ ‘C_HORIZONTAL_TAB’horizontal tab ‘'\t'’ ‘C_VERTICAL_TAB’vertical tab ‘'\v'’ Moreover, the following two named constants are defined: Name Type -------------------------------------------------------------------------- ‘C_NULL_PTR’ ‘C_PTR’ ‘C_NULL_FUNPTR’‘C_FUNPTR’ Both are equivalent to the value ‘NULL’ in C.  File: gfortran.info, Node: IEEE modules, Next: OpenMP Modules OMP_LIB and OMP_LIB_KINDS, Prev: ISO_C_BINDING, Up: Intrinsic Modules 9.3 IEEE modules: ‘IEEE_EXCEPTIONS’, ‘IEEE_ARITHMETIC’, and ‘IEEE_FEATURES’ =========================================================================== _Standard_: Fortran 2003 and later The ‘IEEE_EXCEPTIONS’, ‘IEEE_ARITHMETIC’, and ‘IEEE_FEATURES’ intrinsic modules provide support for exceptions and IEEE arithmetic, as defined in Fortran 2003 and later standards, and the IEC 60559:1989 standard (_Binary floating-point arithmetic for microprocessor systems_). These modules are only provided on the following supported platforms: • i386 and x86_64 processors • platforms that use the GNU C Library (glibc) • platforms with support for SysV/386 routines for floating-point interface (including Solaris and BSDs) • platforms with the AIX OS For full compliance with the Fortran standards, code using the ‘IEEE_EXCEPTIONS’ or ‘IEEE_ARITHMETIC’ modules should be compiled with the following options: ‘-fno-unsafe-math-optimizations -frounding-math -fsignaling-nans’.  File: gfortran.info, Node: OpenMP Modules OMP_LIB and OMP_LIB_KINDS, Next: OpenACC Module OPENACC, Prev: IEEE modules, Up: Intrinsic Modules 9.4 OpenMP Modules ‘OMP_LIB’ and ‘OMP_LIB_KINDS’ ================================================ _Standard_: OpenMP Application Program Interface v4.5, OpenMP Application Program Interface v5.0 (partially supported), OpenMP Application Program Interface v5.1 (partially supported) and OpenMP Application Program Interface v5.2 (partially supported). The OpenMP Fortran runtime library routines are provided both in a form of two Fortran modules, named ‘OMP_LIB’ and ‘OMP_LIB_KINDS’, and in a form of a Fortran ‘include’ file named ‘omp_lib.h’. The procedures provided by ‘OMP_LIB’ can be found in the *note Introduction: (libgomp)Top. manual, the named constants defined in the modules are listed below. For details refer to the actual OpenMP Application Program Interface v4.5 (https://www.openmp.org/wp-content/uploads/openmp-4.5.pdf), OpenMP Application Program Interface v5.0 (https://www.openmp.org/wp-content/uploads/OpenMP-API-Specification-5.0.pdf), OpenMP Application Program Interface v5.1 (https://www.openmp.org/wp-content/uploads/OpenMP-API-Specification-5-1.pdf) and OpenMP Application Program Interface v5.2 (https://www.openmp.org/wp-content/uploads/OpenMP-API-Specification-5-2.pdf). ‘OMP_LIB_KINDS’ provides the following scalar default-integer named constants: ‘omp_allocator_handle_kind’ ‘omp_alloctrait_key_kind’ ‘omp_alloctrait_val_kind’ ‘omp_depend_kind’ ‘omp_lock_kind’ ‘omp_lock_hint_kind’ ‘omp_nest_lock_kind’ ‘omp_pause_resource_kind’ ‘omp_memspace_handle_kind’ ‘omp_proc_bind_kind’ ‘omp_sched_kind’ ‘omp_sync_hint_kind’ ‘OMP_LIB’ provides the scalar default-integer named constant ‘openmp_version’ with a value of the form YYYYMM, where ‘yyyy’ is the year and MM the month of the OpenMP version; for OpenMP v4.5 the value is ‘201511’. The following derived type: ‘omp_alloctrait’ The following scalar default-integer named constants: ‘omp_initial_device’ ‘omp_invalid_device’ The following scalar integer named constants of the kind ‘omp_sched_kind’: ‘omp_sched_static’ ‘omp_sched_dynamic’ ‘omp_sched_guided’ ‘omp_sched_auto’ And the following scalar integer named constants of the kind ‘omp_proc_bind_kind’: ‘omp_proc_bind_false’ ‘omp_proc_bind_true’ ‘omp_proc_bind_primary’ ‘omp_proc_bind_master’ ‘omp_proc_bind_close’ ‘omp_proc_bind_spread’ The following scalar integer named constants are of the kind ‘omp_lock_hint_kind’: ‘omp_lock_hint_none’ ‘omp_lock_hint_uncontended’ ‘omp_lock_hint_contended’ ‘omp_lock_hint_nonspeculative’ ‘omp_lock_hint_speculative’ ‘omp_sync_hint_none’ ‘omp_sync_hint_uncontended’ ‘omp_sync_hint_contended’ ‘omp_sync_hint_nonspeculative’ ‘omp_sync_hint_speculative’ And the following two scalar integer named constants are of the kind ‘omp_pause_resource_kind’: ‘omp_pause_soft’ ‘omp_pause_hard’ The following scalar integer named constants are of the kind ‘omp_alloctrait_key_kind’: ‘omp_atk_sync_hint’ ‘omp_atk_alignment’ ‘omp_atk_access’ ‘omp_atk_pool_size’ ‘omp_atk_fallback’ ‘omp_atk_fb_data’ ‘omp_atk_pinned’ ‘omp_atk_partition’ The following scalar integer named constants are of the kind ‘omp_alloctrait_val_kind’: ‘omp_alloctrait_key_kind’: ‘omp_atv_default’ ‘omp_atv_false’ ‘omp_atv_true’ ‘omp_atv_contended’ ‘omp_atv_uncontended’ ‘omp_atv_serialized’ ‘omp_atv_sequential’ ‘omp_atv_private’ ‘omp_atv_all’ ‘omp_atv_thread’ ‘omp_atv_pteam’ ‘omp_atv_cgroup’ ‘omp_atv_default_mem_fb’ ‘omp_atv_null_fb’ ‘omp_atv_abort_fb’ ‘omp_atv_allocator_fb’ ‘omp_atv_environment’ ‘omp_atv_nearest’ ‘omp_atv_blocked’ The following scalar integer named constants are of the kind ‘omp_allocator_handle_kind’: ‘omp_null_allocator’ ‘omp_default_mem_alloc’ ‘omp_large_cap_mem_alloc’ ‘omp_const_mem_alloc’ ‘omp_high_bw_mem_alloc’ ‘omp_low_lat_mem_alloc’ ‘omp_cgroup_mem_alloc’ ‘omp_pteam_mem_alloc’ ‘omp_thread_mem_alloc’ The following scalar integer named constants are of the kind ‘omp_memspace_handle_kind’: ‘omp_default_mem_space’ ‘omp_large_cap_mem_space’ ‘omp_const_mem_space’ ‘omp_high_bw_mem_space’ ‘omp_low_lat_mem_space’  File: gfortran.info, Node: OpenACC Module OPENACC, Prev: OpenMP Modules OMP_LIB and OMP_LIB_KINDS, Up: Intrinsic Modules 9.5 OpenACC Module ‘OPENACC’ ============================ _Standard_: OpenACC Application Programming Interface v2.6 The OpenACC Fortran runtime library routines are provided both in a form of a Fortran 90 module, named ‘OPENACC’, and in form of a Fortran ‘include’ file named ‘openacc_lib.h’. The procedures provided by ‘OPENACC’ can be found in the *note Introduction: (libgomp)Top. manual, the named constants defined in the modules are listed below. For details refer to the actual OpenACC Application Programming Interface v2.6 (https://www.openacc.org/). ‘OPENACC’ provides the scalar default-integer named constant ‘openacc_version’ with a value of the form YYYYMM, where ‘yyyy’ is the year and MM the month of the OpenACC version; for OpenACC v2.6 the value is ‘201711’.  File: gfortran.info, Node: Contributing, Next: Copying, Prev: Intrinsic Modules, Up: Top Contributing ************ Free software is only possible if people contribute to efforts to create it. We're always in need of more people helping out with ideas and comments, writing documentation and contributing code. If you want to contribute to GNU Fortran, have a look at the long lists of projects you can take on. Some of these projects are small, some of them are large; some are completely orthogonal to the rest of what is happening on GNU Fortran, but others are "mainstream" projects in need of enthusiastic hackers. All of these projects are important! We will eventually get around to the things here, but they are also things doable by someone who is willing and able. * Menu: * Contributors:: * Projects::  File: gfortran.info, Node: Contributors, Next: Projects, Up: Contributing Contributors to GNU Fortran =========================== Most of the parser was hand-crafted by _Andy Vaught_, who is also the initiator of the whole project. Thanks Andy! Most of the interface with GCC was written by _Paul Brook_. The following individuals have contributed code and/or ideas and significant help to the GNU Fortran project (in alphabetical order): − Janne Blomqvist − Steven Bosscher − Paul Brook − Tobias Burnus − François-Xavier Coudert − Bud Davis − Jerry DeLisle − Erik Edelmann − Bernhard Fischer − Daniel Franke − Richard Guenther − Richard Henderson − Katherine Holcomb − Jakub Jelinek − Niels Kristian Bech Jensen − Steven Johnson − Steven G. Kargl − Thomas Koenig − Asher Langton − H. J. Lu − Toon Moene − Brooks Moses − Andrew Pinski − Tim Prince − Christopher D. Rickett − Richard Sandiford − Tobias Schlüter − Roger Sayle − Paul Thomas − Andy Vaught − Feng Wang − Janus Weil − Daniel Kraft The following people have contributed bug reports, smaller or larger patches, and much needed feedback and encouragement for the GNU Fortran project: − Bill Clodius − Dominique d'Humières − Kate Hedstrom − Erik Schnetter − Gerhard Steinmetz − Joost VandeVondele Many other individuals have helped debug, test and improve the GNU Fortran compiler over the past few years, and we welcome you to do the same! If you already have done so, and you would like to see your name listed in the list above, please contact us.  File: gfortran.info, Node: Projects, Prev: Contributors, Up: Contributing Projects ======== _Help build the test suite_ Solicit more code for donation to the test suite: the more extensive the testsuite, the smaller the risk of breaking things in the future! We can keep code private on request. _Bug hunting/squishing_ Find bugs and write more test cases! Test cases are especially very welcome, because it allows us to concentrate on fixing bugs instead of isolating them. Going through the bugzilla database at to reduce testcases posted there and add more information (for example, for which version does the testcase work, for which versions does it fail?) is also very helpful. _Missing features_ For a larger project, consider working on the missing features required for Fortran language standards compliance (*note Standards::), or contributing to the implementation of extensions such as OpenMP (*note OpenMP::) or OpenACC (*note OpenACC::) that are under active development. Again, contributing test cases for these features is useful too!  File: gfortran.info, Node: Copying, Next: GNU Free Documentation License, Prev: Contributing, Up: Top GNU General Public License ************************** Version 3, 29 June 2007 Copyright © 2007 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble ======== The GNU General Public License is a free, copyleft license for software and other kinds of works. The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program-to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too. 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You may convey covered works to others for the sole purpose of having them make modifications exclusively for you, or provide you with facilities for running those works, provided that you comply with the terms of this License in conveying all material for which you do not control copyright. Those thus making or running the covered works for you must do so exclusively on your behalf, under your direction and control, on terms that prohibit them from making any copies of your copyrighted material outside their relationship with you. Conveying under any other circumstances is permitted solely under the conditions stated below. Sublicensing is not allowed; section 10 makes it unnecessary. 3. Protecting Users' Legal Rights From Anti-Circumvention Law. No covered work shall be deemed part of an effective technological measure under any applicable law fulfilling obligations under article 11 of the WIPO copyright treaty adopted on 20 December 1996, or similar laws prohibiting or restricting circumvention of such measures. When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work's users, your or third parties' legal rights to forbid circumvention of technological measures. 4. Conveying Verbatim Copies. You may convey verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program. You may charge any price or no price for each copy that you convey, and you may offer support or warranty protection for a fee. 5. Conveying Modified Source Versions. You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions: a. The work must carry prominent notices stating that you modified it, and giving a relevant date. b. The work must carry prominent notices stating that it is released under this License and any conditions added under section 7. This requirement modifies the requirement in section 4 to "keep intact all notices". c. You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it. d. If the work has interactive user interfaces, each must display Appropriate Legal Notices; however, if the Program has interactive interfaces that do not display Appropriate Legal Notices, your work need not make them do so. A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an "aggregate" if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation's users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate. 6. Conveying Non-Source Forms. You may convey a covered work in object code form under the terms of sections 4 and 5, provided that you also convey the machine-readable Corresponding Source under the terms of this License, in one of these ways: a. Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by the Corresponding Source fixed on a durable physical medium customarily used for software interchange. b. Convey the object code in, or embodied in, a physical product (including a physical distribution medium), accompanied by a written offer, valid for at least three years and valid for as long as you offer spare parts or customer support for that product model, to give anyone who possesses the object code either (1) a copy of the Corresponding Source for all the software in the product that is covered by this License, on a durable physical medium customarily used for software interchange, for a price no more than your reasonable cost of physically performing this conveying of source, or (2) access to copy the Corresponding Source from a network server at no charge. c. Convey individual copies of the object code with a copy of the written offer to provide the Corresponding Source. This alternative is allowed only occasionally and noncommercially, and only if you received the object code with such an offer, in accord with subsection 6b. d. Convey the object code by offering access from a designated place (gratis or for a charge), and offer equivalent access to the Corresponding Source in the same way through the same place at no further charge. You need not require recipients to copy the Corresponding Source along with the object code. If the place to copy the object code is a network server, the Corresponding Source may be on a different server (operated by you or a third party) that supports equivalent copying facilities, provided you maintain clear directions next to the object code saying where to find the Corresponding Source. Regardless of what server hosts the Corresponding Source, you remain obligated to ensure that it is available for as long as needed to satisfy these requirements. e. Convey the object code using peer-to-peer transmission, provided you inform other peers where the object code and Corresponding Source of the work are being offered to the general public at no charge under subsection 6d. A separable portion of the object code, whose source code is excluded from the Corresponding Source as a System Library, need not be included in conveying the object code work. A "User Product" is either (1) a "consumer product", which means any tangible personal property which is normally used for personal, family, or household purposes, or (2) anything designed or sold for incorporation into a dwelling. In determining whether a product is a consumer product, doubtful cases shall be resolved in favor of coverage. 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If you convey an object code work under this section in, or with, or specifically for use in, a User Product, and the conveying occurs as part of a transaction in which the right of possession and use of the User Product is transferred to the recipient in perpetuity or for a fixed term (regardless of how the transaction is characterized), the Corresponding Source conveyed under this section must be accompanied by the Installation Information. But this requirement does not apply if neither you nor any third party retains the ability to install modified object code on the User Product (for example, the work has been installed in ROM). The requirement to provide Installation Information does not include a requirement to continue to provide support service, warranty, or updates for a work that has been modified or installed by the recipient, or for the User Product in which it has been modified or installed. Access to a network may be denied when the modification itself materially and adversely affects the operation of the network or violates the rules and protocols for communication across the network. Corresponding Source conveyed, and Installation Information provided, in accord with this section must be in a format that is publicly documented (and with an implementation available to the public in source code form), and must require no special password or key for unpacking, reading or copying. 7. Additional Terms. "Additional permissions" are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions. When you convey a copy of a covered work, you may at your option remove any additional permissions from that copy, or from any part of it. (Additional permissions may be written to require their own removal in certain cases when you modify the work.) You may place additional permissions on material, added by you to a covered work, for which you have or can give appropriate copyright permission. Notwithstanding any other provision of this License, for material you add to a covered work, you may (if authorized by the copyright holders of that material) supplement the terms of this License with terms: a. Disclaiming warranty or limiting liability differently from the terms of sections 15 and 16 of this License; or b. Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it; or c. Prohibiting misrepresentation of the origin of that material, or requiring that modified versions of such material be marked in reasonable ways as different from the original version; or d. Limiting the use for publicity purposes of names of licensors or authors of the material; or e. Declining to grant rights under trademark law for use of some trade names, trademarks, or service marks; or f. Requiring indemnification of licensors and authors of that material by anyone who conveys the material (or modified versions of it) with contractual assumptions of liability to the recipient, for any liability that these contractual assumptions directly impose on those licensors and authors. All other non-permissive additional terms are considered "further restrictions" within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying. If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms. Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way. 8. Termination. You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11). However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation. Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice. Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10. 9. Acceptance Not Required for Having Copies. You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so. 10. Automatic Licensing of Downstream Recipients. Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License. An "entity transaction" is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party's predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts. You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it. 11. Patents. A "contributor" is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor's "contributor version". A contributor's "essential patent claims" are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, "control" includes the right to grant patent sublicenses in a manner consistent with the requirements of this License. Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor's essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version. In the following three paragraphs, a "patent license" is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To "grant" such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party. If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. "Knowingly relying" means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient's use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid. If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it. A patent license is "discriminatory" if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007. Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law. 12. No Surrender of Others' Freedom. If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program. 13. Use with the GNU Affero General Public License. Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such. 14. Revised Versions of this License. The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License "or any later version" applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation. If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Program. Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version. 15. Disclaimer of Warranty. THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 16. Limitation of Liability. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 17. Interpretation of Sections 15 and 16. If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee. END OF TERMS AND CONDITIONS =========================== How to Apply These Terms to Your New Programs ============================================= If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. Copyright (C) YEAR NAME OF AUTHOR This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . Also add information on how to contact you by electronic and paper mail. If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode: PROGRAM Copyright (C) YEAR NAME OF AUTHOR This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’. This is free software, and you are welcome to redistribute it under certain conditions; type ‘show c’ for details. The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an "about box". You should also get your employer (if you work as a programmer) or school, if any, to sign a "copyright disclaimer" for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see . The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read .  File: gfortran.info, Node: GNU Free Documentation License, Next: Funding, Prev: Copying, Up: Top GNU Free Documentation License ****************************** Version 1.3, 3 November 2008 Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. PREAMBLE The purpose of this License is to make a manual, textbook, or other functional and useful document “free” in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software. We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference. 1. APPLICABILITY AND DEFINITIONS This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law. A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language. A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them. The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none. The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words. A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not "Transparent" is called "Opaque". Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only. The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text. The "publisher" means any person or entity that distributes copies of the Document to the public. A section "Entitled XYZ" means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as "Acknowledgements", "Dedications", "Endorsements", or "History".) To "Preserve the Title" of such a section when you modify the Document means that it remains a section "Entitled XYZ" according to this definition. The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License. 2. VERBATIM COPYING You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3. You may also lend copies, under the same conditions stated above, and you may publicly display copies. 3. COPYING IN QUANTITY If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects. If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages. If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. 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Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence. J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission. K. For any section Entitled "Acknowledgements" or "Dedications", Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein. L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles. M. Delete any section Entitled "Endorsements". Such a section may not be included in the Modified Version. N. Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title with any Invariant Section. O. Preserve any Warranty Disclaimers. If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. 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TRANSLATION Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail. If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title. 9. 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Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it. 10. FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See . Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Document. 11. RELICENSING "Massive Multiauthor Collaboration Site" (or "MMC Site") means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A "Massive Multiauthor Collaboration" (or "MMC") contained in the site means any set of copyrightable works thus published on the MMC site. "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization. "Incorporate" means to publish or republish a Document, in whole or in part, as part of another Document. An MMC is "eligible for relicensing" if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008. The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing. ADDENDUM: How to use this License for your documents ==================================================== To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page: Copyright (C) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this: with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.  File: gfortran.info, Node: Funding, Next: Option Index, Prev: GNU Free Documentation License, Up: Top Funding Free Software ********************* If you want to have more free software a few years from now, it makes sense for you to help encourage people to contribute funds for its development. The most effective approach known is to encourage commercial redistributors to donate. Users of free software systems can boost the pace of development by encouraging for-a-fee distributors to donate part of their selling price to free software developers--the Free Software Foundation, and others. The way to convince distributors to do this is to demand it and expect it from them. So when you compare distributors, judge them partly by how much they give to free software development. Show distributors they must compete to be the one who gives the most. To make this approach work, you must insist on numbers that you can compare, such as, "We will donate ten dollars to the Frobnitz project for each disk sold." Don't be satisfied with a vague promise, such as "A portion of the profits are donated," since it doesn't give a basis for comparison. Even a precise fraction "of the profits from this disk" is not very meaningful, since creative accounting and unrelated business decisions can greatly alter what fraction of the sales price counts as profit. If the price you pay is $50, ten percent of the profit is probably less than a dollar; it might be a few cents, or nothing at all. Some redistributors do development work themselves. This is useful too; but to keep everyone honest, you need to inquire how much they do, and what kind. Some kinds of development make much more long-term difference than others. For example, maintaining a separate version of a program contributes very little; maintaining the standard version of a program for the whole community contributes much. Easy new ports contribute little, since someone else would surely do them; difficult ports such as adding a new CPU to the GNU Compiler Collection contribute more; major new features or packages contribute the most. By establishing the idea that supporting further development is "the proper thing to do" when distributing free software for a fee, we can assure a steady flow of resources into making more free software. Copyright © 1994 Free Software Foundation, Inc. Verbatim copying and redistribution of this section is permitted without royalty; alteration is not permitted.  File: gfortran.info, Node: Option Index, Next: Keyword Index, Prev: Funding, Up: Top Option Index ************ ‘gfortran’'s command line options are indexed here without any initial ‘-’ or ‘--’. Where an option has both positive and negative forms (such as -foption and -fno-option), relevant entries in the manual are indexed under the most appropriate form; it may sometimes be useful to look up both forms. [index] * Menu: * A-PREDICATE=ANSWER: Preprocessing Options. (line 149) * allow-invalid-boz: Fortran Dialect Options. (line 38) * APREDICATE=ANSWER: Preprocessing Options. (line 143) * backslash: Fortran Dialect Options. (line 113) * C: Preprocessing Options. (line 152) * c-prototypes: Interoperability Options. (line 6) * c-prototypes-external: Interoperability Options. (line 24) * CC: Preprocessing Options. (line 167) * cpp: Preprocessing Options. (line 41) * dD: Preprocessing Options. (line 65) * dI: Preprocessing Options. (line 81) * dM: Preprocessing Options. (line 56) * dN: Preprocessing Options. (line 71) * DNAME: Preprocessing Options. (line 181) * DNAME=DEFINITION: Preprocessing Options. (line 184) * dU: Preprocessing Options. (line 74) * faggressive-function-elimination: Code Gen Options. (line 462) * falign-commons: Code Gen Options. (line 435) * fall-intrinsics: Fortran Dialect Options. (line 16) * fallow-argument-mismatch: Fortran Dialect Options. (line 25) * fblas-matmul-limit: Code Gen Options. (line 336) * fbounds-check: Code Gen Options. (line 204) * fcheck: Code Gen Options. (line 143) * fcheck-array-temporaries: Code Gen Options. (line 238) * fcoarray: Code Gen Options. (line 127) * fconvert=CONVERSION: Runtime Options. (line 9) * fcray-pointer: Fortran Dialect Options. (line 168) * fd-lines-as-code: Fortran Dialect Options. (line 44) * fd-lines-as-comments: Fortran Dialect Options. (line 44) * fdebug-aux-vars: Debugging Options. (line 9) * fdec: Fortran Dialect Options. (line 52) * fdec-blank-format-item: Fortran Dialect Options. (line 103) * fdec-char-conversions: Fortran Dialect Options. (line 67) * fdec-format-defaults: Fortran Dialect Options. (line 99) * fdec-include: Fortran Dialect Options. (line 93) * fdec-intrinsic-ints: Fortran Dialect Options. (line 77) * fdec-math: Fortran Dialect Options. (line 82) * fdec-static: Fortran Dialect Options. (line 89) * fdec-structure: Fortran Dialect Options. (line 71) * fdefault-double-8: Fortran Dialect Options. (line 269) * fdefault-integer-8: Fortran Dialect Options. (line 233) * fdefault-real-10: Fortran Dialect Options. (line 249) * fdefault-real-16: Fortran Dialect Options. (line 259) * fdefault-real-8: Fortran Dialect Options. (line 239) * fdollar-ok: Fortran Dialect Options. (line 107) * fdump-fortran-global: Developer Options. (line 9) * fdump-fortran-optimized: Developer Options. (line 16) * fdump-fortran-original: Developer Options. (line 23) * fdump-parse-tree: Developer Options. (line 31) * fexternal-blas: Code Gen Options. (line 328) * ff2c: Code Gen Options. (line 27) * ffixed-form: Fortran Dialect Options. (line 9) * ffixed-line-length-N: Fortran Dialect Options. (line 130) * ffpe-summary=LIST: Debugging Options. (line 51) * ffpe-trap=LIST: Debugging Options. (line 17) * ffree-form: Fortran Dialect Options. (line 9) * ffree-line-length-N: Fortran Dialect Options. (line 152) * fimplicit-none: Fortran Dialect Options. (line 163) * finit-character: Code Gen Options. (line 394) * finit-derived: Code Gen Options. (line 394) * finit-integer: Code Gen Options. (line 394) * finit-local-zero: Code Gen Options. (line 394) * finit-logical: Code Gen Options. (line 394) * finit-real: Code Gen Options. (line 394) * finline-arg-packing: Code Gen Options. (line 303) * finline-intrinsics: Code Gen Options. (line 346) * finline-matmul-limit: Code Gen Options. (line 375) * finteger-4-integer-8: Fortran Dialect Options. (line 277) * fintrinsic-modules-path: Directory Options. (line 35) * fmax-array-constructor: Code Gen Options. (line 241) * fmax-errors=N: Error and Warning Options. (line 26) * fmax-identifier-length=N: Fortran Dialect Options. (line 159) * fmax-stack-var-size: Code Gen Options. (line 259) * fmax-subrecord-length=LENGTH: Runtime Options. (line 36) * fmodule-private: Fortran Dialect Options. (line 125) * fno-automatic: Code Gen Options. (line 14) * fno-backtrace: Debugging Options. (line 64) * fno-protect-parens: Code Gen Options. (line 447) * fno-underscoring: Code Gen Options. (line 56) * fopenacc: Fortran Dialect Options. (line 172) * fopenmp: Fortran Dialect Options. (line 181) * fopenmp-allocators: Fortran Dialect Options. (line 192) * fopenmp-simd: Fortran Dialect Options. (line 210) * fpack-derived: Code Gen Options. (line 281) * fpad-source: Fortran Dialect Options. (line 144) * fpp: Preprocessing Options. (line 41) * frange-check: Fortran Dialect Options. (line 221) * freal-4-real-10: Fortran Dialect Options. (line 287) * freal-4-real-16: Fortran Dialect Options. (line 287) * freal-4-real-8: Fortran Dialect Options. (line 287) * freal-8-real-10: Fortran Dialect Options. (line 287) * freal-8-real-16: Fortran Dialect Options. (line 287) * freal-8-real-4: Fortran Dialect Options. (line 287) * frealloc-lhs: Code Gen Options. (line 456) * frecord-marker=LENGTH: Runtime Options. (line 28) * frecursive: Code Gen Options. (line 389) * frepack-arrays: Code Gen Options. (line 287) * frontend-loop-interchange: Code Gen Options. (line 483) * frontend-optimize: Code Gen Options. (line 470) * fsecond-underscore: Code Gen Options. (line 113) * fshort-enums: Code Gen Options. (line 297) * fsign-zero: Runtime Options. (line 41) * fstack-arrays: Code Gen Options. (line 273) * fsyntax-only: Error and Warning Options. (line 32) * ftest-forall-temp: Fortran Dialect Options. (line 338) * funsigned: Fortran Dialect Options. (line 342) * fworking-directory: Preprocessing Options. (line 85) * H: Preprocessing Options. (line 204) * IDIR: Directory Options. (line 13) * idirafter: Preprocessing Options. (line 99) * imultilib: Preprocessing Options. (line 106) * iprefix: Preprocessing Options. (line 110) * iquote: Preprocessing Options. (line 119) * isysroot: Preprocessing Options. (line 115) * isystem: Preprocessing Options. (line 126) * JDIR: Directory Options. (line 28) * nostdinc: Preprocessing Options. (line 134) * P: Preprocessing Options. (line 209) * pedantic: Error and Warning Options. (line 37) * pedantic-errors: Error and Warning Options. (line 57) * static-libgfortran: Link Options. (line 10) * static-libquadmath: Link Options. (line 16) * std=STD: Fortran Dialect Options. (line 315) * tail-call-workaround: Code Gen Options. (line 207) * UNAME: Preprocessing Options. (line 215) * undef: Preprocessing Options. (line 139) * Waliasing: Error and Warning Options. (line 70) * Walign-commons: Error and Warning Options. (line 240) * Wall: Error and Warning Options. (line 61) * Wampersand: Error and Warning Options. (line 87) * Warray-temporaries: Error and Warning Options. (line 96) * Wc-binding-type: Error and Warning Options. (line 101) * Wcharacter-truncation: Error and Warning Options. (line 108) * Wcompare-reals: Error and Warning Options. (line 268) * Wconversion: Error and Warning Options. (line 117) * Wconversion-extra: Error and Warning Options. (line 121) * Wdo-subscript: Error and Warning Options. (line 280) * Werror: Error and Warning Options. (line 292) * Wexternal-argument-mismatch: Error and Warning Options. (line 125) * Wextra: Error and Warning Options. (line 131) * Wfrontend-loop-interchange: Error and Warning Options. (line 136) * Wfunction-elimination: Error and Warning Options. (line 246) * Wimplicit-interface: Error and Warning Options. (line 140) * Wimplicit-procedure: Error and Warning Options. (line 146) * Winteger-division: Error and Warning Options. (line 150) * Wintrinsic-shadow: Error and Warning Options. (line 218) * Wintrinsics-std: Error and Warning Options. (line 154) * Wline-truncation: Error and Warning Options. (line 111) * Woverwrite-recursive: Error and Warning Options. (line 161) * Wpedantic: Error and Warning Options. (line 37) * Wreal-q-constant: Error and Warning Options. (line 168) * Wrealloc-lhs: Error and Warning Options. (line 251) * Wrealloc-lhs-all: Error and Warning Options. (line 263) * Wsurprising: Error and Warning Options. (line 172) * Wtabs: Error and Warning Options. (line 201) * Wtargt-lifetime: Error and Warning Options. (line 272) * Wundefined-do-loop: Error and Warning Options. (line 209) * Wunderflow: Error and Warning Options. (line 214) * Wunused-dummy-argument: Error and Warning Options. (line 229) * Wunused-parameter: Error and Warning Options. (line 233) * Wuse-without-only: Error and Warning Options. (line 225) * Wzerotrip: Error and Warning Options. (line 276)  File: gfortran.info, Node: Keyword Index, Prev: Option Index, Up: Top Keyword Index ************* [index] * Menu: * _gfortran_set_args: _gfortran_set_args. (line 6) * _gfortran_set_convert: _gfortran_set_convert. (line 6) * _gfortran_set_fpe: _gfortran_set_fpe. (line 6) * _gfortran_set_max_subrecord_length: _gfortran_set_max_subrecord_length. (line 6) * _gfortran_set_options: _gfortran_set_options. (line 6) * _gfortran_set_record_marker: _gfortran_set_record_marker. (line 6) * , conversion, to unsigned: UINT. (line 6) * &: Error and Warning Options. (line 87) * %LOC: Argument list functions. (line 6) * %REF: Argument list functions. (line 6) * %VAL: Argument list functions. (line 6) * $: Fortran Dialect Options. (line 107) * ABORT: ABORT. (line 6) * ABS: ABS. (line 6) * absolute value: ABS. (line 6) * ACCESS: ACCESS. (line 6) * ACHAR: ACHAR. (line 6) * ACOS: ACOS. (line 6) * ACOSD: ACOSD. (line 6) * ACOSH: ACOSH. (line 6) * adjust string: ADJUSTL. (line 6) * adjust string <1>: ADJUSTR. (line 6) * ADJUSTL: ADJUSTL. (line 6) * ADJUSTR: ADJUSTR. (line 6) * AIMAG: AIMAG. (line 6) * AINT: AINT. (line 6) * ALARM: ALARM. (line 6) * ALGAMA: LOG_GAMMA. (line 6) * aliasing: Error and Warning Options. (line 70) * alignment of COMMON blocks: Error and Warning Options. (line 240) * alignment of COMMON blocks <1>: Code Gen Options. (line 435) * ALL: ALL. (line 6) * all warnings: Error and Warning Options. (line 61) * ALLOCATED: ALLOCATED. (line 6) * allocation, moving: MOVE_ALLOC. (line 6) * allocation, status: ALLOCATED. (line 6) * ALOG: LOG. (line 6) * ALOG10: LOG10. (line 6) * AMAX0: MAX. (line 6) * AMAX1: MAX. (line 6) * AMIN0: MIN. (line 6) * AMIN1: MIN. (line 6) * AMOD: MOD. (line 6) * AND: AND. (line 6) * ANINT: ANINT. (line 6) * ANY: ANY. (line 6) * area hyperbolic cosine: ACOSH. (line 6) * area hyperbolic sine: ASINH. (line 6) * area hyperbolic tangent: ATANH. (line 6) * argment mismatch, warnings: Error and Warning Options. (line 125) * argument list functions: Argument list functions. (line 6) * argument mismatch: Fortran Dialect Options. (line 25) * Argument passing conventions: Argument passing conventions. (line 6) * arguments, to program: COMMAND_ARGUMENT_COUNT. (line 6) * arguments, to program <1>: GETARG. (line 6) * arguments, to program <2>: GET_COMMAND. (line 6) * arguments, to program <3>: GET_COMMAND_ARGUMENT. (line 6) * arguments, to program <4>: IARGC. (line 6) * array descriptor: Further Interoperability of Fortran with C. (line 6) * array, add elements: SUM. (line 6) * array, AND: IALL. (line 6) * array, apply condition: ALL. (line 6) * array, apply condition <1>: ANY. (line 6) * array, bounds checking: Code Gen Options. (line 143) * array, change dimensions: RESHAPE. (line 6) * array, combine arrays: MERGE. (line 6) * array, condition testing: ALL. (line 6) * array, condition testing <1>: ANY. (line 6) * array, conditionally add elements: SUM. (line 6) * array, conditionally count elements: COUNT. (line 6) * array, conditionally multiply elements: PRODUCT. (line 6) * array, contiguity: IS_CONTIGUOUS. (line 6) * array, count elements: SIZE. (line 6) * array, duplicate dimensions: SPREAD. (line 6) * array, duplicate elements: SPREAD. (line 6) * array, element counting: COUNT. (line 6) * array, gather elements: PACK. (line 6) * array, increase dimension: SPREAD. (line 6) * array, increase dimension <1>: UNPACK. (line 6) * array, indices of type real: Real array indices. (line 6) * array, location of maximum element: MAXLOC. (line 6) * array, location of minimum element: MINLOC. (line 6) * array, lower bound: LBOUND. (line 6) * array, maximum value: MAXVAL. (line 6) * array, merge arrays: MERGE. (line 6) * array, minimum value: MINVAL. (line 6) * array, multiply elements: PRODUCT. (line 6) * array, number of elements: COUNT. (line 6) * array, number of elements <1>: SIZE. (line 6) * array, OR: IANY. (line 6) * array, packing: PACK. (line 6) * array, parity: IPARITY. (line 6) * array, permutation: CSHIFT. (line 6) * array, product: PRODUCT. (line 6) * array, reduce dimension: PACK. (line 6) * array, rotate: CSHIFT. (line 6) * array, scatter elements: UNPACK. (line 6) * array, shape: SHAPE. (line 6) * array, shift: EOSHIFT. (line 6) * array, shift circularly: CSHIFT. (line 6) * array, size: SIZE. (line 6) * array, sum: SUM. (line 6) * array, transmogrify: RESHAPE. (line 6) * array, transpose: TRANSPOSE. (line 6) * array, unpacking: UNPACK. (line 6) * array, upper bound: UBOUND. (line 6) * array, XOR: IPARITY. (line 6) * ASCII collating sequence: ACHAR. (line 6) * ASCII collating sequence <1>: IACHAR. (line 6) * ASIN: ASIN. (line 6) * ASIND: ASIND. (line 6) * ASINH: ASINH. (line 6) * ASSOCIATED: ASSOCIATED. (line 6) * association status: ASSOCIATED. (line 6) * association status, C pointer: C_ASSOCIATED. (line 6) * assumed-rank: Further Interoperability of Fortran with C. (line 6) * assumed-type: Further Interoperability of Fortran with C. (line 6) * asynchronous I/O: Asynchronous I/O. (line 6) * ATAN: ATAN. (line 6) * ATAN2: ATAN2. (line 6) * ATAN2D: ATAN2D. (line 6) * ATAND: ATAND. (line 6) * ATANH: ATANH. (line 6) * Atomic subroutine, add: ATOMIC_ADD. (line 6) * Atomic subroutine, ADD with fetch: ATOMIC_FETCH_ADD. (line 6) * Atomic subroutine, AND: ATOMIC_AND. (line 6) * Atomic subroutine, AND with fetch: ATOMIC_FETCH_AND. (line 6) * Atomic subroutine, compare and swap: ATOMIC_CAS. (line 6) * Atomic subroutine, define: ATOMIC_DEFINE. (line 6) * Atomic subroutine, OR: ATOMIC_OR. (line 6) * Atomic subroutine, OR with fetch: ATOMIC_FETCH_OR. (line 6) * Atomic subroutine, reference: ATOMIC_REF. (line 6) * Atomic subroutine, XOR: ATOMIC_XOR. (line 6) * Atomic subroutine, XOR with fetch: ATOMIC_FETCH_XOR. (line 6) * ATOMIC_ADD: ATOMIC_ADD. (line 6) * ATOMIC_AND: ATOMIC_AND. (line 6) * ATOMIC_DEFINE: ATOMIC_CAS. (line 6) * ATOMIC_DEFINE <1>: ATOMIC_DEFINE. (line 6) * ATOMIC_FETCH_ADD: ATOMIC_FETCH_ADD. (line 6) * ATOMIC_FETCH_AND: ATOMIC_FETCH_AND. (line 6) * ATOMIC_FETCH_OR: ATOMIC_FETCH_OR. (line 6) * ATOMIC_FETCH_XOR: ATOMIC_FETCH_XOR. (line 6) * ATOMIC_OR: ATOMIC_OR. (line 6) * ATOMIC_REF: ATOMIC_REF. (line 6) * ATOMIC_XOR: ATOMIC_XOR. (line 6) * ATTRIBUTES directive: ATTRIBUTES directive. (line 6) * Authors: Contributors. (line 6) * AUTOMATIC: AUTOMATIC and STATIC attributes. (line 6) * BABS: ABS. (line 6) * backslash: Fortran Dialect Options. (line 113) * BACKSPACE: Read/Write after EOF marker. (line 6) * BACKTRACE: BACKTRACE. (line 6) * backtrace: Debugging Options. (line 64) * backtrace <1>: BACKTRACE. (line 6) * base 10 logarithm function: LOG10. (line 6) * BBCLR: IBCLR. (line 6) * BBITS: IBITS. (line 6) * BBSET: IBSET. (line 6) * BBTEST: BTEST. (line 6) * BESJ0: BESSEL_J0. (line 6) * BESJ1: BESSEL_J1. (line 6) * BESJN: BESSEL_JN. (line 6) * Bessel function, first kind: BESSEL_J0. (line 6) * Bessel function, first kind <1>: BESSEL_J1. (line 6) * Bessel function, first kind <2>: BESSEL_JN. (line 6) * Bessel function, second kind: BESSEL_Y0. (line 6) * Bessel function, second kind <1>: BESSEL_Y1. (line 6) * Bessel function, second kind <2>: BESSEL_YN. (line 6) * BESSEL_J0: BESSEL_J0. (line 6) * BESSEL_J1: BESSEL_J1. (line 6) * BESSEL_JN: BESSEL_JN. (line 6) * BESSEL_Y0: BESSEL_Y0. (line 6) * BESSEL_Y1: BESSEL_Y1. (line 6) * BESSEL_YN: BESSEL_YN. (line 6) * BESY0: BESSEL_Y0. (line 6) * BESY1: BESSEL_Y1. (line 6) * BESYN: BESSEL_YN. (line 6) * BGE: BGE. (line 6) * BGT: BGT. (line 6) * BIAND: IAND. (line 6) * BIEOR: IEOR. (line 6) * binary representation: POPCNT. (line 6) * binary representation <1>: POPPAR. (line 6) * BIOR: IOR. (line 6) * bit intrinsics checking: Code Gen Options. (line 143) * BIT_SIZE: BIT_SIZE. (line 6) * BITEST: BTEST. (line 6) * bits set: POPCNT. (line 6) * bits, AND of array elements: IALL. (line 6) * bits, clear: IBCLR. (line 6) * bits, extract: IBITS. (line 6) * bits, get: IBITS. (line 6) * bits, merge: MERGE_BITS. (line 6) * bits, move: MVBITS. (line 6) * bits, move <1>: TRANSFER. (line 6) * bits, negate: NOT. (line 6) * bits, number of: BIT_SIZE. (line 6) * bits, OR of array elements: IANY. (line 6) * bits, set: IBSET. (line 6) * bits, shift: ISHFT. (line 6) * bits, shift circular: ISHFTC. (line 6) * bits, shift left: LSHIFT. (line 6) * bits, shift left <1>: SHIFTL. (line 6) * bits, shift right: RSHIFT. (line 6) * bits, shift right <1>: SHIFTA. (line 6) * bits, shift right <2>: SHIFTR. (line 6) * bits, testing: BTEST. (line 6) * bits, unset: IBCLR. (line 6) * bits, XOR of array elements: IPARITY. (line 6) * bitwise comparison: BGE. (line 6) * bitwise comparison <1>: BGT. (line 6) * bitwise comparison <2>: BLE. (line 6) * bitwise comparison <3>: BLT. (line 6) * bitwise logical and: AND. (line 6) * bitwise logical and <1>: IAND. (line 6) * bitwise logical exclusive or: IEOR. (line 6) * bitwise logical exclusive or <1>: XOR. (line 6) * bitwise logical not: NOT. (line 6) * bitwise logical or: IOR. (line 6) * bitwise logical or <1>: OR. (line 6) * BJTEST: BTEST. (line 6) * BKTEST: BTEST. (line 6) * BLE: BLE. (line 6) * BLT: BLT. (line 6) * BMOD: MOD. (line 6) * BMVBITS: MVBITS. (line 6) * BNOT: NOT. (line 6) * bounds checking: Code Gen Options. (line 143) * BOZ literal constants: BOZ literal constants. (line 6) * BSHFT: ISHFT. (line 6) * BSHFTC: ISHFTC. (line 6) * BTEST: BTEST. (line 6) * BUILTIN directive: BUILTIN directive. (line 6) * C derived type and struct interoperability: Derived Types and struct. (line 6) * C interoperability: Interoperability with C. (line 6) * C intrinsic type interoperability: Intrinsic Types. (line 6) * C pointers: Working with C Pointers. (line 6) * C procedure interoperability: Interoperable Subroutines and Functions. (line 6) * C prototypes: Generating C prototypes from Fortran. (line 6) * C variable interoperability: Interoperable Global Variables. (line 6) * C_ASSOCIATED: C_ASSOCIATED. (line 6) * C_F_POINTER: C_F_POINTER. (line 6) * C_F_PROCPOINTER: C_F_PROCPOINTER. (line 6) * C_FUNLOC: C_FUNLOC. (line 6) * C_LOC: C_LOC. (line 6) * C_SIZEOF: C_SIZEOF. (line 6) * CABS: ABS. (line 6) * caf_deregister_t: caf_deregister_t. (line 6) * caf_reference_t: caf_reference_t. (line 6) * caf_register_t: caf_register_t. (line 6) * caf_token_t: caf_token_t. (line 6) * calling convention: Code Gen Options. (line 27) * CARRIAGECONTROL: Extended I/O specifiers. (line 6) * CCOS: COS. (line 6) * CCOSD: COSD. (line 6) * CDABS: ABS. (line 6) * CDCOS: COS. (line 6) * CDCOSD: COSD. (line 6) * CDEXP: EXP. (line 6) * CDLOG: LOG. (line 6) * CDSIN: SIN. (line 6) * CDSIND: SIND. (line 6) * CDSQRT: SQRT. (line 6) * CEILING: CEILING. (line 6) * ceiling: ANINT. (line 6) * ceiling <1>: CEILING. (line 6) * CEXP: EXP. (line 6) * CHAR: CHAR. (line 6) * character kind: SELECTED_CHAR_KIND. (line 6) * character set: Fortran Dialect Options. (line 107) * CHDIR: CHDIR. (line 6) * checking array temporaries: Code Gen Options. (line 143) * checking subscripts: Code Gen Options. (line 143) * CHMOD: CHMOD. (line 6) * clock ticks: MCLOCK. (line 6) * clock ticks <1>: MCLOCK8. (line 6) * clock ticks <2>: SYSTEM_CLOCK. (line 6) * CLOG: LOG. (line 6) * CMPLX: CMPLX. (line 6) * CO_BROADCAST: CO_BROADCAST. (line 6) * CO_MAX: CO_MAX. (line 6) * CO_MIN: CO_MIN. (line 6) * CO_REDUCE: CO_REDUCE. (line 6) * CO_SUM: CO_SUM. (line 6) * Coarray Function ABI: Function ABI Documentation. (line 6) * Coarray type and enum ABI: Type and enum ABI Documentation. (line 6) * Coarray, _gfortran_caf_atomic_cas: _gfortran_caf_atomic_cas. (line 6) * Coarray, _gfortran_caf_atomic_define: _gfortran_caf_atomic_define. (line 6) * Coarray, _gfortran_caf_atomic_op: _gfortran_caf_atomic_op. (line 6) * Coarray, _gfortran_caf_atomic_ref: _gfortran_caf_atomic_ref. (line 6) * Coarray, _gfortran_caf_co_broadcast: _gfortran_caf_co_broadcast. (line 6) * Coarray, _gfortran_caf_co_max: _gfortran_caf_co_max. (line 6) * Coarray, _gfortran_caf_co_min: _gfortran_caf_co_min. (line 6) * Coarray, _gfortran_caf_co_reduce: _gfortran_caf_co_reduce. (line 6) * Coarray, _gfortran_caf_co_sum: _gfortran_caf_co_sum. (line 6) * Coarray, _gfortran_caf_deregister: _gfortran_caf_deregister. (line 6) * Coarray, _gfortran_caf_error_stop: _gfortran_caf_error_stop. (line 6) * Coarray, _gfortran_caf_error_stop_str: _gfortran_caf_error_stop_str. (line 6) * Coarray, _gfortran_caf_event_post: _gfortran_caf_event_post. (line 6) * Coarray, _gfortran_caf_event_query: _gfortran_caf_event_query. (line 6) * Coarray, _gfortran_caf_event_wait: _gfortran_caf_event_wait. (line 6) * Coarray, _gfortran_caf_fail_image: _gfortran_caf_fail_image. (line 6) * Coarray, _gfortran_caf_failed_images: _gfortran_caf_failed_images. (line 6) * Coarray, _gfortran_caf_finish: _gfortran_caf_finish. (line 6) * Coarray, _gfortran_caf_get_from_remote: _gfortran_caf_get_from_remote. (line 6) * Coarray, _gfortran_caf_get_remote_function_index: _gfortran_caf_get_remote_function_index. (line 6) * Coarray, _gfortran_caf_image_status: _gfortran_caf_image_status. (line 6) * Coarray, _gfortran_caf_init: _gfortran_caf_init. (line 6) * Coarray, _gfortran_caf_is_present_on_remote: _gfortran_caf_is_present_on_remote. (line 6) * Coarray, _gfortran_caf_lock: _gfortran_caf_lock. (line 6) * Coarray, _gfortran_caf_num_images: _gfortran_caf_num_images. (line 6) * Coarray, _gfortran_caf_register: _gfortran_caf_register. (line 6) * Coarray, _gfortran_caf_register_accessor: _gfortran_caf_register_accessor. (line 6) * Coarray, _gfortran_caf_register_accessors_finish: _gfortran_caf_register_accessors_finish. (line 6) * Coarray, _gfortran_caf_send_to_remote: _gfortran_caf_send_to_remote. (line 6) * Coarray, _gfortran_caf_sendget_by_ref: _gfortran_caf_sendget_by_ref. (line 6) * Coarray, _gfortran_caf_stopped_images: _gfortran_caf_stopped_images. (line 6) * Coarray, _gfortran_caf_sync_all: _gfortran_caf_sync_all. (line 6) * Coarray, _gfortran_caf_sync_images: _gfortran_caf_sync_images. (line 6) * Coarray, _gfortran_caf_sync_memory: _gfortran_caf_sync_memory. (line 6) * Coarray, _gfortran_caf_this_image: _gfortran_caf_this_image. (line 6) * Coarray, _gfortran_caf_transfer_between_remotes: _gfortran_caf_transfer_between_remotes. (line 6) * Coarray, _gfortran_caf_unlock: _gfortran_caf_unlock. (line 6) * coarray, IMAGE_INDEX: IMAGE_INDEX. (line 6) * coarray, lower bound: LCOBOUND. (line 6) * coarray, NUM_IMAGES: NUM_IMAGES. (line 6) * coarray, THIS_IMAGE: THIS_IMAGE. (line 6) * coarray, upper bound: UCOBOUND. (line 6) * coarrays: Code Gen Options. (line 127) * Coarrays: Coarray Programming. (line 6) * code generation, conventions: Code Gen Options. (line 6) * collating sequence, ASCII: ACHAR. (line 6) * collating sequence, ASCII <1>: IACHAR. (line 6) * Collectives, generic reduction: CO_REDUCE. (line 6) * Collectives, maximal value: CO_MAX. (line 6) * Collectives, minimal value: CO_MIN. (line 6) * Collectives, sum of values: CO_SUM. (line 6) * Collectives, value broadcasting: CO_BROADCAST. (line 6) * command line: EXECUTE_COMMAND_LINE. (line 6) * command options: Invoking GNU Fortran. (line 6) * COMMAND_ARGUMENT_COUNT: COMMAND_ARGUMENT_COUNT. (line 6) * command-line arguments: COMMAND_ARGUMENT_COUNT. (line 6) * command-line arguments <1>: GETARG. (line 6) * command-line arguments <2>: GET_COMMAND. (line 6) * command-line arguments <3>: GET_COMMAND_ARGUMENT. (line 6) * command-line arguments <4>: IARGC. (line 6) * command-line arguments, number of: COMMAND_ARGUMENT_COUNT. (line 6) * command-line arguments, number of <1>: IARGC. (line 6) * COMMON: Volatile COMMON blocks. (line 6) * Compiler Directives: GNU Fortran Compiler Directives. (line 6) * compiler flags inquiry function: COMPILER_OPTIONS. (line 6) * COMPILER_OPTIONS: COMPILER_OPTIONS. (line 6) * COMPILER_VERSION: COMPILER_VERSION. (line 6) * compiler, name and version: COMPILER_VERSION. (line 6) * COMPLEX: COMPLEX. (line 6) * complex conjugate: CONJG. (line 6) * Complex function: Alternate complex function syntax. (line 6) * complex numbers, conversion to: CMPLX. (line 6) * complex numbers, conversion to <1>: COMPLEX. (line 6) * complex numbers, conversion to <2>: DCMPLX. (line 6) * complex numbers, imaginary part: AIMAG. (line 6) * complex numbers, real part: DREAL. (line 6) * complex numbers, real part <1>: REAL. (line 6) * conditional compilation: Fortran 95 status. (line 6) * Conditional compilation: Preprocessing Options. (line 6) * CONJG: CONJG. (line 6) * consistency, durability: Data consistency and durability. (line 6) * Contributing: Contributing. (line 6) * Contributors: Contributors. (line 6) * conversion: Error and Warning Options. (line 117) * conversion <1>: Error and Warning Options. (line 121) * conversion, to character: Character conversion. (line 6) * conversion, to character <1>: CHAR. (line 6) * conversion, to complex: CMPLX. (line 6) * conversion, to complex <1>: COMPLEX. (line 6) * conversion, to complex <2>: DCMPLX. (line 6) * conversion, to integer: Implicitly convert LOGICAL and INTEGER values. (line 6) * conversion, to integer <1>: IACHAR. (line 6) * conversion, to integer <2>: ICHAR. (line 6) * conversion, to integer <3>: INT. (line 6) * conversion, to integer <4>: INT2. (line 6) * conversion, to integer <5>: INT8. (line 6) * conversion, to logical: Implicitly convert LOGICAL and INTEGER values. (line 6) * conversion, to logical <1>: LOGICAL. (line 6) * conversion, to real: DBLE. (line 6) * conversion, to real <1>: REAL. (line 6) * conversion, to string: CTIME. (line 6) * CONVERT specifier: CONVERT specifier. (line 6) * core, dump: ABORT. (line 6) * COS: COS. (line 6) * COSD: COSD. (line 6) * COSH: COSH. (line 6) * cosine: COS. (line 6) * cosine, degrees: COSD. (line 6) * cosine, hyperbolic: COSH. (line 6) * cosine, hyperbolic, inverse: ACOSH. (line 6) * cosine, inverse: ACOS. (line 6) * cosine, inverse, degrees: ACOSD. (line 6) * COTAN: COTAN. (line 6) * COTAND: COTAND. (line 6) * cotangent: COTAN. (line 6) * cotangent, degrees: COTAND. (line 6) * COUNT: COUNT. (line 6) * CPP: Preprocessing Options. (line 6) * CPU_TIME: CPU_TIME. (line 6) * Credits: Contributors. (line 6) * CSHIFT: CSHIFT. (line 6) * CSIN: SIN. (line 6) * CSIND: SIND. (line 6) * CSQRT: SQRT. (line 6) * CTIME: CTIME. (line 6) * current date: DATE_AND_TIME. (line 6) * current date <1>: FDATE. (line 6) * current date <2>: IDATE. (line 6) * current time: DATE_AND_TIME. (line 6) * current time <1>: FDATE. (line 6) * current time <2>: ITIME. (line 6) * current time <3>: TIME. (line 6) * current time <4>: TIME8. (line 6) * DABS: ABS. (line 6) * DACOS: ACOS. (line 6) * DACOSD: ACOSD. (line 6) * DACOSH: ACOSH. (line 6) * DASIN: ASIN. (line 6) * DASIND: ASIND. (line 6) * DASINH: ASINH. (line 6) * DATAN: ATAN. (line 6) * DATAN2: ATAN2. (line 6) * DATAN2D: ATAN2D. (line 6) * DATAND: ATAND. (line 6) * DATANH: ATANH. (line 6) * DATE_AND_TIME: DATE_AND_TIME. (line 6) * date, current: DATE_AND_TIME. (line 6) * date, current <1>: FDATE. (line 6) * date, current <2>: IDATE. (line 6) * DBESJ0: BESSEL_J0. (line 6) * DBESJ1: BESSEL_J1. (line 6) * DBESJN: BESSEL_JN. (line 6) * DBESY0: BESSEL_Y0. (line 6) * DBESY1: BESSEL_Y1. (line 6) * DBESYN: BESSEL_YN. (line 6) * DBLE: DBLE. (line 6) * DCMPLX: DCMPLX. (line 6) * DCONJG: CONJG. (line 6) * DCOS: COS. (line 6) * DCOSD: COSD. (line 6) * DCOSH: COSH. (line 6) * DCOTAN: COTAN. (line 6) * DCOTAND: COTAND. (line 6) * DDIM: DIM. (line 6) * debugging information options: Debugging Options. (line 6) * debugging, preprocessor: Preprocessing Options. (line 56) * debugging, preprocessor <1>: Preprocessing Options. (line 65) * debugging, preprocessor <2>: Preprocessing Options. (line 71) * debugging, preprocessor <3>: Preprocessing Options. (line 74) * debugging, preprocessor <4>: Preprocessing Options. (line 81) * DECODE: ENCODE and DECODE statements. (line 6) * delayed execution: ALARM. (line 6) * delayed execution <1>: SLEEP. (line 6) * derived type interoperability with C: Derived Types and struct. (line 6) * developer options: Developer Options. (line 6) * DEXP: EXP. (line 6) * DFLOAT: REAL. (line 6) * DGAMMA: GAMMA. (line 6) * dialect options: Fortran Dialect Options. (line 6) * DIGITS: DIGITS. (line 6) * DIM: DIM. (line 6) * DIMAG: AIMAG. (line 6) * DINT: AINT. (line 6) * directive, INCLUDE: Directory Options. (line 6) * Directives: GNU Fortran Compiler Directives. (line 6) * directory, options: Directory Options. (line 6) * directory, search paths for inclusion: Directory Options. (line 13) * division, modulo: MODULO. (line 6) * division, remainder: MOD. (line 6) * DLGAMA: LOG_GAMMA. (line 6) * DLOG: LOG. (line 6) * DLOG10: LOG10. (line 6) * DMAX1: MAX. (line 6) * DMIN1: MIN. (line 6) * DMOD: MOD. (line 6) * DNINT: ANINT. (line 6) * dope vector: Further Interoperability of Fortran with C. (line 6) * dot product: DOT_PRODUCT. (line 6) * DOT_PRODUCT: DOT_PRODUCT. (line 6) * DPROD: DPROD. (line 6) * DREAL: DREAL. (line 6) * DSHIFTL: DSHIFTL. (line 6) * DSHIFTR: DSHIFTR. (line 6) * DSIGN: SIGN. (line 6) * DSIN: SIN. (line 6) * DSIND: SIND. (line 6) * DSINH: SINH. (line 6) * DSQRT: SQRT. (line 6) * DTAN: TAN. (line 6) * DTAND: TAND. (line 6) * DTANH: TANH. (line 6) * DTIME: DTIME. (line 6) * dummy argument, unused: Error and Warning Options. (line 229) * elapsed time: DTIME. (line 6) * elapsed time <1>: SECNDS. (line 6) * elapsed time <2>: SECOND. (line 6) * Elimination of functions with identical argument lists: Code Gen Options. (line 462) * ENCODE: ENCODE and DECODE statements. (line 6) * environment variable: Environment Variables. (line 6) * environment variable <1>: Runtime. (line 6) * environment variable <2>: GETENV. (line 6) * environment variable <3>: GET_ENVIRONMENT_VARIABLE. (line 6) * EOF: Read/Write after EOF marker. (line 6) * EOSHIFT: EOSHIFT. (line 6) * EPSILON: EPSILON. (line 6) * ERF: ERF. (line 6) * ERFC: ERFC. (line 6) * ERFC_SCALED: ERFC_SCALED. (line 6) * error function: ERF. (line 6) * error function, complementary: ERFC. (line 6) * error function, complementary, exponentially-scaled: ERFC_SCALED. (line 6) * errors, limiting: Error and Warning Options. (line 26) * escape characters: Fortran Dialect Options. (line 113) * ETIME: ETIME. (line 6) * Euclidean distance: HYPOT. (line 6) * Euclidean vector norm: NORM2. (line 6) * EVENT_QUERY: EVENT_QUERY. (line 6) * Events, EVENT_QUERY: EVENT_QUERY. (line 6) * EXECUTE_COMMAND_LINE: EXECUTE_COMMAND_LINE. (line 6) * EXIT: EXIT. (line 6) * EXP: EXP. (line 6) * EXPONENT: EXPONENT. (line 6) * exponent: Default exponents. (line 6) * exponential function: EXP. (line 6) * exponential function, inverse: LOG. (line 6) * exponential function, inverse <1>: LOG10. (line 6) * expression size: C_SIZEOF. (line 6) * expression size <1>: SIZEOF. (line 6) * EXTENDS_TYPE_OF: EXTENDS_TYPE_OF. (line 6) * extensions: Extensions. (line 6) * extensions, implemented: Extensions implemented in GNU Fortran. (line 6) * extensions, not implemented: Extensions not implemented in GNU Fortran. (line 6) * extra warnings: Error and Warning Options. (line 131) * f2c calling convention: Code Gen Options. (line 27) * f2c calling convention <1>: Code Gen Options. (line 113) * Factorial function: GAMMA. (line 6) * FDATE: FDATE. (line 6) * FDL, GNU Free Documentation License: GNU Free Documentation License. (line 6) * FGET: FGET. (line 6) * FGETC: FGETC. (line 6) * file format, fixed: Fortran Dialect Options. (line 9) * file format, fixed <1>: Fortran Dialect Options. (line 130) * file format, free: Fortran Dialect Options. (line 9) * file format, free <1>: Fortran Dialect Options. (line 152) * file operation, file number: FNUM. (line 6) * file operation, flush: FLUSH. (line 6) * file operation, position: FSEEK. (line 6) * file operation, position <1>: FTELL. (line 6) * file operation, read character: FGET. (line 6) * file operation, read character <1>: FGETC. (line 6) * file operation, seek: FSEEK. (line 6) * file operation, write character: FPUT. (line 6) * file operation, write character <1>: FPUTC. (line 6) * file system, access mode: ACCESS. (line 6) * file system, change access mode: CHMOD. (line 6) * file system, create link: LINK. (line 6) * file system, create link <1>: SYMLNK. (line 6) * file system, file creation mask: UMASK. (line 6) * file system, file status: FSTAT. (line 6) * file system, file status <1>: LSTAT. (line 6) * file system, file status <2>: STAT. (line 6) * file system, hard link: LINK. (line 6) * file system, remove file: UNLINK. (line 6) * file system, rename file: RENAME. (line 6) * file system, soft link: SYMLNK. (line 6) * file, symbolic link: File operations on symbolic links. (line 6) * file, unformatted sequential: File format of unformatted sequential files. (line 6) * FINDLOC: FINDLOC. (line 6) * findloc: FINDLOC. (line 6) * flags inquiry function: COMPILER_OPTIONS. (line 6) * FLOAT: REAL. (line 6) * FLOATI: REAL. (line 6) * floating point, exponent: EXPONENT. (line 6) * floating point, fraction: FRACTION. (line 6) * floating point, nearest different: NEAREST. (line 6) * floating point, relative spacing: RRSPACING. (line 6) * floating point, relative spacing <1>: SPACING. (line 6) * floating point, scale: SCALE. (line 6) * floating point, set exponent: SET_EXPONENT. (line 6) * FLOATJ: REAL. (line 6) * FLOATK: REAL. (line 6) * FLOOR: FLOOR. (line 6) * floor: AINT. (line 6) * floor <1>: FLOOR. (line 6) * FLUSH: FLUSH. (line 6) * FNUM: FNUM. (line 6) * form feed whitespace: Form feed as whitespace. (line 6) * FORMAT: Variable FORMAT expressions. (line 6) * FPP: Preprocessing Options. (line 6) * FPUT: FPUT. (line 6) * FPUTC: FPUTC. (line 6) * FRACTION: FRACTION. (line 6) * FREE: FREE. (line 6) * Front-end optimization: Code Gen Options. (line 470) * FSEEK: FSEEK. (line 6) * FSTAT: FSTAT. (line 6) * FTELL: FTELL. (line 6) * function elimination: Error and Warning Options. (line 246) * function interoperability with C: Interoperable Subroutines and Functions. (line 6) * Further Interoperability of Fortran with C: Further Interoperability of Fortran with C. (line 6) * Future Fortran versions: Experimental features for future Fortran versions. (line 6) * g77 calling convention: Code Gen Options. (line 27) * g77 calling convention <1>: Code Gen Options. (line 113) * GAMMA: GAMMA. (line 6) * Gamma function: GAMMA. (line 6) * Gamma function, logarithm of: LOG_GAMMA. (line 6) * GCC: GNU Fortran and GCC. (line 6) * Generating C prototypes from external procedures: Interoperability Options. (line 24) * Generating C prototypes from Fortran BIND(C) enteties: Interoperability Options. (line 6) * GERROR: GERROR. (line 6) * GET_COMMAND: GET_COMMAND. (line 6) * GET_COMMAND_ARGUMENT: GET_COMMAND_ARGUMENT. (line 6) * GET_ENVIRONMENT_VARIABLE: GET_ENVIRONMENT_VARIABLE. (line 6) * GETARG: GETARG. (line 6) * GETCWD: GETCWD. (line 6) * GETENV: GETENV. (line 6) * GETGID: GETGID. (line 6) * GETLOG: GETLOG. (line 6) * GETPID: GETPID. (line 6) * GETUID: GETUID. (line 6) * GMTIME: GMTIME. (line 6) * GNU Compiler Collection: GNU Fortran and GCC. (line 6) * GNU Fortran command options: Invoking GNU Fortran. (line 6) * GNU Fortran Compiler Directives: GNU Fortran Compiler Directives. (line 6) * Hollerith constants: Hollerith constants support. (line 6) * HOSTNM: HOSTNM. (line 6) * HUGE: HUGE. (line 6) * hyperbolic cosine: COSH. (line 6) * hyperbolic function, cosine: COSH. (line 6) * hyperbolic function, cosine, inverse: ACOSH. (line 6) * hyperbolic function, sine: SINH. (line 6) * hyperbolic function, sine, inverse: ASINH. (line 6) * hyperbolic function, tangent: TANH. (line 6) * hyperbolic function, tangent, inverse: ATANH. (line 6) * hyperbolic sine: SINH. (line 6) * hyperbolic tangent: TANH. (line 6) * HYPOT: HYPOT. (line 6) * I/O item lists: I/O item lists. (line 6) * I/O specifiers: Extended I/O specifiers. (line 6) * IABS: ABS. (line 6) * IACHAR: IACHAR. (line 6) * IALL: IALL. (line 6) * IAND: IAND. (line 6) * IANY: IANY. (line 6) * IARGC: IARGC. (line 6) * IBCLR: IBCLR. (line 6) * IBITS: IBITS. (line 6) * IBSET: IBSET. (line 6) * ICHAR: ICHAR. (line 6) * IDATE: IDATE. (line 6) * IDIM: DIM. (line 6) * IDINT: INT. (line 6) * IDNINT: NINT. (line 6) * IEEE, ISNAN: ISNAN. (line 6) * IEOR: IEOR. (line 6) * IERRNO: IERRNO. (line 6) * IFIX: INT. (line 6) * IIABS: ABS. (line 6) * IIAND: IAND. (line 6) * IIBCLR: IBCLR. (line 6) * IIBITS: IBITS. (line 6) * IIBSET: IBSET. (line 6) * IIEOR: IEOR. (line 6) * IIOR: IOR. (line 6) * IISHFT: ISHFT. (line 6) * IISHFTC: ISHFTC. (line 6) * IMAG: AIMAG. (line 6) * IMAGE_INDEX: IMAGE_INDEX. (line 6) * images, cosubscript to image index conversion: IMAGE_INDEX. (line 6) * images, index of this image: THIS_IMAGE. (line 6) * images, number of: NUM_IMAGES. (line 6) * IMAGPART: AIMAG. (line 6) * IMOD: MOD. (line 6) * IMVBITS: MVBITS. (line 6) * INCLUDE directive: Directory Options. (line 6) * inclusion, directory search paths for: Directory Options. (line 13) * INDEX: INDEX intrinsic. (line 6) * INOT: NOT. (line 6) * input/output, asynchronous: Asynchronous I/O. (line 6) * INT: INT. (line 6) * INT2: INT2. (line 6) * INT8: INT8. (line 6) * integer kind: SELECTED_INT_KIND. (line 6) * integer overflow: Behavior on integer overflow. (line 6) * Interoperability: Mixed-Language Programming. (line 6) * interoperability with C: Interoperability with C. (line 6) * interoperability, derived type and struct: Derived Types and struct. (line 6) * interoperability, intrinsic type: Intrinsic Types. (line 6) * interoperability, subroutine and function: Interoperable Subroutines and Functions. (line 6) * interoperability, variable: Interoperable Global Variables. (line 6) * intrinsic: Error and Warning Options. (line 218) * intrinsic <1>: Error and Warning Options. (line 225) * intrinsic Modules: Intrinsic Modules. (line 6) * intrinsic procedures: Intrinsic Procedures. (line 6) * intrinsic type interoperability with C: Intrinsic Types. (line 6) * intrinsics, integer: Type variants for integer intrinsics. (line 6) * Introduction: Top. (line 6) * inverse hyperbolic cosine: ACOSH. (line 6) * inverse hyperbolic sine: ASINH. (line 6) * inverse hyperbolic tangent: ATANH. (line 6) * IOR: IOR. (line 6) * IOSTAT, end of file: IS_IOSTAT_END. (line 6) * IOSTAT, end of record: IS_IOSTAT_EOR. (line 6) * IPARITY: IPARITY. (line 6) * IRAND: IRAND. (line 6) * IS_IOSTAT_END: IS_IOSTAT_END. (line 6) * IS_IOSTAT_EOR: IS_CONTIGUOUS. (line 6) * IS_IOSTAT_EOR <1>: IS_IOSTAT_EOR. (line 6) * ISATTY: ISATTY. (line 6) * ISHFT: ISHFT. (line 6) * ISHFTC: ISHFTC. (line 6) * ISIGN: SIGN. (line 6) * ISNAN: ISNAN. (line 6) * ITIME: ITIME. (line 6) * IVDEP directive: IVDEP directive. (line 6) * JIABS: ABS. (line 6) * JIAND: IAND. (line 6) * JIBCLR: IBCLR. (line 6) * JIBITS: IBITS. (line 6) * JIBSET: IBSET. (line 6) * JIEOR: IEOR. (line 6) * JIOR: IOR. (line 6) * JISHFT: ISHFT. (line 6) * JISHFTC: ISHFTC. (line 6) * JMOD: MOD. (line 6) * JMVBITS: MVBITS. (line 6) * JNOT: NOT. (line 6) * KIABS: ABS. (line 6) * KIAND: IAND. (line 6) * KIBCLR: IBCLR. (line 6) * KIBITS: IBITS. (line 6) * KIBSET: IBSET. (line 6) * KIEOR: IEOR. (line 6) * KILL: KILL. (line 6) * kind: KIND Type Parameters. (line 6) * KIND: KIND. (line 6) * kind <1>: KIND. (line 6) * kind, character: SELECTED_CHAR_KIND. (line 6) * kind, integer: SELECTED_INT_KIND. (line 6) * kind, logical: SELECTED_LOGICAL_KIND. (line 6) * kind, old-style: Old-style kind specifications. (line 6) * kind, real: SELECTED_REAL_KIND. (line 6) * kind, unsigned: SELECTED_UNSIGNED_KIND. (line 6) * KIOR: IOR. (line 6) * KISHFT: ISHFT. (line 6) * KISHFTC: ISHFTC. (line 6) * KMOD: MOD. (line 6) * KMVBITS: MVBITS. (line 6) * KNOT: NOT. (line 6) * L2 vector norm: NORM2. (line 6) * language, dialect options: Fortran Dialect Options. (line 6) * LBOUND: LBOUND. (line 6) * LCOBOUND: LCOBOUND. (line 6) * LEADZ: LEADZ. (line 6) * left shift, combined: DSHIFTL. (line 6) * LEN: LEN. (line 6) * LEN_TRIM: LEN_TRIM. (line 6) * lexical comparison of strings: LGE. (line 6) * lexical comparison of strings <1>: LGT. (line 6) * lexical comparison of strings <2>: LLE. (line 6) * lexical comparison of strings <3>: LLT. (line 6) * LGAMMA: LOG_GAMMA. (line 6) * LGE: LGE. (line 6) * LGT: LGT. (line 6) * libf2c calling convention: Code Gen Options. (line 27) * libf2c calling convention <1>: Code Gen Options. (line 113) * libgfortran initialization, set_args: _gfortran_set_args. (line 6) * libgfortran initialization, set_convert: _gfortran_set_convert. (line 6) * libgfortran initialization, set_fpe: _gfortran_set_fpe. (line 6) * libgfortran initialization, set_max_subrecord_length: _gfortran_set_max_subrecord_length. (line 6) * libgfortran initialization, set_options: _gfortran_set_options. (line 6) * libgfortran initialization, set_record_marker: _gfortran_set_record_marker. (line 6) * limits, largest number: HUGE. (line 6) * limits, smallest number: TINY. (line 6) * LINK: LINK. (line 6) * linking, static: Link Options. (line 6) * LLE: LLE. (line 6) * LLT: LLT. (line 6) * LNBLNK: LNBLNK. (line 6) * LOC: %LOC as an rvalue. (line 6) * LOC <1>: LOC. (line 6) * location of a variable in memory: LOC. (line 6) * LOG: LOG. (line 6) * LOG_GAMMA: LOG_GAMMA. (line 6) * LOG10: LOG10. (line 6) * logarithm function: LOG. (line 6) * logarithm function with base 10: LOG10. (line 6) * logarithm function, inverse: EXP. (line 6) * LOGICAL: LOGICAL. (line 6) * logical and, bitwise: AND. (line 6) * logical and, bitwise <1>: IAND. (line 6) * logical exclusive or, bitwise: IEOR. (line 6) * logical exclusive or, bitwise <1>: XOR. (line 6) * logical kind: SELECTED_LOGICAL_KIND. (line 6) * logical not, bitwise: NOT. (line 6) * logical or, bitwise: IOR. (line 6) * logical or, bitwise <1>: OR. (line 6) * logical, bitwise: Bitwise logical operators. (line 6) * logical, variable representation: Internal representation of LOGICAL variables. (line 6) * login name: GETLOG. (line 6) * loop interchange, Fortran: Code Gen Options. (line 483) * loop interchange, warning: Error and Warning Options. (line 136) * LSHIFT: LSHIFT. (line 6) * LSTAT: LSTAT. (line 6) * LTIME: LTIME. (line 6) * Main Program: Non-Fortran Main Program. (line 6) * MALLOC: MALLOC. (line 6) * MAP: UNION and MAP. (line 6) * mask, left justified: MASKL. (line 6) * mask, left justified <1>: UMASKL. (line 6) * mask, right justified: MASKR. (line 6) * mask, right justified <1>: UMASKR. (line 6) * MASKL: MASKL. (line 6) * MASKR: MASKR. (line 6) * MATMUL: MATMUL. (line 6) * matrix multiplication: MATMUL. (line 6) * matrix, transpose: TRANSPOSE. (line 6) * MAX: MAX. (line 6) * MAX, MIN, NaN: MAX and MIN intrinsics with REAL NaN arguments. (line 6) * MAX0: MAX. (line 6) * MAX1: MAX. (line 6) * MAXEXPONENT: MAXEXPONENT. (line 6) * maximum value: MAX. (line 6) * maximum value <1>: MAXVAL. (line 6) * MAXLOC: MAXLOC. (line 6) * MAXVAL: MAXVAL. (line 6) * MCLOCK: MCLOCK. (line 6) * MCLOCK8: MCLOCK8. (line 6) * memory checking: Code Gen Options. (line 143) * MERGE: MERGE. (line 6) * MERGE_BITS: MERGE_BITS. (line 6) * messages, error: Error and Warning Options. (line 6) * messages, warning: Error and Warning Options. (line 6) * MIN: MIN. (line 6) * MIN0: MIN. (line 6) * MIN1: MIN. (line 6) * MINEXPONENT: MINEXPONENT. (line 6) * minimum value: MIN. (line 6) * minimum value <1>: MINVAL. (line 6) * MINLOC: MINLOC. (line 6) * MINVAL: MINVAL. (line 6) * Mixed-language programming: Mixed-Language Programming. (line 6) * MOD: MOD. (line 6) * model representation, base: RADIX. (line 6) * model representation, epsilon: EPSILON. (line 6) * model representation, largest number: HUGE. (line 6) * model representation, maximum exponent: MAXEXPONENT. (line 6) * model representation, minimum exponent: MINEXPONENT. (line 6) * model representation, precision: PRECISION. (line 6) * model representation, radix: RADIX. (line 6) * model representation, range: RANGE. (line 6) * model representation, significant digits: DIGITS. (line 6) * model representation, smallest number: TINY. (line 6) * module entities: Fortran Dialect Options. (line 125) * module search path: Directory Options. (line 13) * module search path <1>: Directory Options. (line 28) * module search path <2>: Directory Options. (line 35) * MODULO: MODULO. (line 6) * modulo: MODULO. (line 6) * MOVE_ALLOC: MOVE_ALLOC. (line 6) * moving allocation: MOVE_ALLOC. (line 6) * multiply array elements: PRODUCT. (line 6) * MVBITS: MVBITS. (line 6) * NAME: OPEN( ... NAME=). (line 6) * Namelist: Extensions to namelist. (line 6) * Naming conventions: Naming conventions. (line 6) * natural logarithm function: LOG. (line 6) * NEAREST: NEAREST. (line 6) * NEW_LINE: NEW_LINE. (line 6) * newline: NEW_LINE. (line 6) * NINT: NINT. (line 6) * Non-Fortran Main Program: Non-Fortran Main Program. (line 6) * norm, Euclidean: NORM2. (line 6) * NORM2: NORM2. (line 6) * NOSHARED: Extended I/O specifiers. (line 6) * NOT: NOT. (line 6) * NOVECTOR directive: NOVECTOR directive. (line 6) * NULL: NULL. (line 6) * NUM_IMAGES: NUM_IMAGES. (line 6) * open, action: Files opened without an explicit ACTION= specifier. (line 6) * OpenACC: OpenACC. (line 6) * OpenACC accelerator programming: Fortran Dialect Options. (line 172) * OpenMP: OpenMP. (line 6) * OpenMP Allocators: Fortran Dialect Options. (line 192) * OpenMP parallel: Fortran Dialect Options. (line 181) * OpenMP SIMD: Fortran Dialect Options. (line 210) * operators, unary: Unary operators. (line 6) * operators, xor: .XOR. operator. (line 6) * options inquiry function: COMPILER_OPTIONS. (line 6) * options, code generation: Code Gen Options. (line 6) * options, debugging: Debugging Options. (line 6) * options, debugging <1>: Developer Options. (line 6) * options, dialect: Fortran Dialect Options. (line 6) * options, directory search: Directory Options. (line 6) * options, errors: Error and Warning Options. (line 6) * options, Fortran dialect: Fortran Dialect Options. (line 9) * options, gfortran command: Invoking GNU Fortran. (line 6) * options, linking: Link Options. (line 6) * options, negative forms: Invoking GNU Fortran. (line 13) * options, preprocessor: Preprocessing Options. (line 6) * options, real kind type promotion: Fortran Dialect Options. (line 287) * options, run-time: Code Gen Options. (line 6) * options, runtime: Runtime Options. (line 6) * options, warnings: Error and Warning Options. (line 6) * OR: OR. (line 6) * OUT_OF_RANGE: OUT_OF_RANGE. (line 6) * output, newline: NEW_LINE. (line 6) * overflow handling: Behavior on integer overflow. (line 6) * PACK: PACK. (line 6) * PARAMETER: Legacy PARAMETER statements. (line 6) * PARITY: PARITY. (line 6) * Parity: PARITY. (line 6) * parity: POPPAR. (line 6) * paths, search: Directory Options. (line 13) * paths, search <1>: Directory Options. (line 28) * paths, search <2>: Directory Options. (line 35) * PERROR: PERROR. (line 6) * pointer checking: Code Gen Options. (line 143) * pointer, C address of pointers: C_F_PROCPOINTER. (line 6) * pointer, C address of procedures: C_FUNLOC. (line 6) * pointer, C association status: C_ASSOCIATED. (line 6) * pointer, convert C to Fortran: C_F_POINTER. (line 6) * pointer, Cray: Cray pointers. (line 6) * pointer, cray: FREE. (line 6) * pointer, cray <1>: MALLOC. (line 6) * pointer, disassociated: NULL. (line 6) * pointer, status: ASSOCIATED. (line 6) * pointer, status <1>: NULL. (line 6) * pointers, C: Working with C Pointers. (line 6) * POPCNT: POPCNT. (line 6) * POPPAR: POPPAR. (line 6) * positive difference: DIM. (line 6) * PRECISION: PRECISION. (line 6) * Preprocessing: Preprocessing Options. (line 6) * preprocessing, assertion: Preprocessing Options. (line 143) * preprocessing, assertion <1>: Preprocessing Options. (line 149) * preprocessing, define macros: Preprocessing Options. (line 181) * preprocessing, define macros <1>: Preprocessing Options. (line 184) * preprocessing, include path: Preprocessing Options. (line 99) * preprocessing, include path <1>: Preprocessing Options. (line 106) * preprocessing, include path <2>: Preprocessing Options. (line 110) * preprocessing, include path <3>: Preprocessing Options. (line 115) * preprocessing, include path <4>: Preprocessing Options. (line 119) * preprocessing, include path <5>: Preprocessing Options. (line 126) * preprocessing, keep comments: Preprocessing Options. (line 152) * preprocessing, keep comments <1>: Preprocessing Options. (line 167) * preprocessing, no linemarkers: Preprocessing Options. (line 209) * preprocessing, undefine macros: Preprocessing Options. (line 215) * preprocessor: Preprocessing Options. (line 6) * preprocessor, debugging: Preprocessing Options. (line 56) * preprocessor, debugging <1>: Preprocessing Options. (line 65) * preprocessor, debugging <2>: Preprocessing Options. (line 71) * preprocessor, debugging <3>: Preprocessing Options. (line 74) * preprocessor, debugging <4>: Preprocessing Options. (line 81) * preprocessor, disable: Preprocessing Options. (line 41) * preprocessor, enable: Preprocessing Options. (line 41) * preprocessor, include file handling: Preprocessing Options. (line 6) * preprocessor, working directory: Preprocessing Options. (line 85) * PRESENT: PRESENT. (line 6) * private: Fortran Dialect Options. (line 125) * procedure interoperability with C: Interoperable Subroutines and Functions. (line 6) * procedure pointer, convert C to Fortran: C_LOC. (line 6) * process ID: GETPID. (line 6) * PRODUCT: PRODUCT. (line 6) * product, double-precision: DPROD. (line 6) * product, matrix: MATMUL. (line 6) * product, vector: DOT_PRODUCT. (line 6) * program termination: EXIT. (line 6) * program termination, with core dump: ABORT. (line 6) * prototypes: Generating C prototypes from Fortran. (line 6) * Q edit descriptor: Q edit descriptor. (line 6) * Q exponent-letter: Q exponent-letter. (line 6) * RADIX: RADIX. (line 6) * radix, real: SELECTED_REAL_KIND. (line 6) * RAN: RAN. (line 6) * RAND: RAND. (line 6) * random number generation: IRAND. (line 6) * random number generation <1>: RAN. (line 6) * random number generation <2>: RAND. (line 6) * random number generation <3>: RANDOM_NUMBER. (line 6) * random number generation, initialization: RANDOM_INIT. (line 6) * random number generation, seeding: RANDOM_SEED. (line 6) * random number generation, seeding <1>: SRAND. (line 6) * RANDOM_INIT: RANDOM_INIT. (line 6) * RANDOM_NUMBER: RANDOM_NUMBER. (line 6) * RANDOM_SEED: RANDOM_SEED. (line 6) * RANGE: RANGE. (line 6) * range check, numerical conversion: OUT_OF_RANGE. (line 6) * range checking: Code Gen Options. (line 143) * RANK: RANK. (line 6) * rank: RANK. (line 6) * read character, stream mode: FGET. (line 6) * read character, stream mode <1>: FGETC. (line 6) * READONLY: Extended I/O specifiers. (line 6) * REAL: REAL. (line 6) * real kind: SELECTED_REAL_KIND. (line 6) * real number, exponent: EXPONENT. (line 6) * real number, fraction: FRACTION. (line 6) * real number, nearest different: NEAREST. (line 6) * real number, relative spacing: RRSPACING. (line 6) * real number, relative spacing <1>: SPACING. (line 6) * real number, scale: SCALE. (line 6) * real number, set exponent: SET_EXPONENT. (line 6) * Reallocate the LHS in assignments: Code Gen Options. (line 456) * Reallocate the LHS in assignments, notification: Error and Warning Options. (line 251) * REALPART: REAL. (line 6) * reassociation of parenthesized expressions: Code Gen Options. (line 447) * RECORD: STRUCTURE and RECORD. (line 6) * record marker: File format of unformatted sequential files. (line 6) * Reduction, XOR: PARITY. (line 6) * remainder: MOD. (line 6) * RENAME: RENAME. (line 6) * repacking arrays: Code Gen Options. (line 287) * REPEAT: REPEAT. (line 6) * RESHAPE: RESHAPE. (line 6) * REWIND: Read/Write after EOF marker. (line 6) * right shift, combined: DSHIFTR. (line 6) * root: SQRT. (line 6) * rounding, ceiling: ANINT. (line 6) * rounding, ceiling <1>: CEILING. (line 6) * rounding, floor: AINT. (line 6) * rounding, floor <1>: FLOOR. (line 6) * rounding, nearest whole number: NINT. (line 6) * RRSPACING: RRSPACING. (line 6) * RSHIFT: RSHIFT. (line 6) * run-time checking: Code Gen Options. (line 143) * SAME_TYPE_AS: SAME_TYPE_AS. (line 6) * SAVE statement: Code Gen Options. (line 14) * SCALE: SCALE. (line 6) * SCAN: SCAN. (line 6) * search path: Directory Options. (line 6) * search paths, for included files: Directory Options. (line 13) * SECNDS: SECNDS. (line 6) * SECOND: SECOND. (line 6) * seeding a random number generator: RANDOM_SEED. (line 6) * seeding a random number generator <1>: SRAND. (line 6) * SELECTED_CHAR_KIND: SELECTED_CHAR_KIND. (line 6) * SELECTED_INT_KIND: SELECTED_INT_KIND. (line 6) * SELECTED_LOGICAL_KIND: SELECTED_LOGICAL_KIND. (line 6) * SELECTED_REAL_KIND: SELECTED_REAL_KIND. (line 6) * SELECTED_UNSIGNED_KIND: SELECTED_UNSIGNED_KIND. (line 6) * sequential, unformatted: File format of unformatted sequential files. (line 6) * SET_EXPONENT: SET_EXPONENT. (line 6) * SHAPE: SHAPE. (line 6) * SHARE: Extended I/O specifiers. (line 6) * SHARED: Extended I/O specifiers. (line 6) * shift, left: DSHIFTL. (line 6) * shift, left <1>: SHIFTL. (line 6) * shift, right: DSHIFTR. (line 6) * shift, right <1>: SHIFTR. (line 6) * shift, right with fill: SHIFTA. (line 6) * SHIFTA: SHIFTA. (line 6) * SHIFTL: SHIFTL. (line 6) * SHIFTR: SHIFTR. (line 6) * SIGN: SIGN. (line 6) * sign copying: SIGN. (line 6) * SIGNAL: SIGNAL. (line 6) * SIMD: Fortran Dialect Options. (line 210) * SIN: SIN. (line 6) * SIND: SIND. (line 6) * sine: SIN. (line 6) * sine, degrees: SIND. (line 6) * sine, hyperbolic: SINH. (line 6) * sine, hyperbolic, inverse: ASINH. (line 6) * sine, inverse: ASIN. (line 6) * sine, inverse, degrees: ASIND. (line 6) * SINH: SINH. (line 6) * SIZE: SIZE. (line 6) * size of a variable, in bits: BIT_SIZE. (line 6) * size of an expression: C_SIZEOF. (line 6) * size of an expression <1>: SIZEOF. (line 6) * SIZEOF: SIZEOF. (line 6) * SLEEP: SLEEP. (line 6) * SNGL: REAL. (line 6) * SPACING: SPACING. (line 6) * SPREAD: SPREAD. (line 6) * SQRT: SQRT. (line 6) * square-root: SQRT. (line 6) * SRAND: SRAND. (line 6) * Standards: Standards. (line 6) * STAT: STAT. (line 6) * statement, SAVE: Code Gen Options. (line 14) * STATIC: AUTOMATIC and STATIC attributes. (line 6) * storage size: STORAGE_SIZE. (line 6) * STORAGE_SIZE: STORAGE_SIZE. (line 6) * stream mode, read character: FGET. (line 6) * stream mode, read character <1>: FGETC. (line 6) * stream mode, write character: FPUT. (line 6) * stream mode, write character <1>: FPUTC. (line 6) * string, adjust left: ADJUSTL. (line 6) * string, adjust right: ADJUSTR. (line 6) * string, comparison: LGE. (line 6) * string, comparison <1>: LGT. (line 6) * string, comparison <2>: LLE. (line 6) * string, comparison <3>: LLT. (line 6) * string, concatenate: REPEAT. (line 6) * string, find missing set: VERIFY. (line 6) * string, find non-blank character: LNBLNK. (line 6) * string, find subset: SCAN. (line 6) * string, find substring: INDEX intrinsic. (line 6) * string, length: LEN. (line 6) * string, length, without trailing whitespace: LEN_TRIM. (line 6) * string, remove trailing whitespace: TRIM. (line 6) * string, repeat: REPEAT. (line 6) * strings, varying length: Fortran 95 status. (line 6) * STRUCTURE: STRUCTURE and RECORD. (line 6) * structure packing: Code Gen Options. (line 281) * subrecord: File format of unformatted sequential files. (line 6) * subroutine interoperability with C: Interoperable Subroutines and Functions. (line 6) * subscript checking: Code Gen Options. (line 143) * substring position: INDEX intrinsic. (line 6) * SUM: SUM. (line 6) * sum array elements: SUM. (line 6) * suppressing warnings: Error and Warning Options. (line 6) * symbol names: Fortran Dialect Options. (line 107) * symbol names, transforming: Code Gen Options. (line 56) * symbol names, transforming <1>: Code Gen Options. (line 113) * symbol names, underscores: Code Gen Options. (line 56) * symbol names, underscores <1>: Code Gen Options. (line 113) * SYMLNK: SYMLNK. (line 6) * syntax checking: Error and Warning Options. (line 32) * SYSTEM: SYSTEM. (line 6) * SYSTEM_CLOCK: SYSTEM_CLOCK. (line 6) * system, error handling: GERROR. (line 6) * system, error handling <1>: IERRNO. (line 6) * system, error handling <2>: PERROR. (line 6) * system, group ID: GETGID. (line 6) * system, host name: HOSTNM. (line 6) * system, login name: GETLOG. (line 6) * system, process ID: GETPID. (line 6) * system, signal handling: SIGNAL. (line 6) * system, system call: EXECUTE_COMMAND_LINE. (line 6) * system, system call <1>: SYSTEM. (line 6) * system, terminal: ISATTY. (line 6) * system, terminal <1>: TTYNAM. (line 6) * system, user ID: GETUID. (line 6) * system, working directory: CHDIR. (line 6) * system, working directory <1>: GETCWD. (line 6) * tabulators: Error and Warning Options. (line 201) * TAN: TAN. (line 6) * TAND: TAND. (line 6) * tangent: TAN. (line 6) * tangent, degrees: TAND. (line 6) * tangent, hyperbolic: TANH. (line 6) * tangent, hyperbolic, inverse: ATANH. (line 6) * tangent, inverse: ATAN. (line 6) * tangent, inverse <1>: ATAN2. (line 6) * tangent, inverse, degrees: ATAND. (line 6) * tangent, inverse, degrees <1>: ATAN2D. (line 6) * TANH: TANH. (line 6) * terminate program: EXIT. (line 6) * terminate program, with core dump: ABORT. (line 6) * THIS_IMAGE: THIS_IMAGE. (line 6) * thread-safety, threads: Thread-safety of the runtime library. (line 6) * TIME: TIME. (line 6) * time, clock ticks: MCLOCK. (line 6) * time, clock ticks <1>: MCLOCK8. (line 6) * time, clock ticks <2>: SYSTEM_CLOCK. (line 6) * time, conversion to GMT info: GMTIME. (line 6) * time, conversion to local time info: LTIME. (line 6) * time, conversion to string: CTIME. (line 6) * time, current: DATE_AND_TIME. (line 6) * time, current <1>: FDATE. (line 6) * time, current <2>: ITIME. (line 6) * time, current <3>: TIME. (line 6) * time, current <4>: TIME8. (line 6) * time, elapsed: CPU_TIME. (line 6) * time, elapsed <1>: DTIME. (line 6) * time, elapsed <2>: ETIME. (line 6) * time, elapsed <3>: SECNDS. (line 6) * time, elapsed <4>: SECOND. (line 6) * TIME8: TIME8. (line 6) * TINY: TINY. (line 6) * trace: Debugging Options. (line 64) * TRAILZ: TRAILZ. (line 6) * TRANSFER: TRANSFER. (line 6) * transforming symbol names: Code Gen Options. (line 56) * transforming symbol names <1>: Code Gen Options. (line 113) * TRANSPOSE: TRANSPOSE. (line 6) * transpose: TRANSPOSE. (line 6) * trigonometric function, cosine: COS. (line 6) * trigonometric function, cosine, degrees: COSD. (line 6) * trigonometric function, cosine, inverse: ACOS. (line 6) * trigonometric function, cosine, inverse, degrees: ACOSD. (line 6) * trigonometric function, cotangent: COTAN. (line 6) * trigonometric function, cotangent, degrees: COTAND. (line 6) * trigonometric function, sine: SIN. (line 6) * trigonometric function, sine, degrees: SIND. (line 6) * trigonometric function, sine, inverse: ASIN. (line 6) * trigonometric function, sine, inverse, degrees: ASIND. (line 6) * trigonometric function, tangent: TAN. (line 6) * trigonometric function, tangent, degrees: TAND. (line 6) * trigonometric function, tangent, inverse: ATAN. (line 6) * trigonometric function, tangent, inverse <1>: ATAN2. (line 6) * trigonometric function, tangent, inverse, degrees: ATAND. (line 6) * trigonometric function, tangent, inverse, degrees <1>: ATAN2D. (line 6) * TRIM: TRIM. (line 6) * TS 29113: Further Interoperability of Fortran with C. (line 6) * TTYNAM: TTYNAM. (line 6) * type alias print: TYPE as an alias for PRINT. (line 6) * type cast: TRANSFER. (line 6) * UBOUND: UBOUND. (line 6) * UCOBOUND: UCOBOUND. (line 6) * UINT: UINT. (line 6) * UMASK: UMASK. (line 6) * UMASKL: UMASKL. (line 6) * UMASKR: UMASKR. (line 6) * underflow: Error and Warning Options. (line 214) * underscore: Code Gen Options. (line 56) * underscore <1>: Code Gen Options. (line 113) * unformatted sequential: File format of unformatted sequential files. (line 6) * UNION: UNION and MAP. (line 6) * UNLINK: UNLINK. (line 6) * UNPACK: UNPACK. (line 6) * UNROLL directive: UNROLL directive. (line 6) * Unsigned integers: Unsigned integers. (line 6) * unsigned kind: SELECTED_UNSIGNED_KIND. (line 6) * unused dummy argument: Error and Warning Options. (line 229) * unused parameter: Error and Warning Options. (line 233) * user id: GETUID. (line 6) * variable attributes: AUTOMATIC and STATIC attributes. (line 6) * variable interoperability with C: Interoperable Global Variables. (line 6) * Varying length strings: Fortran 95 status. (line 6) * VECTOR directive: VECTOR directive. (line 6) * vector product: DOT_PRODUCT. (line 6) * VERIFY: VERIFY. (line 6) * version of the compiler: COMPILER_VERSION. (line 6) * VOLATILE: Volatile COMMON blocks. (line 6) * warning, C binding type: Error and Warning Options. (line 101) * warnings, aliasing: Error and Warning Options. (line 70) * warnings, alignment of COMMON blocks: Error and Warning Options. (line 240) * warnings, all: Error and Warning Options. (line 61) * warnings, ampersand: Error and Warning Options. (line 87) * warnings, argument mismatch: Error and Warning Options. (line 125) * warnings, array temporaries: Error and Warning Options. (line 96) * warnings, character truncation: Error and Warning Options. (line 108) * warnings, conversion: Error and Warning Options. (line 117) * warnings, conversion <1>: Error and Warning Options. (line 121) * warnings, division of integers: Error and Warning Options. (line 150) * warnings, extra: Error and Warning Options. (line 131) * warnings, function elimination: Error and Warning Options. (line 246) * warnings, implicit interface: Error and Warning Options. (line 140) * warnings, implicit procedure: Error and Warning Options. (line 146) * warnings, integer division: Error and Warning Options. (line 150) * warnings, intrinsic: Error and Warning Options. (line 218) * warnings, intrinsics of other standards: Error and Warning Options. (line 154) * warnings, line truncation: Error and Warning Options. (line 111) * warnings, loop interchange: Error and Warning Options. (line 136) * warnings, nonstandard intrinsics: Error and Warning Options. (line 154) * warnings, overwrite recursive: Error and Warning Options. (line 161) * warnings, q exponent-letter: Error and Warning Options. (line 168) * warnings, suppressing: Error and Warning Options. (line 6) * warnings, suspicious code: Error and Warning Options. (line 172) * warnings, tabs: Error and Warning Options. (line 201) * warnings, to errors: Error and Warning Options. (line 292) * warnings, undefined do loop: Error and Warning Options. (line 209) * warnings, underflow: Error and Warning Options. (line 214) * warnings, unused dummy argument: Error and Warning Options. (line 229) * warnings, unused parameter: Error and Warning Options. (line 233) * warnings, use statements: Error and Warning Options. (line 225) * write character, stream mode: FPUT. (line 6) * write character, stream mode <1>: FPUTC. (line 6) * XOR: XOR. (line 6) * XOR reduction: PARITY. (line 6) * ZABS: ABS. (line 6) * ZCOS: COS. (line 6) * ZCOSD: COSD. (line 6) * zero bits: LEADZ. (line 6) * zero bits <1>: TRAILZ. (line 6) * ZEXP: EXP. (line 6) * ZLOG: LOG. (line 6) * ZSIN: SIN. (line 6) * ZSIND: SIND. (line 6) * ZSQRT: SQRT. (line 6)  Tag Table: Node: Top1954 Node: Introduction3286 Node: About GNU Fortran3633 Node: GNU Fortran and GCC8743 Node: Standards10944 Node: Fortran 95 status12387 Node: Fortran 2003 status13369 Node: Fortran 2008 status13819 Node: Fortran 2018 status14493 Node: Invoking GNU Fortran16194 Node: Option Summary18128 Node: Fortran Dialect Options22531 Ref: -funsigned40678 Node: Preprocessing Options40727 Node: Error and Warning Options51011 Node: Debugging Options64123 Node: Directory Options67958 Node: Link Options69469 Node: Runtime Options70628 Node: Developer Options72976 Node: Code Gen Options75440 Node: Interoperability Options98956 Node: Environment Variables101094 Node: Runtime101719 Node: TMPDIR102894 Node: GFORTRAN_STDIN_UNIT103596 Node: GFORTRAN_STDOUT_UNIT103982 Node: GFORTRAN_STDERR_UNIT104387 Node: GFORTRAN_UNBUFFERED_ALL104793 Node: GFORTRAN_UNBUFFERED_PRECONNECTED105348 Node: GFORTRAN_SHOW_LOCUS106020 Node: GFORTRAN_OPTIONAL_PLUS106544 Node: GFORTRAN_LIST_SEPARATOR107050 Node: GFORTRAN_CONVERT_UNIT107663 Node: GFORTRAN_ERROR_BACKTRACE111074 Node: GFORTRAN_FORMATTED_BUFFER_SIZE111706 Node: GFORTRAN_UNFORMATTED_BUFFER_SIZE112162 Node: Compiler Characteristics112599 Node: KIND Type Parameters113397 Node: Internal representation of LOGICAL variables114956 Node: Evaluation of logical expressions115861 Node: MAX and MIN intrinsics with REAL NaN arguments116720 Node: Thread-safety of the runtime library117597 Node: Data consistency and durability120082 Node: Files opened without an explicit ACTION= specifier123239 Node: File operations on symbolic links123958 Node: File format of unformatted sequential files125093 Node: Asynchronous I/O127487 Node: Behavior on integer overflow128235 Node: Extensions129019 Node: Extensions implemented in GNU Fortran129678 Node: Old-style kind specifications131650 Node: Old-style variable initialization132829 Node: Extensions to namelist134164 Node: X format descriptor without count field136709 Node: Commas in FORMAT specifications137248 Node: Missing period in FORMAT specifications138013 Node: Default widths for F/G/I format descriptors138612 Node: I/O item lists139324 Node: Q exponent-letter139725 Node: BOZ literal constants140350 Node: Real array indices142027 Node: Unary operators142330 Node: Implicitly convert LOGICAL and INTEGER values142744 Node: Hollerith constants support143767 Node: Character conversion146036 Node: Cray pointers146937 Node: CONVERT specifier152529 Node: OpenMP154939 Node: OpenACC157486 Node: Argument list functions158756 Node: Read/Write after EOF marker160451 Node: STRUCTURE and RECORD161070 Node: UNION and MAP166223 Node: Type variants for integer intrinsics169223 Node: AUTOMATIC and STATIC attributes171382 Node: Form feed as whitespace172969 Node: TYPE as an alias for PRINT173522 Node: %LOC as an rvalue174011 Node: .XOR. operator174678 Node: Bitwise logical operators175102 Node: Extended I/O specifiers176690 Node: Legacy PARAMETER statements180538 Node: Default exponents181169 Node: Extensions not implemented in GNU Fortran181533 Node: ENCODE and DECODE statements182558 Node: Variable FORMAT expressions183917 Node: Alternate complex function syntax185033 Node: Volatile COMMON blocks185597 Node: OPEN( ... 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and argument-passing conventions229009 Node: Naming conventions229728 Node: Argument passing conventions231268 Node: Coarray Programming236795 Node: Type and enum ABI Documentation237042 Node: caf_token_t237340 Node: caf_register_t237584 Node: caf_deregister_t238877 Node: caf_reference_t239411 Node: caf_team_t244147 Node: Function ABI Documentation244450 Node: _gfortran_caf_init247028 Node: _gfortran_caf_finish248487 Node: _gfortran_caf_this_image249441 Node: _gfortran_caf_num_images250218 Node: _gfortran_caf_image_status251348 Node: _gfortran_caf_failed_images252491 Node: _gfortran_caf_stopped_images253672 Node: _gfortran_caf_register254856 Node: _gfortran_caf_deregister259136 Node: _gfortran_caf_register_accessor260774 Node: _gfortran_caf_register_accessors_finish262967 Node: _gfortran_caf_get_remote_function_index264047 Node: _gfortran_caf_get_from_remote265869 Node: _gfortran_caf_is_present_on_remote270863 Node: _gfortran_caf_send_to_remote272648 Node: 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ACOSH346482 Node: ADJUSTL347602 Node: ADJUSTR348566 Node: AIMAG349539 Node: AINT351075 Node: ALARM352713 Node: ALL354398 Node: ALLOCATED356372 Node: AND357538 Node: ANINT359316 Node: ANY360854 Node: ASIN362834 Node: ASIND364162 Node: ASINH365398 Node: ASSOCIATED366528 Node: ATAN369569 Node: ATAND371099 Node: ATAN2372418 Node: ATAN2D374329 Node: ATANH376258 Node: ATOMIC_ADD377388 Node: ATOMIC_AND378967 Node: ATOMIC_CAS380600 Node: ATOMIC_DEFINE382503 Node: ATOMIC_FETCH_ADD384276 Node: ATOMIC_FETCH_AND386127 Node: ATOMIC_FETCH_OR387962 Node: ATOMIC_FETCH_XOR389784 Node: ATOMIC_OR391612 Node: ATOMIC_REF393242 Node: ATOMIC_XOR395192 Node: BACKTRACE396822 Node: BESSEL_J0397424 Node: BESSEL_J1398563 Node: BESSEL_JN399703 Node: BESSEL_Y0401679 Node: BESSEL_Y1402757 Node: BESSEL_YN403835 Node: BGE405822 Node: BGT406711 Node: BIT_SIZE407557 Node: BLE408500 Node: BLT409379 Node: BTEST410213 Node: C_ASSOCIATED411829 Node: C_F_POINTER413049 Node: C_F_PROCPOINTER414523 Node: C_FUNLOC416061 Node: 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FDATE489837 Node: FGET491353 Node: FGETC493220 Node: FINDLOC495074 Node: FLOOR497762 Node: FLUSH498788 Node: FNUM500706 Node: FPUT501457 Node: FPUTC503131 Node: FRACTION504956 Node: FREE505890 Node: FSEEK506763 Node: FSTAT509119 Node: FTELL510254 Node: GAMMA511258 Node: GERROR512372 Node: GETARG513143 Node: GET_COMMAND514900 Node: GET_COMMAND_ARGUMENT516301 Node: GETCWD518378 Node: GETENV519376 Node: GET_ENVIRONMENT_VARIABLE520829 Node: GETGID523029 Node: GETLOG523593 Node: GETPID524473 Node: GETUID525226 Node: GMTIME525769 Node: HOSTNM527574 Node: HUGE528517 Node: HYPOT529361 Node: IACHAR530205 Node: IALL531418 Node: IAND533041 Node: IANY535020 Node: IARGC536652 Node: IBCLR537704 Node: IBITS539068 Node: IBSET540691 Node: ICHAR542050 Node: IDATE544328 Node: IEOR545646 Node: IERRNO547518 Node: IMAGE_INDEX548084 Node: INDEX intrinsic549120 Node: INT550795 Node: INT2552942 Node: INT8553686 Node: IOR554430 Node: IPARITY556293 Node: IRAND557986 Node: IS_CONTIGUOUS559379 Node: IS_IOSTAT_END560570 Node: IS_IOSTAT_EOR561721 Node: ISATTY562894 Node: ISHFT563698 Node: ISHFTC565358 Node: ISNAN567273 Node: ITIME568071 Node: KILL569387 Node: KIND570539 Node: LBOUND571475 Node: LCOBOUND572841 Node: LEADZ574004 Node: LEN574910 Node: LEN_TRIM576289 Node: LGE577313 Node: LGT579000 Node: LINK580652 Node: LLE581730 Node: LLT583404 Node: LNBLNK585049 Node: LOC585858 Node: LOG586612 Node: LOG10588138 Node: LOG_GAMMA589166 Node: LOGICAL590422 Node: LSHIFT591272 Node: LSTAT592442 Node: LTIME593709 Node: MALLOC595436 Node: MASKL596944 Node: MASKR597737 Node: MATMUL598533 Node: MAX600007 Node: MAXEXPONENT601574 Node: MAXLOC602417 Node: MAXVAL605198 Node: MCLOCK607072 Node: MCLOCK8608140 Node: MERGE609423 Node: MERGE_BITS610197 Node: MIN611337 Node: MINEXPONENT612906 Node: MINLOC613567 Node: MINVAL616350 Node: MOD618141 Node: MODULO620615 Node: MOVE_ALLOC622317 Node: MVBITS623376 Node: NEAREST625189 Node: NEW_LINE626347 Node: NINT627138 Node: NORM2628602 Node: NOT629759 Node: NULL631067 Node: NUM_IMAGES631985 Node: OR633703 Node: OUT_OF_RANGE635477 Node: PACK637918 Node: PARITY639998 Node: PERROR641245 Node: POPCNT641892 Node: POPPAR642800 Node: PRECISION643898 Node: PRESENT644866 Node: PRODUCT645996 Node: RADIX647647 Node: RAN648485 Node: RAND648958 Node: RANDOM_INIT650330 Node: RANDOM_NUMBER652504 Node: RANDOM_SEED654028 Node: RANGE656561 Node: RANK657381 Node: REAL658180 Node: RENAME660515 Node: REPEAT661571 Node: RESHAPE662321 Node: RRSPACING663806 Node: RSHIFT664521 Node: SAME_TYPE_AS665743 Node: SCALE666585 Node: SCAN667396 Node: SECNDS668997 Node: SECOND670111 Node: SELECTED_CHAR_KIND671013 Node: SELECTED_INT_KIND672622 Node: SELECTED_LOGICAL_KIND673824 Node: SELECTED_REAL_KIND674946 Node: SELECTED_UNSIGNED_KIND677761 Node: SET_EXPONENT678870 Node: SHAPE679887 Node: SHIFTA681334 Node: SHIFTL682424 Node: SHIFTR683383 Node: SIGN684279 Node: SIGNAL685636 Node: SIN687662 Node: SIND688924 Node: SINH690207 Node: SIZE691194 Node: SIZEOF692540 Node: SLEEP694234 Node: SPACING694809 Node: SPREAD695837 Node: SQRT697006 Node: SRAND698329 Node: STAT699635 Node: STORAGE_SIZE702899 Node: SUM703796 Node: SYMLNK705405 Node: SYSTEM706587 Node: SYSTEM_CLOCK707880 Node: TAN710791 Node: TAND711911 Node: TANH712936 Node: THIS_IMAGE714149 Node: TIME716475 Node: TIME8717688 Node: TINY718937 Node: TRAILZ719564 Node: TRANSFER720427 Node: TRANSPOSE722489 Node: TRIM723201 Node: TTYNAM724080 Node: UBOUND725022 Node: UCOBOUND726440 Node: UINT727604 Node: UMASK728251 Node: UMASKL728955 Node: UMASKR729830 Node: UNLINK730707 Node: UNPACK731723 Node: VERIFY733045 Node: XOR734817 Node: Intrinsic Modules736670 Node: ISO_FORTRAN_ENV736957 Node: ISO_C_BINDING741838 Node: IEEE modules748095 Node: OpenMP Modules OMP_LIB and OMP_LIB_KINDS749279 Node: OpenACC Module OPENACC753891 Node: Contributing754853 Node: Contributors755683 Node: Projects757415 Node: Copying758593 Node: GNU Free Documentation License796159 Node: Funding821291 Node: Option Index823816 Node: Keyword Index843520  End Tag Table  Local Variables: coding: utf-8 End: