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Using GNU Fortran 13.0.0 (experimental 20221108) documentation
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Using GNU Fortran 13.0.0 (experimental 20221108) documentation
  • Copyright
  • Introduction
    • About GNU Fortran
    • GNU Fortran and GCC
    • Standards
  • GNU Fortran Command Options
    • Description
    • Option summary
    • Options controlling Fortran dialect
    • Enable and customize preprocessing
    • Options to request or suppress errors and warnings
    • Options for debugging your program or GNU Fortran
    • Options for directory search
    • Influencing the linking step
    • Influencing runtime behavior
    • Options for code generation conventions
    • Options for interoperability with other languages
    • Environment variables affecting gfortran
  • Runtime: Influencing runtime behavior with environment variables
    • 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 on all units
    • GFORTRAN_UNBUFFERED_PRECONNECTED—Do not buffer I/O on 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—Set buffer size for formatted I/O
    • GFORTRAN_UNFORMATTED_BUFFER_SIZE—Set buffer size for unformatted I/O
  • Compiler Characteristics
    • 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
  • Extensions
    • Extensions implemented in GNU Fortran
    • Extensions not implemented in GNU Fortran
  • Mixed-Language Programming
    • Interoperability with C
    • GNU Fortran Compiler Directives
    • Non-Fortran Main Program
    • Naming and argument-passing conventions
  • Coarray Programming
    • Type and enum ABI Documentation
    • Function ABI Documentation
  • Intrinsic Procedures
    • Introduction to intrinsic procedures
    • ABORT — Abort the program
    • ABS — Absolute value
    • ACCESS — Checks file access modes
    • ACHAR — Character in ASCII collating sequence
    • ACOS — Arccosine function
    • ACOSD — Arccosine function, degrees
    • ACOSH — Inverse hyperbolic cosine function
    • ADJUSTL — Left adjust a string
    • ADJUSTR — Right adjust a string
    • AIMAG — Imaginary part of complex number
    • AINT — Truncate to a whole number
    • ALARM — Execute a routine after a given delay
    • ALL — All values in MASK along DIM are true
    • ALLOCATED — Status of an allocatable entity
    • AND — Bitwise logical AND
    • ANINT — Nearest whole number
    • ANY — Any value in MASK along DIM is true
    • ASIN — Arcsine function
    • ASIND — Arcsine function, degrees
    • ASINH — Inverse hyperbolic sine function
    • ASSOCIATED — Status of a pointer or pointer/target pair
    • ATAN — Arctangent function
    • ATAND — Arctangent function, degrees
    • ATAN2 — Arctangent function
    • ATAN2D — Arctangent function, degrees
    • ATANH — Inverse hyperbolic tangent function
    • ATOMIC_ADD — Atomic ADD operation
    • ATOMIC_AND — Atomic bitwise AND operation
    • ATOMIC_CAS — Atomic compare and swap
    • ATOMIC_DEFINE — Setting a variable atomically
    • ATOMIC_FETCH_ADD — Atomic ADD operation with prior fetch
    • ATOMIC_FETCH_AND — Atomic bitwise AND operation with prior fetch
    • ATOMIC_FETCH_OR — Atomic bitwise OR operation with prior fetch
    • ATOMIC_FETCH_XOR — Atomic bitwise XOR operation with prior fetch
    • ATOMIC_OR — Atomic bitwise OR operation
    • ATOMIC_REF — Obtaining the value of a variable atomically
    • ATOMIC_XOR — Atomic bitwise OR operation
    • BACKTRACE — Show a backtrace
    • BESSEL_J0 — Bessel function of the first kind of order 0
    • BESSEL_J1 — Bessel function of the first kind of order 1
    • BESSEL_JN — Bessel function of the first kind
    • BESSEL_Y0 — Bessel function of the second kind of order 0
    • BESSEL_Y1 — Bessel function of the second kind of order 1
    • BESSEL_YN — Bessel function of the second kind
    • BGE — Bitwise greater than or equal to
    • BGT — Bitwise greater than
    • BIT_SIZE — Bit size inquiry function
    • BLE — Bitwise less than or equal to
    • BLT — Bitwise less than
    • BTEST — Bit test function
    • C_ASSOCIATED — Status of a C pointer
    • C_F_POINTER — Convert C into Fortran pointer
    • C_F_PROCPOINTER — Convert C into Fortran procedure pointer
    • C_FUNLOC — Obtain the C address of a procedure
    • C_LOC — Obtain the C address of an object
    • C_SIZEOF — Size in bytes of an expression
    • CEILING — Integer ceiling function
    • CHAR — Character conversion function
    • CHDIR — Change working directory
    • CHMOD — Change access permissions of files
    • CMPLX — Complex conversion function
    • CO_BROADCAST — Copy a value to all images the current set of images
    • CO_MAX — Maximal value on the current set of images
    • CO_MIN — Minimal value on the current set of images
    • CO_REDUCE — Reduction of values on the current set of images
    • CO_SUM — Sum of values on the current set of images
    • COMMAND_ARGUMENT_COUNT — Get number of command line arguments
    • COMPILER_OPTIONS — Options passed to the compiler
    • COMPILER_VERSION — Compiler version string
    • COMPLEX — Complex conversion function
    • CONJG — Complex conjugate function
    • COS — Cosine function
    • COSD — Cosine function, degrees
    • COSH — Hyperbolic cosine function
    • COTAN — Cotangent function
    • COTAND — Cotangent function, degrees
    • COUNT — Count function
    • CPU_TIME — CPU elapsed time in seconds
    • CSHIFT — Circular shift elements of an array
    • CTIME — Convert a time into a string
    • DATE_AND_TIME — Date and time subroutine
    • DBLE — Double conversion function
    • DCMPLX — Double complex conversion function
    • DIGITS — Significant binary digits function
    • DIM — Positive difference
    • DOT_PRODUCT — Dot product function
    • DPROD — Double product function
    • DREAL — Double real part function
    • DSHIFTL — Combined left shift
    • DSHIFTR — Combined right shift
    • DTIME — Execution time subroutine (or function)
    • EOSHIFT — End-off shift elements of an array
    • EPSILON — Epsilon function
    • ERF — Error function
    • ERFC — Error function
    • ERFC_SCALED — Error function
    • ETIME — Execution time subroutine (or function)
    • EVENT_QUERY — Query whether a coarray event has occurred
    • EXECUTE_COMMAND_LINE — Execute a shell command
    • EXIT — Exit the program with status.
    • EXP — Exponential function
    • EXPONENT — Exponent function
    • EXTENDS_TYPE_OF — Query dynamic type for extension
    • FDATE — Get the current time as a string
    • FGET — Read a single character in stream mode from stdin
    • FGETC — Read a single character in stream mode
    • FINDLOC — Search an array for a value
    • FLOOR — Integer floor function
    • FLUSH — Flush I/O unit(s)
    • FNUM — File number function
    • FPUT — Write a single character in stream mode to stdout
    • FPUTC — Write a single character in stream mode
    • FRACTION — Fractional part of the model representation
    • FREE — Frees memory
    • FSEEK — Low level file positioning subroutine
    • FSTAT — Get file status
    • FTELL — Current stream position
    • GAMMA — Gamma function
    • GERROR — Get last system error message
    • GETARG — Get command line arguments
    • GET_COMMAND — Get the entire command line
    • GET_COMMAND_ARGUMENT — Get command line arguments
    • GETCWD — Get current working directory
    • GETENV — Get an environmental variable
    • GET_ENVIRONMENT_VARIABLE — Get an environmental variable
    • GETGID — Group ID function
    • GETLOG — Get login name
    • GETPID — Process ID function
    • GETUID — User ID function
    • GMTIME — Convert time to GMT info
    • HOSTNM — Get system host name
    • HUGE — Largest number of a kind
    • HYPOT — Euclidean distance function
    • IACHAR — Code in ASCII collating sequence
    • IALL — Bitwise AND of array elements
    • IAND — Bitwise logical and
    • IANY — Bitwise OR of array elements
    • IARGC — Get the number of command line arguments
    • IBCLR — Clear bit
    • IBITS — Bit extraction
    • IBSET — Set bit
    • ICHAR — Character-to-integer conversion function
    • IDATE — Get current local time subroutine (day/month/year)
    • IEOR — Bitwise logical exclusive or
    • IERRNO — Get the last system error number
    • IMAGE_INDEX — Function that converts a cosubscript to an image index
    • INDEX — Position of a substring within a string
    • INT — Convert to integer type
    • INT2 — Convert to 16-bit integer type
    • INT8 — Convert to 64-bit integer type
    • IOR — Bitwise logical or
    • IPARITY — Bitwise XOR of array elements
    • IRAND — Integer pseudo-random number
    • IS_CONTIGUOUS — Test whether an array is contiguous
    • IS_IOSTAT_END — Test for end-of-file value
    • IS_IOSTAT_EOR — Test for end-of-record value
    • ISATTY — Whether a unit is a terminal device
    • ISHFT — Shift bits
    • ISHFTC — Shift bits circularly
    • ISNAN — Test for a NaN
    • ITIME — Get current local time subroutine (hour/minutes/seconds)
    • KILL — Send a signal to a process
    • KIND — Kind of an entity
    • LBOUND — Lower dimension bounds of an array
    • LCOBOUND — Lower codimension bounds of an array
    • LEADZ — Number of leading zero bits of an integer
    • LEN — Length of a character entity
    • LEN_TRIM — Length of a character entity without trailing blank characters
    • LGE — Lexical greater than or equal
    • LGT — Lexical greater than
    • LINK — Create a hard link
    • LLE — Lexical less than or equal
    • LLT — Lexical less than
    • LNBLNK — Index of the last non-blank character in a string
    • LOC — Returns the address of a variable
    • LOG — Natural logarithm function
    • LOG10 — Base 10 logarithm function
    • LOG_GAMMA — Logarithm of the Gamma function
    • LOGICAL — Convert to logical type
    • LSHIFT — Left shift bits
    • LSTAT — Get file status
    • LTIME — Convert time to local time info
    • MALLOC — Allocate dynamic memory
    • MASKL — Left justified mask
    • MASKR — Right justified mask
    • MATMUL — matrix multiplication
    • MAX — Maximum value of an argument list
    • MAXEXPONENT — Maximum exponent of a real kind
    • MAXLOC — Location of the maximum value within an array
    • MAXVAL — Maximum value of an array
    • MCLOCK — Time function
    • MCLOCK8 — Time function (64-bit)
    • MERGE — Merge variables
    • MERGE_BITS — Merge of bits under mask
    • MIN — Minimum value of an argument list
    • MINEXPONENT — Minimum exponent of a real kind
    • MINLOC — Location of the minimum value within an array
    • MINVAL — Minimum value of an array
    • MOD — Remainder function
    • MODULO — Modulo function
    • MOVE_ALLOC — Move allocation from one object to another
    • MVBITS — Move bits from one integer to another
    • NEAREST — Nearest representable number
    • NEW_LINE — New line character
    • NINT — Nearest whole number
    • NORM2 — Euclidean vector norms
    • NOT — Logical negation
    • NULL — Function that returns an disassociated pointer
    • NUM_IMAGES — Function that returns the number of images
    • OR — Bitwise logical OR
    • PACK — Pack an array into an array of rank one
    • PARITY — Reduction with exclusive OR
    • PERROR — Print system error message
    • POPCNT — Number of bits set
    • POPPAR — Parity of the number of bits set
    • PRECISION — Decimal precision of a real kind
    • PRESENT — Determine whether an optional dummy argument is specified
    • PRODUCT — Product of array elements
    • RADIX — Base of a model number
    • RAN — Real pseudo-random number
    • RAND — Real pseudo-random number
    • RANDOM_INIT — Initialize a pseudo-random number generator
    • RANDOM_NUMBER — Pseudo-random number
    • RANDOM_SEED — Initialize a pseudo-random number sequence
    • RANGE — Decimal exponent range
    • RANK — Rank of a data object
    • REAL — Convert to real type
    • RENAME — Rename a file
    • REPEAT — Repeated string concatenation
    • RESHAPE — Function to reshape an array
    • RRSPACING — Reciprocal of the relative spacing
    • RSHIFT — Right shift bits
    • SAME_TYPE_AS — Query dynamic types for equality
    • SCALE — Scale a real value
    • SCAN — Scan a string for the presence of a set of characters
    • SECNDS — Time function
    • SECOND — CPU time function
    • SELECTED_CHAR_KIND — Choose character kind
    • SELECTED_INT_KIND — Choose integer kind
    • SELECTED_REAL_KIND — Choose real kind
    • SET_EXPONENT — Set the exponent of the model
    • SHAPE — Determine the shape of an array
    • SHIFTA — Right shift with fill
    • SHIFTL — Left shift
    • SHIFTR — Right shift
    • SIGN — Sign copying function
    • SIGNAL — Signal handling subroutine (or function)
    • SIN — Sine function
    • SIND — Sine function, degrees
    • SINH — Hyperbolic sine function
    • SIZE — Determine the size of an array
    • SIZEOF — Size in bytes of an expression
    • SLEEP — Sleep for the specified number of seconds
    • SPACING — Smallest distance between two numbers of a given type
    • SPREAD — Add a dimension to an array
    • SQRT — Square-root function
    • SRAND — Reinitialize the random number generator
    • STAT — Get file status
    • STORAGE_SIZE — Storage size in bits
    • SUM — Sum of array elements
    • SYMLNK — Create a symbolic link
    • SYSTEM — Execute a shell command
    • SYSTEM_CLOCK — Time function
    • TAN — Tangent function
    • TAND — Tangent function, degrees
    • TANH — Hyperbolic tangent function
    • THIS_IMAGE — Function that returns the cosubscript index of this image
    • TIME — Time function
    • TIME8 — Time function (64-bit)
    • TINY — Smallest positive number of a real kind
    • TRAILZ — Number of trailing zero bits of an integer
    • TRANSFER — Transfer bit patterns
    • TRANSPOSE — Transpose an array of rank two
    • TRIM — Remove trailing blank characters of a string
    • TTYNAM — Get the name of a terminal device
    • UBOUND — Upper dimension bounds of an array
    • UCOBOUND — Upper codimension bounds of an array
    • UMASK — Set the file creation mask
    • UNLINK — Remove a file from the file system
    • UNPACK — Unpack an array of rank one into an array
    • VERIFY — Scan a string for characters not a given set
    • XOR — Bitwise logical exclusive OR
  • Intrinsic Modules
    • OpenACC Module OPENACC
    • ISO_FORTRAN_ENV
    • ISO_C_BINDING
    • IEEE modules: IEEE_EXCEPTIONS, IEEE_ARITHMETIC, and IEEE_FEATURES
    • OpenMP Modules OMP_LIB and OMP_LIB_KINDS
  • Contributing
    • Contributors to GNU Fortran
    • Projects
  • GNU GENERAL PUBLIC LICENSE
  • GNU Free Documentation License
  • Funding Free Software
  • Indexes and tables
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Introduction#

  • About GNU Fortran
  • GNU Fortran and GCC
  • Standards
    • Fortran 95 status
    • Fortran 2003 status
    • Fortran 2008 status
    • Fortran 2018 status
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Last updated on Nov 10, 2022