ABORT — Abort the program
ABS — Absolute value
ACHAR — Character in ASCII collating sequence
ACOS — Arc cosine function
ADJUSTL — Left adjust a string
ADJUSTR — Right adjust a string
AIMAG — Imaginary part of complex number
AINT — Imaginary part of complex number
ALARM — Execute a routine after a given delay
ALL — All values in MASK along DIM are true
ALLOCATED — Status of an allocatable entity
ANINT — Nearest whole number
ANY — Any value in MASK along DIM is true
ASIN — Arcsine function
ASSOCIATED — Status of a pointer or pointer/target pair
ATAN — Arctangent function
ATAN2 — Arctangent function
BESJ0 — Bessel function of the first kind of order 0
BESJ1 — Bessel function of the first kind of order 1
BESJN — Bessel function of the first kind
BESY0 — Bessel function of the second kind of order 0
BESY1 — Bessel function of the second kind of order 1
BESYN — Bessel function of the second kind
BIT_SIZE — Bit size inquiry function
BTEST — Bit test function
CEILING — Integer ceiling function
CHAR — Character conversion function
CMPLX — Complex conversion function
COMMAND_ARGUMENT_COUNT — Argument count function
CONJG — Complex conjugate function
COS — Cosine function
COSH — Hyperbolic cosine function
COUNT — Count function
CPU_TIME — CPU elapsed time in seconds
CSHIFT — Circular shift function
CTIME — Convert a time into a string
DATE_AND_TIME — Date and time subroutine
DBLE — Double conversion function
DCMPLX — Double complex conversion function
DFLOAT — Double conversion function
DIGITS — Significant digits function
DIM — Dim function
DOT_PRODUCT — Dot product function
DPROD — Double product function
DREAL — Double real part function
DTIME — Execution time subroutine (or function)
EOSHIFT — End-off shift function
EPSILON — Epsilon function
ERF — Error function
ERFC — Error function
ETIME — Execution time subroutine (or function)
EXIT — Exit the program with status.
EXP — Exponential function
EXPONENT — Exponent function
FDATE — Get the current time as a string
FLOAT — Convert integer to default real
FLOOR — Integer floor function
FLUSH — Flush I/O unit(s)
FNUM — File number function
FRACTION — Fractional part of the model representation
FREE — Frees memory
GETGID — Group ID function
GETPID — Process ID function
GETUID — User ID function
HUGE — Largest number of a kind
IACHAR — Code in ASCII collating sequence
ICHAR — Character-to-integer conversion function
IDATE — Get current local time subroutine (day/month/year)
IRAND — Integer pseudo-random number
ITIME — Get current local time subroutine (hour/minutes/seconds)
KIND — Kind of an entity
LOC — Returns the address of a variable
LOG — Logarithm function
LOG10 — Base 10 logarithm function
MALLOC — Allocate dynamic memory
MAXEXPONENT — Maximum exponent of a real kind
MINEXPONENT — Minimum exponent of a real kind
MOD — Remainder function
MODULO — Modulo function
NEAREST — Nearest representable number
NINT — Nearest whole number
PRECISION — Decimal precision of a real kind
RADIX — Base of a model number
RAND — Real pseudo-random number
RANGE — Decimal exponent range of a real kind
REAL — Convert to real type
RRSPACING — Reciprocal of the relative spacing
SCALE — Scale a real value
SELECTED_INT_KIND — Choose integer kind
SELECTED_REAL_KIND — Choose real kind
SECNDS — Time subroutine
SET_EXPONENT — Set the exponent of the model
SIGN — Sign copying function
SIGNAL — Signal handling subroutine (or function)
SIN — Sine function
SINH — Hyperbolic sine function
SNGL — Convert double precision real to default real
SQRT — Square-root function
SRAND — Reinitialize the random number generator
TAN — Tangent function
TANH — Hyperbolic tangent function
TINY — Smallest positive number of a real kind
This manual documents the use of gfortran, the GNU Fortran 95 compiler. You can find in this manual how to invoke gfortran, as well as its features and incompatibilities.
Gfortran is the GNU Fortran 95 compiler front end, designed initially as a free replacement for, or alternative to, the unix f95 command; gfortran is the command you'll use to invoke the compiler.
Gfortran is still in an early state of development. gfortran can generate code for most constructs and expressions, but much work remains to be done.
When gfortran is finished, it will do everything you expect from any decent compiler:
The compiler will also attempt to diagnose cases where the user's program contains a correct usage of the language, but instructs the computer to do something questionable. This kind of diagnostics message is called a warning message.
Gfortran consists of several components:
GCC used to be the GNU “C” Compiler, but is now known as the GNU Compiler Collection. GCC provides the GNU system with a very versatile compiler middle end (shared optimization passes), and back ends (code generators) for many different computer architectures and operating systems. The code of the middle end and back end are shared by all compiler front ends that are in the GNU Compiler Collection.
A GCC front end is essentially a source code parser and an intermediate code generator. The code generator translates the semantics of the source code into a language independent form called GENERIC.
The parser takes a source file written in a particular computer language, reads and parses it, and tries to make sure that the source code conforms to the language rules. Once the correctness of a program has been established, the compiler will build a data structure known as the Abstract Syntax tree, or just AST or “tree” for short. This data structure represents the whole program or a subroutine or a function. The “tree” is passed to the GCC middle end, which will perform optimization passes on it. The optimized AST is then handed off too the back end which assembles the program unit.
Different phases in this translation process can be, and in fact are merged in many compiler front ends. GNU Fortran 95 has a strict separation between the parser and code generator.
The goal of the gfortran project is to build a new front end for GCC. Specifically, a Fortran 95 front end. In a non-gfortran installation, gcc will not be able to compile Fortran 95 source code (only the “C” front end has to be compiled if you want to build GCC, all other languages are optional). If you build GCC with gfortran, gcc will recognize .f/.f90/.f95 source files and accepts Fortran 95 specific command line options.
Why do we write a compiler front end from scratch? There's a fine Fortran 77 compiler in the GNU Compiler Collection that accepts some features of the Fortran 90 standard as extensions. Why not start from there and revamp it?
One of the reasons is that Craig Burley, the author of G77, has decided to stop working on the G77 front end. On Craig explains the reasons for his decision to stop working on G77 in one of the pages in his homepage. Among the reasons is a lack of interest in improvements to g77. Users appear to be quite satisfied with g77 as it is. While g77 is still being maintained (by Toon Moene), it is unlikely that sufficient people will be willing to completely rewrite the existing code.
But there are other reasons to start from scratch. Many people, including Craig Burley, no longer agreed with certain design decisions in the G77 front end. Also, the interface of g77 to the back end is written in a style which is confusing and not up to date on recommended practice. In fact, a full rewrite had already been planned for GCC 3.0.
When Craig decided to stop, it just seemed to be a better idea to start a new project from scratch, because it was expected to be easier to maintain code we develop ourselves than to do a major overhaul of g77 first, and then build a Fortran 95 compiler out of it.
The gfortran command supports all the options supported by the gcc command. Only options specific to gfortran are documented here.
See GCC Command Options, for information on the non-Fortran-specific aspects of the gcc command (and, therefore, the gfortran command).
All gcc and gfortran 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 gfortran to the gcc distribution enables acceptance of gfortran 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.
Here is a summary of all the options specific to GNU Fortran, grouped by type. Explanations are in the following sections.
-ffree-form -fno-fixed-form
-fdollar-ok -fimplicit-none -fmax-identifier-length
-std=std -fd-lines-as-code -fd-lines-as-comments
-ffixed-line-length-n -ffixed-line-length-none
-ffree-line-length-n -ffree-line-length-none
-fdefault-double-8 -fdefault-integer-8 -fdefault-real-8
-fcray-pointer -frange-check
-fsyntax-only -pedantic -pedantic-errors
-w -Wall -Waliasing -Wampersand -Wconversion -Wimplicit-interface
-Wnonstd-intrinsics -Wsurprising -Wunderflow
-Wunused-labels -Wline-truncation -W
-fdump-parse-tree -ffpe-trap=list
-Idir -Mdir
-fconvert=conversion -frecord-marker=length
-fno-automatic -ff2c -fno-underscoring -fsecond-underscore
-fbounds-check -fmax-stack-var-size=n
-fpackderived -frepack-arrays -fshort-enums
The following options control the dialect of Fortran that the compiler accepts:
-ffree-form-ffixed-form-fd-lines-as-code-fd-lines-as-comments-fdefault-double-8-fdefault-integer-8-fdefault-real-8-fdollar-ok-fno-backslash-ffixed-line-length-nPopular values for n include 72 (the standard and the default), 80 (card image), and 132 (corresponds to “extended-source” options in some popular compilers). n may 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.
-ffree-line-length-n-fmax-identifier-length=n-fimplicit-none-fcray-pointer-frange-checka = EXP(1000).
With `-fno-range-check', no error will be given and the variable a
will be assigned the value +Infinity.
-std=stdWarnings are diagnostic messages that report constructions which are not inherently erroneous but which are risky or suggest there might have been an error.
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 warnings produced by GNU Fortran:
-fsyntax-only-pedanticValid FORTRAN 95 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 gfortran in this area are welcome.
This should be used in conjunction with -std=std.
-pedantic-errors-w-Wall-Waliasingintent(in) and a dummy argument with intent(out) in a call
with an explicit interface.
The following example will trigger 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-Wconversion-Wimplicit-interface-Wnonstd-intrinsic-WsurprisingThis currently produces a warning under the following circumstances:
-Wunderflow-Wunused-labels-Werror-WSee Options to Request or Suppress Warnings, for information on more options offered by the GBE shared by gfortran, gcc and other GNU compilers.
Some of these have no effect when compiling programs written in Fortran.
GNU Fortran has various special options that are used for debugging either your program or gfortran
-fdump-parse-tree-ffpe-trap=listsqrt(-1.0)), `zero' (division by
zero), `overflow' (overflow in a floating point operation),
`underflow' (underflow in a floating point operation),
`precision' (loss of precision during operation) and `denormal'
(operation produced a denormal denormal value).
See Options for Debugging Your Program or GCC, for more information on debugging options.
These options affect how gfortran 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.
-IdirINCLUDE 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.
See Options for Directory Search, for information on the -I option.
-Mdir-JdirUSE
statement.
The default is the current directory.
-J is an alias for -M to avoid conflicts with existing GCC options.
These options affect the runtime behavior of gfortran.
-fconvert=conversionThis 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=lengthoff_t is specified to be on that particular system.
Note that specifying length as 4 limits the record
length of unformatted files to 2 GB. This option does not
extend the maximum possible record length on systems where
off_t is a four_byte quantity.
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 which is not the default. You can figure out the other form by either removing no- or adding it.
-fno-automaticSAVE statement was 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.)
-ff2cThe 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 which were compiled with different
calling conventions will break at execution time.
Caution: This will break code which passes intrinsic functions
of type default REAL or COMPLEX as actual arguments, as
the library implementations use the -fno-f2c calling conventions.
-fno-underscoringWith -funderscoring in effect, gfortran appends one underscore to external names with no underscores. This is done to ensure compatibility with code produced by many UNIX Fortran compilers.
Caution: The default behavior of gfortran is incompatible with f2c and g77, please use the -ff2c option if you want object files compiled with gfortran 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-a-vis existing libraries, tools, and so on).
For example, with -funderscoring, and assuming other defaults like -fcase-lower and that `j()' and `max_count()' are external functions while `my_var' and `lvar' are local variables, a statement like
I = J() + MAX_COUNT (MY_VAR, LVAR)
is implemented as something akin to:
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 gfortran code with other languages.
Note that just because the names match does not mean that the interface implemented by gfortran for an external name matches the interface implemented by some other language for that same name. That is, getting code produced by gfortran 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 will conflict 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.
In future versions of gfortran we hope to improve naming and linking issues so that debugging always involves using the names as they appear in the source, even if the names as seen by the linker are mangled to prevent accidental linking between procedures with incompatible interfaces.
-fsecond-underscoreThis option has no effect if -fno-underscoring is in effect. It is implied by the -ff2c option.
Otherwise, with this option, 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.
-fbounds-checkIn the future this may also include other forms of checking, eg. checking substring references.
-fmax-stack-var-size=nThis option currently only affects local arrays declared with constant bounds, and may not apply to all character variables. Future versions of gfortran may improve this behavior.
The default value for n is 32768.
-fpackderived-frepack-arraysThis should result in faster accesses to the array. However it can introduce significant overhead to the function call, especially when the passed data is discontiguous.
-fshort-enumsINTEGER kind a given
enumerator set will fit in, and give all its enumerators this kind.
See Options for Code Generation Conventions, for information on more options offered by the GBE shared by gfortran gcc and other GNU compilers.
GNU Fortran 95 currently does not make use of any environment variables to control its operation above and beyond those that affect the operation of gcc.
See Environment Variables Affecting GCC, for information on environment variables.
See Runtime, for environment variables that affect the run-time behavior of gfortran programs.
As soon as gfortran can parse all of the statements correctly, it will be in the “larva” state. When we generate code, the “puppa” state. When gfortran is done, we'll see if it will be a beautiful butterfly, or just a big bug....–Andy Vaught, April 2000
The start of the GNU Fortran 95 project was announced on the GCC homepage in March 18, 2000 (even though Andy had already been working on it for a while, of course).
Gfortran is currently reaching the stage where is is able to compile real world programs. However it is still under development and has many rough edges.
Some intrinsic functions map directly to library functions, and in most cases the name of the library function used depends on the type of the arguments. For some intrinsics we generate inline code, and for others, such as sin, cos and sqrt, we rely on the backend to use special instructions in the floating point unit of the CPU if available, or to fall back to a call to libm if these are not available.
Implementation of some non-elemental intrinsic functions (eg. DOT_PRODUCT, AVERAGE) is not yet optimal. This is hard because we have to make decisions whether to use inline code (good for small arrays as no function call overhead occurs) or generate function calls (good for large arrays as it allows use of hand-optimized assembly routines, SIMD instructions, etc.)
The IO library is in a mostly usable state. Unformatted I/O for
REAL(KIND=10) variables is currently not recommended.
Array intrinsics mostly work.
Here's a list of proposed extensions for gfortran, in no particular order. Most of these are necessary to be fully compatible with existing Fortran compilers, but they are not part of the official J3 Fortran 95 standard.
Makefile info.
The behaviour of the gfortran can be influenced by environment variables.
Malformed environment variables are silently ignored.
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.
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.
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.
This environment variable controls where library output is sent. If the first letter is 'y', 'Y' or '1', standard error is used. If the first letter is 'n', 'N' or '0', standard output is used.
This environment variable controls where scratch files are created. Default is '/tmp'.
This environment variable controls wether all output is unbuffered. If the first letter is 'y', 'Y' or '1', all output is unbuffered. This will slow down large writes. If the first letter is 'n', 'N' or '0', output is bufferred. This is the default.
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', don't print filename and line numbers for runtime errors. The default is to print the location.
If the first letter is 'y', 'Y' or '1', a plus sign is printed where permitted by the Fortran standard. If the first lettter is 'n', 'N' or '0', a plus sign is not printed in most cases. Default is not to print plus signs.
This environment variable specifies the default record length for
files which are opened without a RECL tag in the OPEN
statement. This must be a positive integer. The default value is
1073741824.
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 gfortran program that you want to run.
Default is a single space.
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 is:
GFORTRAN_CONVERT_UNIT: mode | mode ';' 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.
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.
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.
See CONVERT specifier, for an alternative way to specify the
data representation for unformatted files. See Runtime Options, for
setting a default data representation for the whole program. The
CONVERT specifier overrides the -fconvert compile options.
gfortran implements a number of extensions over standard Fortran. This chapter contains information on their syntax and meaning. There are currently two categories of gfortran extensions, those that provide functionality beyond that provided by any standard, and those that are supported by gfortran 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 or -std=f2003 disables both types of extensions, and -std=legacy allows both without warning.
gfortran allows old-style kind specifications in declarations. These look like:
TYPESPEC*k x,y,z
where TYPESPEC is a basic type, and where k is a valid kind
number for that type. The statement then declares x, y
and z to be of type TYPESPEC with kind k. In
other words, it is equivalent to the standard conforming declaration
TYPESPEC(k) x,y,z
gfortran allows old-style initialization of variables of the form:
INTEGER*4 i/1/,j/2/
REAL*8 x(2,2) /3*0.,1./
These are only allowed in declarations without double colons
(::), as these were introduced in Fortran 90 which also
introduced a new syntax for variable initializations. The syntax for
the individual initializers is as for the DATA statement, but
unlike in a DATA statement, an initializer only applies to the
variable immediately preceding. In other words, something like
INTEGER I,J/2,3/ is not valid.
Examples of standard conforming code equivalent to the above example, are:
! Fortran 90
INTEGER(4) :: i = 1, j = 2
REAL(8) :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x))
! Fortran 77
INTEGER i, j
DOUBLE PRECISION x(2,2)
DATA i,j,x /1,2,3*0.,1./
gfortran 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. Two 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 noticed 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
To support legacy codes, gfortran 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)
To support legacy codes, gfortran allows the comma separator to be omitted immediately before and after character string edit descriptors in FORMAT statements.
PRINT 10, 2, 3
10 FORMAT ('FOO='I1' BAR='I2)
To support legacy codes, gfortran 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.
As a GNU extension, gfortran allows hexadecimal constants to be specified using the X prefix, in addition to the standard Z prefix.
As a GNU extension, gfortran allows arrays to be indexed using real types, whose values are implicitly converted to integers.
As a GNU extension, gfortran 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
As a GNU extension for backwards compatibility with other compilers,
gfortran allows the implicit conversion of LOGICALs to INTEGERs
and vice versa. When converting from a LOGICAL to an INTEGER, the numeric
value of .FALSE. is zero, and that of .TRUE. is one. When
converting from INTEGER to LOGICAL, the value zero is interpreted as
.FALSE. and any nonzero value is interpreted as .TRUE..
INTEGER*4 i
i = .FALSE.
A Hollerith constant is a string of characters preceded by the letter `H' or `h', and there must be an literal, unsigned, nonzero default integer constant indicating the number of characters in the string. Hollerith constants are stored as byte strings, one character per byte.
gfortran supports Hollerith constants. They can be used as the right
hands in the DATA statement and ASSIGN statement, also as the
arguments. The left hands can be of Integer, Real, Complex and Logical type.
The constant will be padded or truncated to fit the size of left hand.
Valid Hollerith constants examples:
complex*16 x(2)
data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/
call foo (4H abc)
x(1) = 16Habcdefghijklmnop
Invalid Hollerith constants examples:
integer*4 a
a = 8H12345678 ! The Hollerith constant is too long. It will be truncated.
a = 0H ! At least one character needed.
Cray pointers are part of a non-standard 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 ( <pointer> , <pointee> )
or,
pointer ( <pointer1> , <pointee1> ), ( <pointer2> , <pointee2> ), ...
The pointer is an integer that is intended to hold a memory address. The pointee may be an array or scalar. 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 – but 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 will issue 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 will ensure 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 one familiar with C pointer arithmetic might
expect. Adding 1 to ipt just adds one byte to the address stored in
ipt.
Any expression involving the pointee will be 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(), loc() is essentially the C '&' operator, 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 a malloc-type function. There is no malloc intrinsic implemented as part of the Cray pointer extension, but it might be a useful future addition to gfortran. Even without an intrinsic malloc function, dynamic memory allocation can be combined with Cray pointers by calling a short C function:
mymalloc.c:
void mymalloc_(void **ptr, int *nbytes)
{
*ptr = malloc(*nbytes);
return;
}
caller.f:
program caller
integer ipinfo;
real*4 data
pointer (ipdata, data(1024))
call mymalloc(ipdata,4*1024)
end
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, will 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 illegal. It is the user's responsibility to avoid doing this; the compiler works under the assumption that no such aliasing occurs.
Cray pointers will work correctly when there is no aliasing (i.e., when they're 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 illegal. (Note that this is not unique to gfortran; any Fortran compiler that supports Cray pointers will “incorrectly” optimize code with illegal aliasing.)
There are a number of restrictions on the attributes that can be applied to Cray pointers and pointees. Pointees may not have the attributes ALLOCATABLE, INTENT, OPTIONAL, DUMMY, TARGET, EXTERNAL, INTRINSIC, or POINTER. Pointers may not have the attributes DIMENSION, POINTER, TARGET, ALLOCATABLE, EXTERNAL, or INTRINSIC. 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 pointer may be modified during the course of a program, and this will change 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 will not change the base address of the array that was passed.
gfortran 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.
See GFORTRAN_CONVERT_UNIT, for an alternative way of specifying
the data format via an environment variable.
Valid values for CONVERT 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.
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 sytems of kinds 4 and 8. Conversion between different
“extended double” types on different architectures such as
m68k and x86_64, which gfortran
supports as REAL(KIND=10) will probably not work.
Note that the values specified via the GFORTRAN_CONVERT_UNIT environment variable will override the CONVERT specifier in the open statement. This is to give control over data formats to a user who does not have the source code of his 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.
This portion of the document is incomplete and undergoing massive expansion and editing. All contributions and corrections are strongly encouraged.
Gfortran provides a rich set of intrinsic procedures that includes all the intrinsic procedures required by the Fortran 95 standard, a set of intrinsic procedures for backwards compatibility with Gnu Fortran 77 (i.e., g77), and a small selection of intrinsic procedures from the Fortran 2003 standard. Any description here, which conflicts with a description in either the Fortran 95 standard or the Fortran 2003 standard, 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. Gfortran 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, which have 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
will be specified by KIND=*, and in the description of specific
names for an intrinsic procedure the kind type parameter will be explicitly
given (e.g., REAL(KIND=4) or REAL(KIND=8)). Finally, for
brevity the optional KIND= syntax will be omitted.
Many of the intrinsics 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.
Gfortran offers the -std=f95 and -std=gnu options, 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 option(s) is noted.
ABORT — Abort the programABORT causes immediate termination of the program. On operating
systems that support a core dump, ABORT will produce a core dump,
which is suitable for debugging purposes.
CALL ABORT
program test_abort
integer :: i = 1, j = 2
if (i /= j) call abort
end program test_abort
ABS — Absolute valueABS(X) computes the absolute value of X.
X = ABS(X)
| X | The type of the argument shall be an INTEGER(*),
REAL(*), or COMPLEX(*).
|
REAL(*) for a
COMPLEX(*) argument.
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
| Name | Argument | Return type | Option
|
CABS(Z) | COMPLEX(4) Z | REAL(4) | f95, gnu
|
DABS(X) | REAL(8) X | REAL(8) | f95, gnu
|
IABS(I) | INTEGER(4) I | INTEGER(4) | f95, gnu
|
ZABS(Z) | COMPLEX(8) Z | COMPLEX(8) | gnu
|
CDABS(Z) | COMPLEX(8) Z | COMPLEX(8) | gnu
|
ACHAR — Character in ASCII collating sequenceACHAR(I) returns the character located at position I
in the ASCII collating sequence.
C = ACHAR(I)
| I | The type shall be INTEGER(*).
|
CHARACTER with a length of one. The
kind type parameter is the same as KIND('A').
program test_achar
character c
c = achar(32)
end program test_achar
ACOS — Arc cosine functionACOS(X) computes the arc cosine of X.
X = ACOS(X)
| X | The type shall be REAL(*) with a magnitude that is
less than one.
|
REAL(*) and it lies in the
range 0 \leq \arccos (x) \leq \pi. The kind type
parameter is the same as X.
program test_acos
real(8) :: x = 0.866_8
x = achar(x)
end program test_acos
| Name | Argument | Return type | Option
|
DACOS(X) | REAL(8) X | REAL(8) | f95, gnu
|
ADJUSTL — Left adjust a stringADJUSTL(STR) will left adjust a string by removing leading spaces.
Spaces are inserted at the end of the string as needed.
STR = ADJUSTL(STR)
| STR | The type shall be CHARACTER.
|
CHARACTER where leading spaces
are removed and the same number of spaces are inserted on the end
of STR.
program test_adjustl
character(len=20) :: str = ' gfortran'
str = adjustl(str)
print *, str
end program test_adjustl
ADJUSTR — Right adjust a stringADJUSTR(STR) will right adjust a string by removing trailing spaces.
Spaces are inserted at the start of the string as needed.
STR = ADJUSTR(STR)
| STR | The type shall be CHARACTER.
|
CHARACTER where trailing spaces
are removed and the same number of spaces are inserted at the start
of STR.
program test_adjustr
character(len=20) :: str = 'gfortran'
str = adjustr(str)
print *, str
end program test_adjustr
AIMAG — Imaginary part of complex numberAIMAG(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.
X = AIMAG(Z)
| Z | The type of the argument shall be COMPLEX(*).
|
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
| Name | Argument | Return type | Option
|
DIMAG(Z) | COMPLEX(8) Z | REAL(8) | f95, gnu
|
IMAG(Z) | COMPLEX(*) Z | REAL(*) | gnu
|
IMAGPART(Z) | COMPLEX(*) Z | REAL(*) | gnu
|
AINT — Imaginary part of complex numberAINT(X [, KIND]) truncates its argument to a whole number.
X = AINT(X)
X = AINT(X, KIND)
| X | The type of the argument shall be REAL(*).
|
| KIND | (Optional) KIND shall be a scalar integer
initialization expression.
|
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.
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
| Name | Argument | Return type | Option
|
DINT(X) | REAL(8) X | REAL(8) | f95, gnu
|
ALARM — Execute a routine after a given delayALARM(SECONDS [, STATUS]) causes external subroutine HANDLER
to be executed after a delay of SECONDS by using alarm(1) to
set up a signal and signal(2) to catch it. If STATUS is
supplied, it will be 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.
CALL ALARM(SECONDS, HANDLER)
CALL ALARM(SECONDS, HANDLER, STATUS)
| 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.
INTEGER. It is INTENT(IN).
|
| STATUS | (Optional) STATUS shall be a scalar
INTEGER variable. It is INTENT(OUT).
|
program test_alarm
external handler_print
integer i
call alarm (3, handler_print, i)
print *, i
call sleep(10)
end program test_alarm
This will cause the external routine handler_print to be called after 3 seconds.
ALL — All values in MASK along DIM are trueALL(MASK [, DIM]) determines if all the values are true in MASK
in the array along dimension DIM.
L = ALL(MASK)
L = ALL(MASK, DIM)
| 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.
|
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.
ALL(MASK) is true if all elements of MASK are true.
It also is true if MASK has zero size; otherwise, it is false.
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.
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
ALLOCATED — Status of an allocatable entityALLOCATED(X) checks the status of whether X is allocated.
L = ALLOCATED(X)
| X | The argument shall be an ALLOCATABLE array.
|
LOGICAL with the default logical
kind type parameter. If X is allocated, ALLOCATED(X)
is .TRUE.; otherwise, it returns the .TRUE.
program test_allocated
integer :: i = 4
real(4), allocatable :: x(:)
if (allocated(x) .eqv. .false.) allocate(x(i)
end program test_allocated
ANINT — Nearest whole numberANINT(X [, KIND]) rounds its argument to the nearest whole number.
X = ANINT(X)
X = ANINT(X, KIND)
| X | The type of the argument shall be REAL(*).
|
| KIND | (Optional) KIND shall be a scalar integer
initialization expression.
|
ANINT(X) returns AINT(X+0.5). If X is
less than or equal to zero, then return AINT(X-0.5).
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
| Name | Argument | Return type | Option
|
DNINT(X) | REAL(8) X | REAL(8) | f95, gnu
|
ANY — Any value in MASK along DIM is trueANY(MASK [, DIM]) determines if any of the values in the logical array
MASK along dimension DIM are .TRUE..
L = ANY(MASK)
L = ANY(MASK, DIM)
| 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.
|
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.
ANY(MASK) is true if any element of MASK is true;
otherwise, it is false. It also is false if MASK has zero size.
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.
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
ASIN — Arcsine functionASIN(X) computes the arcsine of its X.
X = ASIN(X)
| X | The type shall be REAL(*), and a magnitude that is
less than one.
|
REAL(*) and it lies in the
range -\pi / 2 \leq \arccos (x) \leq \pi / 2. The kind type
parameter is the same as X.
program test_asin
real(8) :: x = 0.866_8
x = asin(x)
end program test_asin
| Name | Argument | Return type | Option
|
DASIN(X) | REAL(8) X | REAL(8) | f95, gnu
|
ASSOCIATED — Status of a pointer or pointer/target pairASSOCIATED(PTR [, TGT]) determines the status of the pointer PTR
or if PTR is associated with the target TGT.
L = ASSOCIATED(PTR)
L = ASSOCIATED(PTR [, TGT])
| PTR | PTR shall have the POINTER attribute and
it can be of any type.
|
| TGT | (Optional) TGT shall be a POINTER or
a TARGET. It must have the same type, kind type parameter, and
array rank as PTR.
|
ASSOCIATED(PTR) returns a scalar value of type LOGICAL(4).
There are several cases:
ASSOCIATED(PTR) 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
ATAN — Arctangent functionATAN(X) computes the arctangent of X.
X = ATAN(X)
| X | The type shall be REAL(*).
|
REAL(*) and it lies in the
range - \pi / 2 \leq \arcsin (x) \leq \pi / 2.
program test_atan
real(8) :: x = 2.866_8
x = atan(x)
end program test_atan
| Name | Argument | Return type | Option
|
DATAN(X) | REAL(8) X | REAL(8) | f95, gnu
|
ATAN2 — Arctangent functionATAN2(Y,X) computes the arctangent of the complex number X + i Y.
X = ATAN2(Y,X)
| 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.
|
program test_atan2
real(4) :: x = 1.e0_4, y = 0.5e0_4
x = atan2(y,x)
end program test_atan2
| Name | Argument | Return type | Option
|
DATAN2(X) | REAL(8) X | REAL(8) | f95, gnu
|
BESJ0 — Bessel function of the first kind of order 0BESJ0(X) computes the Bessel function of the first kind of order 0
of X.
X = BESJ0(X)
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*) and it lies in the
range - 0.4027... \leq Bessel (0,x) \leq 1.
program test_besj0
real(8) :: x = 0.0_8
x = besj0(x)
end program test_besj0
| Name | Argument | Return type | Option
|
DBESJ0(X) | REAL(8) X | REAL(8) | gnu
|
BESJ1 — Bessel function of the first kind of order 1BESJ1(X) computes the Bessel function of the first kind of order 1
of X.
X = BESJ1(X)
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*) and it lies in the
range - 0.5818... \leq Bessel (0,x) \leq 0.5818 .
program test_besj1
real(8) :: x = 1.0_8
x = besj1(x)
end program test_besj1
| Name | Argument | Return type | Option
|
DBESJ1(X) | REAL(8) X | REAL(8) | gnu
|
BESJN — Bessel function of the first kindBESJN(N, X) computes the Bessel function of the first kind of order
N of X.
Y = BESJN(N, X)
| N | The type shall be INTEGER(*), and it shall be scalar.
|
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*).
program test_besjn
real(8) :: x = 1.0_8
x = besjn(5,x)
end program test_besjn
| Name | Argument | Return type | Option
|
DBESJN(X) | INTEGER(*) N | REAL(8) | gnu
|
REAL(8) X |
|
BESY0 — Bessel function of the second kind of order 0BESY0(X) computes the Bessel function of the second kind of order 0
of X.
X = BESY0(X)
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*).
program test_besy0
real(8) :: x = 0.0_8
x = besy0(x)
end program test_besy0
| Name | Argument | Return type | Option
|
DBESY0(X) | REAL(8) X | REAL(8) | gnu
|
BESY1 — Bessel function of the second kind of order 1BESY1(X) computes the Bessel function of the second kind of order 1
of X.
X = BESY1(X)
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*).
program test_besy1
real(8) :: x = 1.0_8
x = besy1(x)
end program test_besy1
| Name | Argument | Return type | Option
|
DBESY1(X) | REAL(8) X | REAL(8) | gnu
|
BESYN — Bessel function of the second kindBESYN(N, X) computes the Bessel function of the second kind of order
N of X.
Y = BESYN(N, X)
| N | The type shall be INTEGER(*), and it shall be scalar.
|
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*).
program test_besyn
real(8) :: x = 1.0_8
x = besyn(5,x)
end program test_besyn
| Name | Argument | Return type | Option
|
DBESYN(N,X) | INTEGER(*) N | REAL(8) | gnu
|
REAL(8) X |
|
BIT_SIZE — Bit size inquiry functionBIT_SIZE(I) returns the number of bits (integer precision plus sign bit)
represented by the type of I.
I = BIT_SIZE(I)
| I | The type shall be INTEGER(*).
|
INTEGER(*)
program test_bit_size
integer :: i = 123
integer :: size
size = bit_size(i)
print *, size
end program test_bit_size
BTEST — Bit test functionBTEST(I,POS) returns logical .TRUE. if the bit at POS
in I is set.
I = BTEST(I,POS)
| I | The type shall be INTEGER(*).
|
| POS | The type shall be INTEGER(*).
|
LOGICAL
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
CEILING — Integer ceiling functionCEILING(X) returns the least integer greater than or equal to X.
I = CEILING(X[,KIND])
| X | The type shall be REAL(*).
|
| KIND | Optional scaler integer initialization expression.
|
INTEGER(KIND)
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
CHAR — Character conversion functionCHAR(I,[KIND]) returns the character represented by the integer I.
C = CHAR(I[,KIND])
| I | The type shall be INTEGER(*).
|
| KIND | Optional scaler integer initialization expression.
|
CHARACTER(1)
program test_char
integer :: i = 74
character(1) :: c
c = char(i)
print *, i, c ! returns 'J'
end program test_char
CMPLX — Complex conversion functionCMPLX(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.
C = CMPLX(X[,Y,KIND])
| X | The type may be INTEGER(*), REAL(*), or COMPLEX(*).
|
| Y | Optional, allowed if X is not COMPLEX(*). May be INTEGER(*) or REAL(*).
|
| KIND | Optional scaler integer initialization expression.
|
COMPLEX(*)
program test_cmplx
integer :: i = 42
real :: x = 3.14
complex :: z
z = cmplx(i, x)
print *, z, cmplx(x)
end program test_cmplx
COMMAND_ARGUMENT_COUNT — Argument count functionCOMMAND_ARGUMENT_COUNT() returns the number of arguments passed on the
command line when the containing program was invoked.
I = COMMAND_ARGUMENT_COUNT()
| None
|
INTEGER(4)
program test_command_argument_count
integer :: count
count = command_argument_count()
print *, count
end program test_command_argument_count
CONJG — Complex conjugate functionCONJG(Z) returns the conjugate of Z. If Z is (x, y)
then the result is (x, -y)
Z = CONJG(Z)
| Z | The type shall be COMPLEX(*).
|
COMPLEX(*).
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
| Name | Argument | Return type | Option
|
DCONJG(Z) | COMPLEX(8) Z | COMPLEX(8) | gnu
|
COS — Cosine functionCOS(X) computes the cosine of X.
X = COS(X)
| X | The type shall be REAL(*) or
COMPLEX(*).
|
program test_cos
real :: x = 0.0
x = cos(x)
end program test_cos
| Name | Argument | Return type | Option
|
DCOS(X) | REAL(8) X | REAL(8) | f95, gnu
|
CCOS(X) | COMPLEX(4) X | COMPLEX(4) | f95, gnu
|
ZCOS(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
CDCOS(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
COSH — Hyperbolic cosine functionCOSH(X) computes the hyperbolic cosine of X.
X = COSH(X)
| X | The type shall be REAL(*).
|
REAL(*) and it is positive
( \cosh (x) \geq 0 .
program test_cosh
real(8) :: x = 1.0_8
x = cosh(x)
end program test_cosh
| Name | Argument | Return type | Option
|
DCOSH(X) | REAL(8) X | REAL(8) | f95, gnu
|
COUNT — Count functionCOUNT(MASK[,DIM]) counts the number of .TRUE. elements of
MASK along the dimension of DIM. If DIM is omitted it is
taken to be 1. DIM is a scaler of type INTEGER in the
range of 1 /leq DIM /leq n) where n is the rank of MASK.
I = COUNT(MASK[,DIM])
| MASK | The type shall be LOGICAL.
|
| DIM | The type shall be INTEGER.
|
INTEGER with rank equal to that of
MASK.
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
CPU_TIME — CPU elapsed time in secondsREAL value representing the elapsed CPU time in seconds. This
is useful for testing segments of code to determine execution time.
CPU_TIME(X)
| X | The type shall be REAL with INTENT(OUT).
|
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
CSHIFT — Circular shift functionCSHIFT(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 scaler 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.
A = CSHIFT(A, SHIFT[,DIM])
| ARRAY | May be any type, not scaler.
|
| SHIFT | The type shall be INTEGER.
|
| DIM | The type shall be INTEGER.
|
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
CTIME — Convert a time into a stringCTIME(T,S) converts T, a system time value, such as returned
by TIME8(), to a string of the form `Sat Aug 19 18:13:14
1995', and returns that string into S.
If CTIME is invoked as a function, it can not be invoked as a
subroutine, and vice versa.
T is an INTENT(IN) INTEGER(KIND=8) variable.
S is an INTENT(OUT) CHARACTER variable.
CALL CTIME(T,S).
|
S = CTIME(T), (not recommended).
|
| S | The type shall be of type CHARACTER.
|
| T | The type shall be of type INTEGER(KIND=8).
|
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
DATE_AND_TIME — Date and time subroutineDATE_AND_TIME(DATE, TIME, ZONE, VALUES) gets the corresponding date and
time information from the real-time system clock. DATE is
INTENT(OUT) and has form ccyymmdd. TIME is INTENT(OUT) and
has form hhmmss.sss. ZONE is INTENT(OUT) and has 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:
VALUE(1): | The year
| |
VALUE(2): | The month
| |
VALUE(3): | The day of the month
| |
VAlUE(4): | Time difference with UTC in minutes
| |
VALUE(5): | The hour of the day
| |
VALUE(6): | The minutes of the hour
| |
VALUE(7): | The seconds of the minute
| |
VALUE(8): | The milliseconds of the second
|
CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])
| DATE | (Optional) The type shall be CHARACTER(8) or larger.
|
| TIME | (Optional) The type shall be CHARACTER(10) or larger.
|
| ZONE | (Optional) The type shall be CHARACTER(5) or larger.
|
| VALUES | (Optional) The type shall be INTEGER(8).
|
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
DBLE — Double conversion functionDBLE(X) Converts X to double precision real type.
DFLOAT is an alias for DBLE
X = DBLE(X)
X = DFLOAT(X)
| X | The type shall be INTEGER(*), REAL(*), or COMPLEX(*).
|
program test_dble
real :: x = 2.18
integer :: i = 5
complex :: z = (2.3,1.14)
print *, dble(x), dble(i), dfloat(z)
end program test_dble
DCMPLX — Double complex conversion functionDCMPLX(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.
C = DCMPLX(X)
C = DCMPLX(X,Y)
| X | The type may be INTEGER(*), REAL(*), or COMPLEX(*).
|
| Y | Optional if X is not COMPLEX(*). May be INTEGER(*) or REAL(*).
|
COMPLEX(8)
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
DFLOAT — Double conversion functionDFLOAT(X) Converts X to double precision real type.
DFLOAT is an alias for DBLE. See DBLE.
DIGITS — Significant digits functionDIGITS(X) returns the number of significant 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.
C = DIGITS(X)
| X | The type may be INTEGER(*) or REAL(*).
|
INTEGER.
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
DIM — Dim functionDIM(X,Y) returns the difference X-Y if the result is positive;
otherwise returns zero.
X = DIM(X,Y)
| X | The type shall be INTEGER(*) or REAL(*)
|
| Y | The type shall be the same type and kind as X.
|
INTEGER(*) or REAL(*).
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
| Name | Argument | Return type | Option
|
IDIM(X,Y) | INTEGER(4) X,Y | INTEGER(4) | gnu
|
DDIM(X,Y) | REAL(8) X,Y | REAL(8) | gnu
|
DOT_PRODUCT — Dot product functionDOT_PRODUCT(X,Y) computes the dot product multiplication of two vectors
X and Y. 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(*) or REAL(*), the result is SUM(X*Y). If the
vectors are COMPLEX(*), the result is SUM(CONJG(X)*Y). If the
vectors are LOGICAL, the result is ANY(X.AND.Y).
S = DOT_PRODUCT(X,Y)
| X | The type shall be numeric or LOGICAL, rank 1.
|
| Y | The type shall be numeric or LOGICAL, rank 1.
|
INTEGER(*), REAL(*), or COMPLEX(*). If the arguments are
LOGICAL, the return value is .TRUE. or .FALSE..
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
DPROD — Double product functionDPROD(X,Y) returns the product X*Y.
D = DPROD(X,Y)
| X | The type shall be REAL.
|
| Y | The type shall be REAL.
|
REAL(8).
program test_dprod
integer :: i
real :: x = 5.2
real :: y = 2.3
real(8) :: d
d = dprod(x,y)
print *, d
end program test_dprod
DREAL — Double real part functionDREAL(Z) returns the real part of complex variable Z.
D = DREAL(Z)
| Z | The type shall be COMPLEX(8).
|
REAL(8).
program test_dreal
complex(8) :: z = (1.3_8,7.2_8)
print *, dreal(z)
end program test_dreal
DTIME — Execution time subroutine (or function)DTIME(TARRAY, RESULT) initially returns the number of seconds of runtime
since the start of the process's execution in RESULT. TARRAY
returns the user and system components of this time in TARRAY(1) and
TARRAY(2) respectively. RESULT is equal to TARRAY(1) +
TARRAY(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 (wraparounds) 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.
If DTIME is invoked as a function, it can not be invoked as a
subroutine, and vice versa.
TARRAY and RESULT are INTENT(OUT) and provide the following:
TARRAY(1): | User time in seconds.
| |
TARRAY(2): | System time in seconds.
| |
RESULT: | Run time since start in seconds.
|
CALL DTIME(TARRAY, RESULT).
|
RESULT = DTIME(TARRAY), (not recommended).
|
| TARRAY | The type shall be REAL, DIMENSION(2).
|
| RESULT | The type shall be REAL.
|
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
EOSHIFT — End-off shift functionEOSHIFT(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 scaler 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 Type | Boundary Value
|
| Numeric | 0 of the type and kind of ARRAY.
|
| Logical | .FALSE..
|
| Character(len) | len blanks.
|
A = EOSHIFT(A, SHIFT[,BOUNDARY, DIM])
| ARRAY | May be any type, not scaler.
|
| SHIFT | The type shall be INTEGER.
|
| BOUNDARY | Same type as ARRAY.
|
| DIM | The type shall be INTEGER.
|
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
EPSILON — Epsilon functionEPSILON(X) returns a nearly negligible number relative to 1.
C = EPSILON(X)
| X | The type shall be REAL(*).
|
program test_epsilon
real :: x = 3.143
real(8) :: y = 2.33
print *, EPSILON(x)
print *, EPSILON(y)
end program test_epsilon
ERF — Error functionERF(X) computes the error function of X.
X = ERF(X)
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*) and it is positive
( - 1 \leq erf (x) \leq 1 .
program test_erf
real(8) :: x = 0.17_8
x = erf(x)
end program test_erf
| Name | Argument | Return type | Option
|
DERF(X) | REAL(8) X | REAL(8) | gnu
|
ERFC — Error functionERFC(X) computes the complementary error function of X.
X = ERFC(X)
| X | The type shall be REAL(*), and it shall be scalar.
|
REAL(*) and it is positive
( 0 \leq erfc (x) \leq 2 .
program test_erfc
real(8) :: x = 0.17_8
x = erfc(x)
end program test_erfc
| Name | Argument | Return type | Option
|
DERFC(X) | REAL(8) X | REAL(8) | gnu
|
ETIME — Execution time subroutine (or function)ETIME(TARRAY, RESULT) returns the number of seconds of runtime
since the start of the process's execution in RESULT. TARRAY
returns the user and system components of this time in TARRAY(1) and
TARRAY(2) respectively. RESULT is equal to TARRAY(1) + TARRAY(2).
On some systems, the underlying timings are represented using types with sufficiently small limits that overflows (wraparounds) 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.
If ETIME is invoked as a function, it can not be invoked as a
subroutine, and vice versa.
TARRAY and RESULT are INTENT(OUT) and provide the following:
TARRAY(1): | User time in seconds.
| |
TARRAY(2): | System time in seconds.
| |
RESULT: | Run time since start in seconds.
|
CALL ETIME(TARRAY, RESULT).
|
RESULT = ETIME(TARRAY), (not recommended).
|
| TARRAY | The type shall be REAL, DIMENSION(2).
|
| RESULT | The type shall be REAL.
|
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
EXIT — Exit the program with status.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.
CALL EXIT([STATUS])
| STATUS | The type of the argument shall be INTEGER(*).
|
STATUS is passed to the parent process on exit.
program test_exit
integer :: STATUS = 0
print *, 'This program is going to exit.'
call EXIT(STATUS)
end program test_exit
EXP — Exponential functionEXP(X) computes the base e exponential of X.
X = EXP(X)
| X | The type shall be REAL(*) or
COMPLEX(*).
|
program test_exp
real :: x = 1.0
x = exp(x)
end program test_exp
| Name | Argument | Return type | Option
|
DEXP(X) | REAL(8) X | REAL(8) | f95, gnu
|
CEXP(X) | COMPLEX(4) X | COMPLEX(4) | f95, gnu
|
ZEXP(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
CDEXP(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
EXPONENT — Exponent functionEXPONENT(X) returns the value of the exponent part of X. If X
is zero the value returned is zero.
I = EXPONENT(X)
| X | The type shall be REAL(*).
|
INTEGER.
program test_exponent
real :: x = 1.0
integer :: i
i = exponent(x)
print *, i
print *, exponent(0.0)
end program test_exponent
FDATE — Get the current time as a stringFDATE(DATE) returns the current date (using the same format as
CTIME) in DATE. It is equivalent to CALL CTIME(DATE,
TIME8()).
If FDATE is invoked as a function, it can not be invoked as a
subroutine, and vice versa.
DATE is an INTENT(OUT) CHARACTER variable.
CALL FDATE(DATE).
|
DATE = FDATE(), (not recommended).
|
| DATE | The type shall be of type CHARACTER.
|
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
FLOAT — Convert integer to default realFLOAT(I) converts the integer I to a default real value.
X = FLOAT(I)
| I | The type shall be INTEGER(*).
|
REAL
program test_float
integer :: i = 1
if (float(i) /= 1.) call abort
end program test_float
FLOOR — Integer floor functionFLOOR(X) returns the greatest integer less than or equal to X.
I = FLOOR(X[,KIND])
| X | The type shall be REAL(*).
|
| KIND | Optional scaler integer initialization expression.
|
INTEGER(KIND)
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
FLUSH — Flush I/O unit(s)CALL FLUSH(UNIT)
| UNIT | (Optional) The type shall be INTEGER.
|
FLUSH
statement that should be prefered over the FLUSH intrinsic.
FNUM — File number functionFNUM(UNIT) returns the Posix file descriptor number corresponding to the
open Fortran I/O unit UNIT.
I = FNUM(UNIT)
| UNIT | The type shall be INTEGER.
|
INTEGER
program test_fnum
integer :: i
open (unit=10, status = "scratch")
i = fnum(10)
print *, i
close (10)
end program test_fnum
FRACTION — Fractional part of the model representationFRACTION(X) returns the fractional part of the model
representation of X.
Y = FRACTION(X)
| X | The type of the argument shall be a REAL.
|
X is returned;
it is X * RADIX(X)**(-EXPONENT(X)).
program test_fraction
real :: x
x = 178.1387e-4
print *, fraction(x), x * radix(x)**(-exponent(x))
end program test_fraction
FREE — Frees memoryMALLOC(). The FREE
intrinsic is an extension intended to be used with Cray pointers, and is
provided in gfortran to allow user to compile legacy code. For
new code using Fortran 95 pointers, the memory de-allocation intrinsic is
DEALLOCATE.
FREE(PTR)
| PTR | The type shall be INTEGER. It represents the
location of the memory that should be de-allocated.
|
MALLOC for an example.
GETGID — Group ID functionI = GETGID()
GETGID is an INTEGER of the default
kind.
GETPID for an example.
GETPID — Process ID functionI = GETPID()
GETPID is an INTEGER of the default
kind.
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
GETUID — User ID functionGETUID()
GETUID is an INTEGER of the default
kind.
GETPID for an example.
HUGE — Largest number of a kindHUGE(X) returns the largest number that is not an infinity in
the model of the type of X.
Y = HUGE(X)
| X | shall be of type REAL or INTEGER.
|
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
IACHAR — Code in ASCII collating sequenceIACHAR(C) returns the code for the ASCII character
in the first character position of C.
I = IACHAR(C)
| C | Shall be a scalar CHARACTER, with INTENT(IN)
|
INTEGER and of the default integer
kind.
program test_iachar
integer i
i = iachar(' ')
end program test_iachar
ICHAR — Character-to-integer conversion functionICHAR(C) returns the code for the character in the first character
position of C in the system's native character set.
The correspondence between character and their codes is not necessarily
the same between GNU Fortran implementations.
I = ICHAR(C)
| C | Shall be a scalar CHARACTER, with INTENT(IN)
|
INTEGER and of the default integer
kind.
program test_ichar
integer i
i = ichar(' ')
end program test_ichar
CHARACTER
value 154, returns an INTEGER or REAL value with the
value 154.
Instead, you can use internal-file I/O to do this kind of conversion. For example:
program read_val
integer value
character(len=10) string
string = '154'
read (string,'(I10)') value
print *, value
end program read_val
IDATE — Get current local time subroutine (day/month/year)IDATE(TARRAY) Fills TARRAY 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 TARRAY, respectively.
The year has four significant digits.
CALL IDATE(TARRAY)
| TARRAY | The type shall be INTEGER, DIMENSION(3) and
the kind shall be the default integer kind.
|
program test_idate
integer, dimension(3) :: tarray
call idate(tarray)
print *, tarray(1)
print *, tarray(2)
print *, tarray(3)
end program test_idate
IRAND — Integer pseudo-random numberIRAND(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.
I = IRAND(FLAG)
| FLAG | shall be a scalar INTEGER of kind 4.
|
INTEGER(kind=4) type.
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
ITIME — Get current local time subroutine (hour/minutes/seconds)IDATE(TARRAY) Fills TARRAY 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 TARRAY,
respectively.
CALL ITIME(TARRAY)
| TARRAY | The type shall be INTEGER, DIMENSION(3)
and the kind shall be the default integer kind.
|
program test_itime
integer, dimension(3) :: tarray
call itime(tarray)
print *, tarray(1)
print *, tarray(2)
print *, tarray(3)
end program test_itime
KIND — Kind of an entityKIND(X) returns the kind value of the entity X.
K = KIND(X)
| X | Shall be of type LOGICAL, INTEGER,
REAL, COMPLEX or CHARACTER.
|
INTEGER and of the default
integer kind.
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
LOC — Returns the address of a variableLOC(X) returns the address of X as an integer.
I = LOC(X)
| X | Variable of any type.
|
INTEGER(n), where n is the
size (in bytes) of a memory address on the target machine.
program test_loc
integer :: i
real :: r
i = loc(r)
print *, i
end program test_loc
LOG — Logarithm functionLOG(X) computes the logarithm of X.
X = LOG(X)
| X | The type shall be REAL(*) or
COMPLEX(*).
|
REAL(*) or COMPLEX(*).
The kind type parameter is the same as X.
program test_log
real(8) :: x = 1.0_8
complex :: z = (1.0, 2.0)
x = log(x)
z = log(z)
end program test_log
| Name | Argument | Return type | Option
|
ALOG(X) | REAL(4) X | REAL(4) | f95, gnu
|
DLOG(X) | REAL(8) X | REAL(8) | f95, gnu
|
CLOG(X) | COMPLEX(4) X | COMPLEX(4) | f95, gnu
|
ZLOG(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
CDLOG(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
LOG10 — Base 10 logarithm functionLOG10(X) computes the base 10 logarithm of X.
X = LOG10(X)
| X | The type shall be REAL(*) or
COMPLEX(*).
|
REAL(*) or COMPLEX(*).
The kind type parameter is the same as X.
program test_log10
real(8) :: x = 10.0_8
x = log10(x)
end program test_log10
| Name | Argument | Return type | Option
|
ALOG10(X) | REAL(4) X | REAL(4) | f95, gnu
|
DLOG10(X) | REAL(8) X | REAL(8) | f95, gnu
|
MALLOC — Allocate dynamic memoryMALLOC(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 gfortran to allow user to compile legacy code. For new code
using Fortran 95 pointers, the memory allocation intrinsic is
ALLOCATE.
PTR = MALLOC(SIZE)
| SIZE | The type shall be INTEGER(*).
|
INTEGER(K), with K such that
variables of type INTEGER(K) have the same size as
C pointers (sizeof(void *)).
MALLOC and
FREE with Cray pointers. This example is intended to run on
32-bit systems, where the default integer kind is suitable to store
pointers; on 64-bit systems, ptr_x would need to be declared as
integer(kind=8).
program test_malloc
integer i
integer ptr_x
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
MAXEXPONENT — Maximum exponent of a real kindMAXEXPONENT(X) returns the maximum exponent in the model of the
type of X.
I = MAXEXPONENT(X)
| X | shall be of type REAL.
|
INTEGER and of the default integer
kind.
program exponents
real(kind=4) :: x
real(kind=8) :: y
print *, minexponent(x), maxexponent(x)
print *, minexponent(y), maxexponent(y)
end program exponents
MINEXPONENT — Minimum exponent of a real kindMINEXPONENT(X) returns the minimum exponent in the model of the
type of X.
I = MINEXPONENT(X)
| X | shall be of type REAL.
|
INTEGER and of the default integer
kind.
MAXEXPONENT for an example.
MOD — Remainder functionMOD(A,P) computes the remainder of the division of A by P. It is
calculated as A - (INT(A/P) * P).
X = MOD(A,P)
| A | shall be a scalar of type INTEGER or REAL
|
| P | shall be a scalar of the same type as A and not
equal to zero
|
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
| Name | Arguments | Return type | Option
|
AMOD(A,P) | REAL(4) | REAL(4) | f95, gnu
|
DMOD(A,P) | REAL(8) | REAL(8) | f95, gnu
|
MODULO — Modulo functionMODULO(A,P) computes the A modulo P.
X = MODULO(A,P)
| A | shall be a scalar of type INTEGER or REAL
|
| P | shall be a scalar of the same type and kind as A
|
INTEGER: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).
REAL:MODULO(A,P) has the value of A - FLOOR (A / P) * P.
program test_mod
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 test_mod
| Name | Arguments | Return type | Option
|
AMOD(A,P) | REAL(4) | REAL(4) | f95, gnu
|
DMOD(A,P) | REAL(8) | REAL(8) | f95, gnu
|
NEAREST — Nearest representable numberNEAREST(X, S) returns the processor-representable number nearest
to X in the direction indicated by the sign of S.
Y = NEAREST(X, S)
| X | shall be of type REAL.
|
| S | (Optional) shall be of type REAL and
not equal to zero.
|
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.
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
NINT — Nearest whole numberNINT(X) rounds its argument to the nearest whole number.
X = NINT(X)
| X | The type of the argument shall be REAL.
|
INTEGER of the default kind.
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
| Name | Argument | Option
|
IDNINT(X) | REAL(8) | f95, gnu
|
PRECISION — Decimal precision of a real kindPRECISION(X) returns the decimal precision in the model of the
type of X.
I = PRECISION(X)
| X | shall be of type REAL or COMPLEX.
|
INTEGER and of the default integer
kind.
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
RADIX — Base of a model numberRADIX(X) returns the base of the model representing the entity X.
R = RADIX(X)
| X | Shall be of type INTEGER or REAL
|
INTEGER and of the default
integer kind.
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
RAND — Real pseudo-random numberRAND(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.
X = RAND(FLAG)
| FLAG | shall be a scalar INTEGER of kind 4.
|
REAL type and the default kind.
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
RAN intrinsic is
provided as an alias for RAND.
RANGE — Decimal exponent range of a real kindRANGE(X) returns the decimal exponent range in the model of the
type of X.
I = RANGE(X)
| X | shall be of type REAL or COMPLEX.
|
INTEGER and of the default integer
kind.
PRECISION for an example.
REAL — Convert to real typeREAL(X [, KIND]) converts its argument X to a real type. The
REALPART(X) function is provided for compatibility with g77,
and its use is strongly discouraged.
X = REAL(X)
|
X = REAL(X, KIND)
|
X = REALPART(Z)
|
| X | shall be INTEGER(*), REAL(*), or
COMPLEX(*).
|
| KIND | (Optional) KIND shall be a scalar integer.
|
REAL(*) variable or array under
the following rules:
REAL(X) is converted to a default real type if X is an
integer or real variable.
REAL(X) is converted to a real type with the kind type parameter
of X if X is a complex variable.
REAL(X, KIND) is converted to a real type with kind type
parameter KIND if X is a complex, integer, or real
variable.
program test_real
complex :: x = (1.0, 2.0)
print *, real(x), real(x,8), realpart(x)
end program test_real
RRSPACING — Reciprocal of the relative spacingRRSPACING(X) returns the reciprocal of the relative spacing of
model numbers near X.
Y = RRSPACING(X)
| X | shall be of type REAL.
|
ABS(FRACTION(X)) * FLOAT(RADIX(X))**DIGITS(X).
SCALE — Scale a real valueSCALE(X,I) returns X * RADIX(X)**I.
Y = SCALE(X, I)
| X | The type of the argument shall be a REAL.
|
| I | The type of the argument shall be a INTEGER.
|
X * RADIX(X)**I.
program test_scale
real :: x = 178.1387e-4
integer :: i = 5
print *, scale(x,i), x*radix(x)**i
end program test_scale
SELECTED_INT_KIND — Choose integer kindSELECTED_INT_KIND(I) return the kind value of the smallest integer
type that can represent all values ranging from -10^I (exclusive)
to 10^I (exclusive). If there is no integer kind that accomodates
this range, SELECTED_INT_KIND returns -1.
J = SELECTED_INT_KIND(I)
|
| I | shall be a scalar and of type INTEGER.
|
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
SELECTED_REAL_KIND — Choose real kindSELECTED_REAL_KIND(P,R) return the kind value of a real data type
with decimal precision greater of at least P digits and exponent
range greater at least R.
I = SELECTED_REAL_KIND(P,R)
|
| P | (Optional) shall be a scalar and of type INTEGER.
|
| R | (Optional) shall be a scalar and of type INTEGER.
|
SELECTED_REAL_KIND returns the value of the kind type parameter of
a real data type with decimal precision of at least P digits and a
decimal exponent range of at least R. 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
P
R
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
SECNDS — Time subroutineSECNDS(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.
T = SECNDS (X)
| Name | Type
|
| T | REAL(4)
|
| X | REAL(4)
|
program test_secnds
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
SET_EXPONENT — Set the exponent of the modelSET_EXPONENT(X, I) returns the real number whose fractional part
is that that of X and whose exponent part if I.
Y = SET_EXPONENT(X, I)
| X | shall be of type REAL.
|
| I | shall be of type INTEGER.
|
FRACTION(X) * RADIX(X)**I.
program test_setexp
real :: x = 178.1387e-4
integer :: i = 17
print *, set_exponent(x), fraction(x) * radix(x)**i
end program test_setexp
SIGN — Sign copying functionSIGN(A,B) returns the value of A with the sign of B.
X = SIGN(A,B)
| A | shall be a scalar of type INTEGER or REAL
|
| B | shall be a scalar of the same type and kind as A
|
ABS(A), else
it is -ABS(A).
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
| Name | Arguments | Return type | Option
|
ISIGN(A,P) | INTEGER(4) | INTEGER(4) | f95, gnu
|
DSIGN(A,P) | REAL(8) | REAL(8) | f95, gnu
|
SIGNAL — Signal handling subroutine (or function)SIGNAL(NUMBER, HANDLER [, STATUS]) causes external subroutine
HANDLER to be executed with a single integer argument 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).
CALL ALARM(NUMBER, HANDLER)
|
CALL ALARM(NUMBER, HANDLER, STATUS)
|
STATUS = ALARM(NUMBER, HANDLER)
|
| 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).
|
SIGNAL functions returns the value returned by signal(2).
program test_signal
intrinsic signal
external handler_print
call signal (12, handler_print)
call signal (10, 1)
call sleep (30)
end program test_signal
SIN — Sine functionSIN(X) computes the sine of X.
X = SIN(X)
| X | The type shall be REAL(*) or
COMPLEX(*).
|
program test_sin
real :: x = 0.0
x = sin(x)
end program test_sin
| Name | Argument | Return type | Option
|
DSIN(X) | REAL(8) X | REAL(8) | f95, gnu
|
CSIN(X) | COMPLEX(4) X | COMPLEX(4) | f95, gnu
|
ZSIN(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
CDSIN(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
SINH — Hyperbolic sine functionSINH(X) computes the hyperbolic sine of X.
X = SINH(X)
| X | The type shall be REAL(*).
|
REAL(*).
program test_sinh
real(8) :: x = - 1.0_8
x = sinh(x)
end program test_sinh
| Name | Argument | Return type | Option
|
DSINH(X) | REAL(8) X | REAL(8) | f95, gnu
|
SNGL — Convert double precision real to default realSNGL(A) converts the double precision real A
to a default real value. This is an archaic form of REAL
that is specific to one type for A.
X = SNGL(A)
| A | The type shall be a double precision REAL.
|
REAL.
SQRT — Square-root functionSQRT(X) computes the square root of X.
X = SQRT(X)
| X | The type shall be REAL(*) or
COMPLEX(*).
|
REAL(*) or COMPLEX(*).
The kind type parameter is the same as X.
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
| Name | Argument | Return type | Option
|
DSQRT(X) | REAL(8) X | REAL(8) | f95, gnu
|
CSQRT(X) | COMPLEX(4) X | COMPLEX(4) | f95, gnu
|
ZSQRT(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
CDSQRT(X) | COMPLEX(8) X | COMPLEX(8) | f95, gnu
|
SRAND — Reinitialize the random number generatorSRAND 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.
CALL SRAND(SEED)
| SEED | shall be a scalar INTEGER(kind=4).
|
RAND and IRAND for examples.
RANDOM_SEED to
initialize the pseudo-random numbers generator and RANDOM_NUMBER
to generate pseudo-random numbers. Please note that in
gfortran, 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 numbers generators.
TAN — Tangent functionTAN(X) computes the tangent of X.
X = TAN(X)
| X | The type shall be REAL(*).
|
REAL(*). The kind type parameter is
the same as X.
program test_tan
real(8) :: x = 0.165_8
x = tan(x)
end program test_tan
| Name | Argument | Return type | Option
|
DTAN(X) | REAL(8) X | REAL(8) | f95, gnu
|
TANH — Hyperbolic tangent functionTANH(X) computes the hyperbolic tangent of X.
X = TANH(X)
| X | The type shall be REAL(*).
|
REAL(*) and lies in the range
- 1 \leq tanh(x) \leq 1 .
program test_tanh
real(8) :: x = 2.1_8
x = tanh(x)
end program test_tanh
| Name | Argument | Return type | Option
|
DTANH(X) | REAL(8) X | REAL(8) | f95, gnu
|
TINY — Smallest positive number of a real kindTINY(X) returns the smallest positive (non zero) number
in the model of the type of X.
Y = TINY(X)
| X | shall be of type REAL.
|
HUGE for an example.
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 95, 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 gfortran, but others are “mainstream” projects in need of enthusiastic hackers. All of these projects are important! We'll eventually get around to the things here, but they are also things doable by someone who is willing and able.
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 gfortran project (in no particular order):
The following people have contributed bug reports, smaller or larger patches, and much needed feedback and encouragement for the gfortran project:
Many other individuals have helped debug, test and improve gfortran 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.
If you wish to work on the runtime libraries, please contact a project maintainer.
The GNU Fortran 95 Compiler aims to be a conforming implementation of ISO/IEC 1539:1997 (Fortran 95).
In the future it may also support other variants of and extensions to the Fortran language. These include ANSI Fortran 77, ISO Fortran 90, ISO Fortran 2003 and OpenMP.
Although gfortran focuses on implementing the Fortran 95 standard for the time being, a few Fortran 2003 features are currently available.
command_argument_count, get_command,
get_command_argument, and get_environment_variable.
[...] rather
than (/.../).
FLUSH statement.
IOMSG= specifier for I/O statements.
ENUM and ENUMERATOR statements. Interoperability with
gcc is guaranteed also for the case where the
-fshort-enums command line option is given.
Copyright © 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
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We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software.
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The precise terms and conditions for copying, distribution and modification follow.
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You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
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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, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items—whatever suits your program.
You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the program, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice
This 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 Library General Public License instead of this License.
Copyright © 2000,2001,2002 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
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.
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.
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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”.
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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.
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.
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.
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.
It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.
You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
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. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.
You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.
You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.
The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.
In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”
You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.
You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.
A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation's users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document's Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.
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.
You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
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 http://www.gnu.org/copyleft/.
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.
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 1.2
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.
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.
[...]: Fortran 2003 statusABORT: ABORTABS intrinsic: ABSACHAR intrinsic: ACHARACOS intrinsic: ACOSADJUSTL intrinsic: ADJUSTLADJUSTR intrinsic: ADJUSTRAIMAG intrinsic: AIMAGAINT intrinsic: AINTALARM intrinsic: ALARMALL intrinsic: ALLALLOCATED intrinsic: ALLOCATEDALOG intrinsic: LOGALOG10 intrinsic: LOG10AMOD intrinsic: MODANINT intrinsic: ANINTANY intrinsic: ANYASIN intrinsic: ASINASSOCIATED intrinsic: ASSOCIATEDATAN intrinsic: ATANATAN2 intrinsic: ATAN2BESJ0 intrinsic: BESJ0BESJ1 intrinsic: BESJ1BESJN intrinsic: BESJNBESY0 intrinsic: BESY0BESY1 intrinsic: BESY1BESYN intrinsic: BESYNBIT_SIZE intrinsic: BIT_SIZEBTEST intrinsic: BTESTCABS intrinsic: ABSCDABS intrinsic: ABSCDCOS intrinsic: COSCDEXP intrinsic: EXPCDLOG intrinsic: LOGCDSIN intrinsic: SINCDSQRT intrinsic: SQRTCEILING intrinsic: CEILINGCHAR intrinsic: CHARCLOG intrinsic: LOGCMPLX intrinsic: CMPLXCOMMAND_ARGUMENT_COUNT intrinsic: COMMAND_ARGUMENT_COUNTCONJG intrinsic: CONJGCOS intrinsic: COSCOSH intrinsic: COSHCOUNT intrinsic: COUNTCPU_TIME intrinsic: CPU_TIMECSHIFT intrinsic: CSHIFTCSQRT intrinsic: SQRTCTIME intrinsic: CTIMEDABS intrinsic: ABSDACOS intrinsic: ACOSDASIN intrinsic: ASINDATAN intrinsic: ATANDATAN2 intrinsic: ATAN2DATE_AND_TIME intrinsic: DATE_AND_TIMEDBESJ0 intrinsic: BESJ0DBESJ1 intrinsic: BESJ1DBESJN intrinsic: BESJNDBESY0 intrinsic: BESY0DBESY1 intrinsic: BESY1DBESYN intrinsic: BESYNDBLE intrinsic: DBLEDCMPLX intrinsic: DCMPLXDCONJG intrinsic: CONJGDCOS intrinsic: COSDCOSH intrinsic: COSHDDIM intrinsic: DIMDEXP intrinsic: EXPDFLOAT intrinsic: DFLOATDIGITS intrinsic: DIGITSDIM intrinsic: DIMDIMAG intrinsic: AIMAGDINT intrinsic: AINTDLOG intrinsic: LOGDLOG10 intrinsic: LOG10DMOD intrinsic: MODDNINT intrinsic: ANINTDOT_PRODUCT intrinsic: DOT_PRODUCTDPROD intrinsic: DPRODDREAL intrinsic: DREALDSIGN intrinsic: SIGNDSIN intrinsic: SINDSINH intrinsic: SINHDSQRT intrinsic: SQRTDTAN intrinsic: TANDTANH intrinsic: TANHDTIME intrinsic: DTIMEENUM statement: Fortran 2003 statusENUMERATOR statement: Fortran 2003 statusEOSHIFT intrinsic: EOSHIFTEPSILON intrinsic: EPSILONERF intrinsic: ERFERFC intrinsic: ERFCETIME intrinsic: ETIMEEXIT: EXITEXP intrinsic: EXPEXPONENT intrinsic: EXPONENTFDATE intrinsic: FDATEFLOAT intrinsic: FLOATFLOOR intrinsic: FLOORFLUSH: FLUSHFLUSH statement: Fortran 2003 statusFNUM intrinsic: FNUMFRACTION intrinsic: FRACTIONFREE intrinsic: FREEGETGID intrinsic: GETGIDGETPID intrinsic: GETPIDGETUID intrinsic: GETUIDHUGE intrinsic: HUGEIABS intrinsic: ABSIACHAR intrinsic: IACHARICHAR intrinsic: ICHARIDATE intrinsic: IDATEIDIM intrinsic: DIMIDNINT intrinsic: NINTIMAG intrinsic: AIMAGIMAGPART intrinsic: AIMAGIOMSG= specifier: Fortran 2003 statusIRAND intrinsic: IRANDISIGN intrinsic: SIGNITIME intrinsic: ITIMEKIND intrinsic: KINDLOC intrinsic: LOCLOG intrinsic: LOGLOG10 intrinsic: LOG10MALLOC intrinsic: MALLOCMAXEXPONENT intrinsic: MAXEXPONENTMINEXPONENT intrinsic: MINEXPONENTMOD intrinsic: MODMODULO intrinsic: MODULONEAREST intrinsic: NEARESTNINT intrinsic: NINTPRECISION intrinsic: PRECISIONRADIX intrinsic: RADIXRAN intrinsic: RANDRAND intrinsic: RANDRANGE intrinsic: RANGEREAL intrinsic: REALREALPART intrinsic: REALRRSPACING intrinsic: RRSPACINGSCALE intrinsic: SCALESECNDS intrinsic: SECNDSSELECTED_INT_KIND intrinsic: SELECTED_INT_KINDSELECTED_REAL_KIND intrinsic: SELECTED_REAL_KINDSET_EXPONENT intrinsic: SET_EXPONENTSIGN intrinsic: SIGNSIGNAL intrinsic: SIGNALSIN intrinsic: SINSINH intrinsic: SINHSNGL intrinsic: SNGLSQRT intrinsic: SQRTSRAND intrinsic: SRANDTAN intrinsic: TANTANH intrinsic: TANHTINY intrinsic: TINYZABS intrinsic: ABSZCOS intrinsic: COSZEXP intrinsic: EXPZLOG intrinsic: LOGZSIN intrinsic: SINZSQRT intrinsic: SQRT