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GFORTRAN(1)			      GNU			   GFORTRAN(1)

       gfortran - GNU Fortran compiler

       gfortran [-c|-S|-E]
		[-g] [-pg] [-Olevel]
		[-Wwarn...] [-pedantic]
		[-Idir...] [-Ldir...]
		[-Dmacro[=defn]...] [-Umacro]
		[-o outfile] infile...

       Only the most useful options are listed here; see below for the

       The gfortran command supports all the options supported by the gcc
       command.	 Only options specific to GNU Fortran are documented here.

       All GCC and GNU Fortran options are accepted both by gfortran and by
       gcc (as well as any other drivers built at the same time, such as g++),
       since adding GNU Fortran to the GCC distribution enables acceptance of
       GNU Fortran options by all of the relevant drivers.

       In some cases, options have positive and negative forms; the negative
       form of -ffoo would be -fno-foo.	 This manual documents only one of
       these two forms, whichever one is not the default.

       Here is a summary of all the options specific to GNU Fortran, grouped
       by type.	 Explanations are in the following sections.

       Fortran Language Options
	   -fall-intrinsics -fbackslash -fcray-pointer -fd-lines-as-code
	   -fd-lines-as-comments -fdefault-double-8 -fdefault-integer-8
	   -fdefault-real-8 -fdollar-ok -ffixed-line-length-n
	   -ffixed-line-length-none -ffree-form -ffree-line-length-n
	   -ffree-line-length-none -fimplicit-none -finteger-4-integer-8
	   -fmax-identifier-length -fmodule-private -fno-fixed-form
	   -fno-range-check -fopenmp -freal-4-real-10 -freal-4-real-16
	   -freal-4-real-8 -freal-8-real-10 -freal-8-real-16 -freal-8-real-4

       Preprocessing Options
	   -A-question[=answer] -Aquestion=answer -C -CC -Dmacro[=defn] -H -P
	   -Umacro -cpp -dD -dI -dM -dN -dU -fworking-directory -imultilib dir
	   -iprefix file -iquote -isysroot dir -isystem dir -nocpp -nostdinc

       Error and Warning Options
	   -Waliasing -Wall -Wampersand -Warray-bounds -Wc-binding-type
	   -Wcharacter-truncation -Wconversion -Wfunction-elimination
	   -Wimplicit-interface -Wimplicit-procedure -Wintrinsic-shadow
	   -Wintrinsics-std -Wline-truncation -Wno-align-commons -Wno-tabs
	   -Wreal-q-constant -Wsurprising -Wunderflow -Wunused-parameter
	   -Wrealloc-lhs Wrealloc-lhs-all -Wtarget-lifetime -fmax-errors=n
	   -fsyntax-only -pedantic -pedantic-errors

       Debugging Options
	   -fbacktrace -fdump-fortran-optimized -fdump-fortran-original
	   -fdump-parse-tree -ffpe-trap=list

       Directory Options
	   -Idir  -Jdir -fintrinsic-modules-path dir

       Link Options

       Runtime Options
	   -fconvert=conversion -fmax-subrecord-length=length
	   -frecord-marker=length -fsign-zero

       Code Generation Options
	   -faggressive-function-elimination -fblas-matmul-limit=n
	   -fbounds-check -fcheck-array-temporaries
	   -fcoarray=<none|single|lib> -fexternal-blas -ff2c
	   -ffrontend-optimize -finit-character=n -finit-integer=n
	   -finit-local-zero -finit-logical=<true|false>
	   -finit-real=<zero|inf|-inf|nan|snan> -fmax-array-constructor=n
	   -fmax-stack-var-size=n -fno-align-commons -fno-automatic
	   -fno-protect-parens -fno-underscoring -fno-whole-file
	   -fsecond-underscore -fpack-derived -frealloc-lhs -frecursive
	   -frepack-arrays -fshort-enums -fstack-arrays

   Options controlling Fortran dialect
       The following options control the details of the Fortran dialect
       accepted by the compiler:

	   Specify the layout used by the source file.	The free form layout
	   was introduced in Fortran 90.  Fixed form was traditionally used in
	   older Fortran programs.  When neither option is specified, the
	   source form is determined by the file extension.

	   This option causes all intrinsic procedures (including the GNU-
	   specific extensions) to be accepted.	 This can be useful with
	   -std=f95 to force standard-compliance but get access to the full
	   range of intrinsics available with gfortran.	 As a consequence,
	   -Wintrinsics-std will be ignored and no user-defined procedure with
	   the same name as any intrinsic will be called except when it is
	   explicitly declared "EXTERNAL".

	   Enable special treatment for lines beginning with "d" or "D" in
	   fixed form sources.	If the -fd-lines-as-code option is given they
	   are treated as if the first column contained a blank.  If the
	   -fd-lines-as-comments option is given, they are treated as comment

	   Set the "DOUBLE PRECISION" type to an 8 byte wide type.  If
	   -fdefault-real-8 is given, "DOUBLE PRECISION" would instead be
	   promoted to 16 bytes if possible, and -fdefault-double-8 can be
	   used to prevent this.  The kind of real constants like "1.d0" will
	   not be changed by -fdefault-real-8 though, so also
	   -fdefault-double-8 does not affect it.

	   Set the default integer and logical types to an 8 byte wide type.
	   Do nothing if this is already the default.  This option also
	   affects the kind of integer constants like 42.

	   Set the default real type to an 8 byte wide type.  Do nothing if
	   this is already the default.	 This option also affects the kind of
	   non-double real constants like 1.0, and does promote the default
	   width of "DOUBLE PRECISION" to 16 bytes if possible, unless
	   "-fdefault-double-8" is given, too.

	   Allow $ as a valid non-first character in a symbol name. Symbols
	   that start with $ are rejected since it is unclear which rules to
	   apply to implicit typing as different vendors implement different
	   rules.  Using $ in "IMPLICIT" statements is also rejected.

	   Change the interpretation of backslashes in string literals from a
	   single backslash character to "C-style" escape characters. The
	   following combinations are expanded "\a", "\b", "\f", "\n", "\r",
	   "\t", "\v", "\\", and "\0" to the ASCII characters alert,
	   backspace, form feed, newline, carriage return, horizontal tab,
	   vertical tab, backslash, and NUL, respectively.  Additionally,
	   "\x"nn, "\u"nnnn and "\U"nnnnnnnn (where each n is a hexadecimal
	   digit) are translated into the Unicode characters corresponding to
	   the specified code points. All other combinations of a character
	   preceded by \ are unexpanded.

	   Set the default accessibility of module entities to "PRIVATE".
	   Use-associated entities will not be accessible unless they are
	   explicitly declared as "PUBLIC".

	   Set column after which characters are ignored in typical fixed-form
	   lines in the source file, and through which spaces are assumed (as
	   if padded to that length) after the ends of short fixed-form lines.

	   Popular values for n include 72 (the standard and the default), 80
	   (card image), and 132 (corresponding to "extended-source" options
	   in some popular compilers).	n may also be none, meaning that the
	   entire line is meaningful and that continued character constants
	   never have implicit spaces appended to them to fill out the line.
	   -ffixed-line-length-0 means the same thing as

	   Set column after which characters are ignored in typical free-form
	   lines in the source file. The default value is 132.	n may be none,
	   meaning that the entire line is meaningful.	-ffree-line-length-0
	   means the same thing as -ffree-line-length-none.

	   Specify the maximum allowed identifier length. Typical values are
	   31 (Fortran 95) and 63 (Fortran 2003 and Fortran 2008).

	   Specify that no implicit typing is allowed, unless overridden by
	   explicit "IMPLICIT" statements.  This is the equivalent of adding
	   "implicit none" to the start of every procedure.

	   Promote all "INTEGER(KIND=4)" entities to an "INTEGER(KIND=8)"
	   entities.  If "KIND=8" is unavailable, then an error will be
	   issued.  This option should be used with care and may not be
	   suitable for your codes.  Areas of possible concern include calls
	   to external procedures, alignment in "EQUIVALENCE" and/or "COMMON",
	   generic interfaces, BOZ literal constant conversion, and I/O.
	   Inspection of the intermediate representation of the translated
	   Fortran code, produced by -fdump-tree-original, is suggested.

	   Enable the Cray pointer extension, which provides C-like pointer

	   Enable the OpenMP extensions.  This includes OpenMP "!$omp"
	   directives in free form and "c$omp", *$omp and "!$omp" directives
	   in fixed form, "!$" conditional compilation sentinels in free form
	   and "c$", "*$" and "!$" sentinels in fixed form, and when linking
	   arranges for the OpenMP runtime library to be linked in.  The
	   option -fopenmp implies -frecursive.

	   Disable range checking on results of simplification of constant
	   expressions during compilation.  For example, GNU Fortran will give
	   an error at compile time when simplifying "a = 1. / 0".  With this
	   option, no error will be given and "a" will be assigned the value
	   "+Infinity".	 If an expression evaluates to a value outside of the
	   relevant range of ["-HUGE()":"HUGE()"], then the expression will be
	   replaced by "-Inf" or "+Inf" as appropriate.	 Similarly, "DATA
	   i/Z'FFFFFFFF'/" will result in an integer overflow on most systems,
	   but with -fno-range-check the value will "wrap around" and "i" will
	   be initialized to -1 instead.

	   Promote all "REAL(KIND=M)" entities to "REAL(KIND=N)" entities.  If
	   "REAL(KIND=N)" is unavailable, then an error will be issued.	 All
	   other real kind types are unaffected by this option.	 These options
	   should be used with care and may not be suitable for your codes.
	   Areas of possible concern include calls to external procedures,
	   alignment in "EQUIVALENCE" and/or "COMMON", generic interfaces, BOZ
	   literal constant conversion, and I/O.  Inspection of the
	   intermediate representation of the translated Fortran code,
	   produced by -fdump-tree-original, is suggested.

	   Specify the standard to which the program is expected to conform,
	   which may be one of f95, f2003, f2008, gnu, or legacy.  The default
	   value for std is gnu, which specifies a superset of the Fortran 95
	   standard that includes all of the extensions supported by GNU
	   Fortran, although warnings will be given for obsolete extensions
	   not recommended for use in new code.	 The legacy value is
	   equivalent but without the warnings for obsolete extensions, and
	   may be useful for old non-standard programs.	 The f95, f2003 and
	   f2008 values specify strict conformance to the Fortran 95, Fortran
	   2003 and Fortran 2008 standards, respectively; errors are given for
	   all extensions beyond the relevant language standard, and warnings
	   are given for the Fortran 77 features that are permitted but
	   obsolescent in later standards. -std=f2008ts allows the Fortran
	   2008 standard including the additions of the Technical
	   Specification (TS) 29113 on Further Interoperability of Fortran
	   with C.

   Enable and customize preprocessing
       Preprocessor related options. See section Preprocessing and conditional
       compilation for more detailed information on preprocessing in gfortran.

	   Enable preprocessing. The preprocessor is automatically invoked if
	   the file extension is .fpp, .FPP,  .F, .FOR, .FTN, .F90, .F95, .F03
	   or .F08. Use this option to manually enable preprocessing of any
	   kind of Fortran file.

	   To disable preprocessing of files with any of the above listed
	   extensions, use the negative form: -nocpp.

	   The preprocessor is run in traditional mode. Any restrictions of
	   the file-format, especially the limits on line length, apply for
	   preprocessed output as well, so it might be advisable to use the
	   -ffree-line-length-none or -ffixed-line-length-none options.

       -dM Instead of the normal output, generate a list of '#define'
	   directives for all the macros defined during the execution of the
	   preprocessor, including predefined macros. This gives you a way of
	   finding out what is predefined in your version of the preprocessor.
	   Assuming you have no file foo.f90, the command

		     touch foo.f90; gfortran -cpp -E -dM foo.f90

	   will show all the predefined macros.

       -dD Like -dM except in two respects: it does not include the predefined
	   macros, and it outputs both the "#define" directives and the result
	   of preprocessing. Both kinds of output go to the standard output

       -dN Like -dD, but emit only the macro names, not their expansions.

       -dU Like dD except that only macros that are expanded, or whose
	   definedness is tested in preprocessor directives, are output; the
	   output is delayed until the use or test of the macro; and '#undef'
	   directives are also output for macros tested but undefined at the

       -dI Output '#include' directives in addition to the result of

	   Enable generation of linemarkers in the preprocessor output that
	   will let the compiler know the current working directory at the
	   time of preprocessing. When this option is enabled, the
	   preprocessor will emit, after the initial linemarker, a second
	   linemarker with the current working directory followed by two
	   slashes. GCC will use this directory, when it is present in the
	   preprocessed input, as the directory emitted as the current working
	   directory in some debugging information formats.  This option is
	   implicitly enabled if debugging information is enabled, but this
	   can be inhibited with the negated form -fno-working-directory. If
	   the -P flag is present in the command line, this option has no
	   effect, since no "#line" directives are emitted whatsoever.

       -idirafter dir
	   Search dir for include files, but do it after all directories
	   specified with -I and the standard system directories have been
	   exhausted. dir is treated as a system include directory.  If dir
	   begins with "=", then the "=" will be replaced by the sysroot
	   prefix; see --sysroot and -isysroot.

       -imultilib dir
	   Use dir as a subdirectory of the directory containing target-
	   specific C++ headers.

       -iprefix prefix
	   Specify prefix as the prefix for subsequent -iwithprefix options.
	   If the prefix represents a directory, you should include the final

       -isysroot dir
	   This option is like the --sysroot option, but applies only to
	   header files. See the --sysroot option for more information.

       -iquote dir
	   Search dir only for header files requested with "#include "file"";
	   they are not searched for "#include <file>", before all directories
	   specified by -I and before the standard system directories. If dir
	   begins with "=", then the "=" will be replaced by the sysroot
	   prefix; see --sysroot and -isysroot.

       -isystem dir
	   Search dir for header files, after all directories specified by -I
	   but before the standard system directories. Mark it as a system
	   directory, so that it gets the same special treatment as is applied
	   to the standard system directories. If dir begins with "=", then
	   the "=" will be replaced by the sysroot prefix; see --sysroot and

	   Do not search the standard system directories for header files.
	   Only the directories you have specified with -I options (and the
	   directory of the current file, if appropriate) are searched.

	   Do not predefine any system-specific or GCC-specific macros.	 The
	   standard predefined macros remain defined.

	   Make an assertion with the predicate predicate and answer answer.
	   This form is preferred to the older form -A predicate(answer),
	   which is still supported, because it does not use shell special

	   Cancel an assertion with the predicate predicate and answer answer.

       -C  Do not discard comments. All comments are passed through to the
	   output file, except for comments in processed directives, which are
	   deleted along with the directive.

	   You should be prepared for side effects when using -C; it causes
	   the preprocessor to treat comments as tokens in their own right.
	   For example, comments appearing at the start of what would be a
	   directive line have the effect of turning that line into an
	   ordinary source line, since the first token on the line is no
	   longer a '#'.

	   Warning: this currently handles C-Style comments only. The
	   preprocessor does not yet recognize Fortran-style comments.

       -CC Do not discard comments, including during macro expansion. This is
	   like -C, except that comments contained within macros are also
	   passed through to the output file where the macro is expanded.

	   In addition to the side-effects of the -C option, the -CC option
	   causes all C++-style comments inside a macro to be converted to
	   C-style comments. This is to prevent later use of that macro from
	   inadvertently commenting out the remainder of the source line. The
	   -CC option is generally used to support lint comments.

	   Warning: this currently handles C- and C++-Style comments only. The
	   preprocessor does not yet recognize Fortran-style comments.

	   Predefine name as a macro, with definition 1.

	   The contents of definition are tokenized and processed as if they
	   appeared during translation phase three in a '#define' directive.
	   In particular, the definition will be truncated by embedded newline

	   If you are invoking the preprocessor from a shell or shell-like
	   program you may need to use the shell's quoting syntax to protect
	   characters such as spaces that have a meaning in the shell syntax.

	   If you wish to define a function-like macro on the command line,
	   write its argument list with surrounding parentheses before the
	   equals sign (if any). Parentheses are meaningful to most shells, so
	   you will need to quote the option. With sh and csh,
	   "-D'name(args...)=definition'" works.

	   -D and -U options are processed in the order they are given on the
	   command line. All -imacros file and -include file options are
	   processed after all -D and -U options.

       -H  Print the name of each header file used, in addition to other
	   normal activities. Each name is indented to show how deep in the
	   '#include' stack it is.

       -P  Inhibit generation of linemarkers in the output from the
	   preprocessor.  This might be useful when running the preprocessor
	   on something that is not C code, and will be sent to a program
	   which might be confused by the linemarkers.

	   Cancel any previous definition of name, either built in or provided
	   with a -D option.

   Options to request or suppress errors and warnings
       Errors are diagnostic messages that report that the GNU Fortran
       compiler cannot compile the relevant piece of source code.  The
       compiler will continue to process the program in an attempt to report
       further errors to aid in debugging, but will not produce any compiled

       Warnings are diagnostic messages that report constructions which are
       not inherently erroneous but which are risky or suggest there is likely
       to be a bug in the program.  Unless -Werror is specified, they do not
       prevent compilation of the program.

       You can request many specific warnings with options beginning -W, for
       example -Wimplicit to request warnings on implicit declarations.	 Each
       of these specific warning options also has a negative form beginning
       -Wno- to turn off warnings; for example, -Wno-implicit.	This manual
       lists only one of the two forms, whichever is not the default.

       These options control the amount and kinds of errors and warnings
       produced by GNU Fortran:

	   Limits the maximum number of error messages to n, at which point
	   GNU Fortran bails out rather than attempting to continue processing
	   the source code.  If n is 0, there is no limit on the number of
	   error messages produced.

	   Check the code for syntax errors, but do not actually compile it.
	   This will generate module files for each module present in the
	   code, but no other output file.

	   Issue warnings for uses of extensions to Fortran 95.	 -pedantic
	   also applies to C-language constructs where they occur in GNU
	   Fortran source files, such as use of \e in a character constant
	   within a directive like "#include".

	   Valid Fortran 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
	   GNU Fortran in this area are welcome.

	   This should be used in conjunction with -std=f95, -std=f2003 or

	   Like -pedantic, except that errors are produced rather than

	   Enables commonly used warning options pertaining to usage that we
	   recommend avoiding and that we believe are easy to avoid.  This
	   currently includes -Waliasing, -Wampersand, -Wconversion,
	   -Wsurprising, -Wc-binding-type, -Wintrinsics-std, -Wno-tabs,
	   -Wintrinsic-shadow, -Wline-truncation, -Wtarget-lifetime,
	   -Wreal-q-constant and -Wunused.

	   Warn about possible aliasing of dummy arguments. Specifically, it
	   warns if the same actual argument is associated with a dummy
	   argument with "INTENT(IN)" and a dummy argument with "INTENT(OUT)"
	   in a call with an explicit interface.

	   The following example will trigger the warning.

		       subroutine bar(a,b)
			 integer, intent(in) :: a
			 integer, intent(out) :: b
		       end subroutine
		     end interface
		     integer :: a

		     call bar(a,a)

	   Warn about missing ampersand in continued character constants. The
	   warning is given with -Wampersand, -pedantic, -std=f95, -std=f2003
	   and -std=f2008. Note: With no ampersand given in a continued
	   character constant, GNU Fortran assumes continuation at the first
	   non-comment, non-whitespace character after the ampersand that
	   initiated the continuation.

	   Warn about array temporaries generated by the compiler.  The
	   information generated by this warning is sometimes useful in
	   optimization, in order to avoid such temporaries.

	   Warn if the a variable might not be C interoperable.	 In
	   particular, warn if the variable has been declared using an
	   intrinsic type with default kind instead of using a kind parameter
	   defined for C interoperability in the intrinsic "ISO_C_Binding"
	   module.  This option is implied by -Wall.

	   Warn when a character assignment will truncate the assigned string.

	   Warn when a source code line will be truncated.  This option is
	   implied by -Wall.

	   Warn about implicit conversions that are likely to change the value
	   of the expression after conversion. Implied by -Wall.

	   Warn about implicit conversions between different types and kinds.

	   Enables some warning options for usages of language features which
	   may be problematic. This currently includes -Wcompare-reals and

	   Warn if a procedure is called without an explicit interface.	 Note
	   this only checks that an explicit interface is present.  It does
	   not check that the declared interfaces are consistent across
	   program units.

	   Warn if a procedure is called that has neither an explicit
	   interface nor has been declared as "EXTERNAL".

	   Warn if gfortran finds a procedure named like an intrinsic not
	   available in the currently selected standard (with -std) and treats
	   it as "EXTERNAL" procedure because of this.	-fall-intrinsics can
	   be used to never trigger this behavior and always link to the
	   intrinsic regardless of the selected standard.

	   Produce a warning if a real-literal-constant contains a "q"

	   Produce a warning when "suspicious" code constructs are
	   encountered.	 While technically legal these usually indicate that
	   an error has been made.

	   This currently produces a warning under the following

	   o   An INTEGER SELECT construct has a CASE that can never be
	       matched as its lower value is greater than its upper value.

	   o   A LOGICAL SELECT construct has three CASE statements.

	   o   A TRANSFER specifies a source that is shorter than the

	   o   The type of a function result is declared more than once with
	       the same type.  If -pedantic or standard-conforming mode is
	       enabled, this is an error.

	   o   A "CHARACTER" variable is declared with negative length.

	   By default, tabs are accepted as whitespace, but tabs are not
	   members of the Fortran Character Set.  For continuation lines, a
	   tab followed by a digit between 1 and 9 is supported.  -Wno-tabs
	   will cause a warning to be issued if a tab is encountered. Note,
	   -Wno-tabs is active for -pedantic, -std=f95, -std=f2003, -std=f2008
	   and -Wall.

	   Produce a warning when numerical constant expressions are
	   encountered, which yield an UNDERFLOW during compilation.

	   Warn if a user-defined procedure or module procedure has the same
	   name as an intrinsic; in this case, an explicit interface or
	   "EXTERNAL" or "INTRINSIC" declaration might be needed to get calls
	   later resolved to the desired intrinsic/procedure.  This option is
	   implied by -Wall.

	   Warn about unused dummy arguments. This option is implied by -Wall.

	   Contrary to gcc's meaning of -Wunused-parameter, gfortran's
	   implementation of this option does not warn about unused dummy
	   arguments (see -Wunused-dummy-argument), but about unused
	   "PARAMETER" values. -Wunused-parameter is not included in -Wall but
	   is implied by -Wall -Wextra.

	   By default, gfortran warns about any occasion of variables being
	   padded for proper alignment inside a "COMMON" block. This warning
	   can be turned off via -Wno-align-commons. See also -falign-commons.

	   Warn if any calls to functions are eliminated by the optimizations
	   enabled by the -ffrontend-optimize option.

	   Warn when the compiler might insert code to for allocation or
	   reallocation of an allocatable array variable of intrinsic type in
	   intrinsic assignments.  In hot loops, the Fortran 2003 reallocation
	   feature may reduce the performance.	If the array is already
	   allocated with the correct shape, consider using a whole-array
	   array-spec (e.g. "(:,:,:)") for the variable on the left-hand side
	   to prevent the reallocation check. Note that in some cases the
	   warning is shown, even if the compiler will optimize reallocation
	   checks away.	 For instance, when the right-hand side contains the
	   same variable multiplied by a scalar.  See also -frealloc-lhs.

	   Warn when the compiler inserts code to for allocation or
	   reallocation of an allocatable variable; this includes scalars and
	   derived types.

	   Warn when comparing real or complex types for equality or
	   inequality.	This option is implied by -Wextra.

	   Warn if the pointer in a pointer assignment might be longer than
	   the its target. This option is implied by -Wall.

	   Turns all warnings into errors.

       Some of these have no effect when compiling programs written in

   Options for debugging your program or GNU Fortran
       GNU Fortran has various special options that are used for debugging
       either your program or the GNU Fortran compiler.

	   Output the internal parse tree after translating the source program
	   into internal representation.  Only really useful for debugging the
	   GNU Fortran compiler itself.

	   Output the parse tree after front-end optimization.	Only really
	   useful for debugging the GNU Fortran compiler itself.

	   Output the internal parse tree after translating the source program
	   into internal representation.  Only really useful for debugging the
	   GNU Fortran compiler itself.	 This option is deprecated; use
	   "-fdump-fortran-original" instead.

	   Specify a list of floating point exception traps to enable.	On
	   most systems, if a floating point exception occurs and the trap for
	   that exception is enabled, a SIGFPE signal will be sent and the
	   program being aborted, producing a core file useful for debugging.
	   list is a (possibly empty) comma-separated list of the following
	   exceptions: invalid (invalid floating point operation, such as
	   "SQRT(-1.0)"), zero (division by zero), overflow (overflow in a
	   floating point operation), underflow (underflow in a floating point
	   operation), inexact (loss of precision during operation), and
	   denormal (operation performed on a denormal value).	The first five
	   exceptions correspond to the five IEEE 754 exceptions, whereas the
	   last one (denormal) is not part of the IEEE 754 standard but is
	   available on some common architectures such as x86.

	   The first three exceptions (invalid, zero, and overflow) often
	   indicate serious errors, and unless the program has provisions for
	   dealing with these exceptions, enabling traps for these three
	   exceptions is probably a good idea.

	   Many, if not most, floating point operations incur loss of
	   precision due to rounding, and hence the "ffpe-trap=inexact" is
	   likely to be uninteresting in practice.

	   By default no exception traps are enabled.

	   When a serious runtime error is encountered or a deadly signal is
	   emitted (segmentation fault, illegal instruction, bus error,
	   floating-point exception, and the other POSIX signals that have the
	   action core), the Fortran runtime library tries to output a
	   backtrace of the error. "-fno-backtrace" disables the backtrace
	   generation. This option only has influence for compilation of the
	   Fortran main program.

   Options for directory search
       These options affect how GNU Fortran searches for files specified by
       the "INCLUDE" directive and where it searches for previously compiled

       It also affects the search paths used by cpp when used to preprocess
       Fortran source.

	   These affect interpretation of the "INCLUDE" directive (as well as
	   of the "#include" directive of the cpp preprocessor).

	   Also note that the general behavior of -I and "INCLUDE" is pretty
	   much the same as of -I with "#include" in the cpp preprocessor,
	   with regard to looking for header.gcc files and other such things.

	   This path is also used to search for .mod files when previously
	   compiled modules are required by a "USE" statement.

	   This option specifies where to put .mod files for compiled modules.
	   It is also added to the list of directories to searched by an "USE"

	   The default is the current directory.

       -fintrinsic-modules-path dir
	   This option specifies the location of pre-compiled intrinsic
	   modules, if they are not in the default location expected by the

   Influencing the linking step
       These options come into play when the compiler links object files into
       an executable output file. They are meaningless if the compiler is not
       doing a link step.

	   On systems that provide libgfortran as a shared and a static
	   library, this option forces the use of the static version. If no
	   shared version of libgfortran was built when the compiler was
	   configured, this option has no effect.

   Influencing runtime behavior
       These options affect the runtime behavior of programs compiled with GNU

	   Specify the representation of data for unformatted files.  Valid
	   values for conversion are: native, the default; swap, swap between
	   big- and little-endian; big-endian, use big-endian representation
	   for unformatted files; little-endian, use little-endian
	   representation for unformatted files.

	   This option has an effect only when used in the main program.  The
	   "CONVERT" specifier and the GFORTRAN_CONVERT_UNIT environment
	   variable override the default specified by -fconvert.

	   Specify the length of record markers for unformatted files.	Valid
	   values for length are 4 and 8.  Default is 4.  This is different
	   from previous versions of gfortran, which specified a default
	   record marker length of 8 on most systems.  If you want to read or
	   write files compatible with earlier versions of gfortran, use

	   Specify the maximum length for a subrecord.	The maximum permitted
	   value for length is 2147483639, which is also the default.  Only
	   really useful for use by the gfortran testsuite.

	   When enabled, floating point numbers of value zero with the sign
	   bit set are written as negative number in formatted output and
	   treated as negative in the "SIGN" intrinsic.	 -fno-sign-zero does
	   not print the negative sign of zero values (or values rounded to
	   zero for I/O) and regards zero as positive number in the "SIGN"
	   intrinsic for compatibility with Fortran 77. The default is

   Options for code generation conventions
       These machine-independent options control the interface conventions
       used in code generation.

       Most of them have both positive and negative forms; the negative form
       of -ffoo would be -fno-foo.  In the table below, only one of the forms
       is listed---the one which is not the default.  You can figure out the
       other form by either removing no- or adding it.

	   Treat each program unit (except those marked as RECURSIVE) as if
	   the "SAVE" statement were specified for every local variable and
	   array referenced in it. Does not affect common blocks. (Some
	   Fortran compilers provide this option under the name -static or
	   -save.)  The default, which is -fautomatic, uses the stack for
	   local variables smaller than the value given by
	   -fmax-stack-var-size.  Use the option -frecursive to use no static

	   Generate code designed to be compatible with code generated by g77
	   and f2c.

	   The calling conventions used by g77 (originally implemented in f2c)
	   require functions that return type default "REAL" to actually
	   return the C type "double", and functions that return type
	   "COMPLEX" to return the values via an extra argument in the calling
	   sequence that points to where to store the return value.  Under the
	   default GNU calling conventions, such functions simply return their
	   results as they would in GNU C---default "REAL" functions return
	   the C type "float", and "COMPLEX" functions return the GNU C type
	   "complex".  Additionally, this option implies the
	   -fsecond-underscore option, unless -fno-second-underscore is
	   explicitly requested.

	   This does not affect the generation of code that interfaces with
	   the libgfortran library.

	   Caution: It is not a good idea to mix Fortran code compiled with
	   -ff2c with code compiled with the default -fno-f2c calling
	   conventions as, calling "COMPLEX" or default "REAL" functions
	   between program parts 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.

	   Do not transform names of entities specified in the Fortran source
	   file by appending underscores to them.

	   With -funderscoring in effect, GNU Fortran appends one underscore
	   to external names with no underscores.  This is done to ensure
	   compatibility with code produced by many UNIX Fortran compilers.

	   Caution: The default behavior of GNU Fortran is incompatible with
	   f2c and g77, please use the -ff2c option if you want object files
	   compiled with GNU Fortran to be compatible with object code created
	   with these tools.

	   Use of -fno-underscoring is not recommended unless you are
	   experimenting with issues such as integration of GNU Fortran into
	   existing system environments (vis-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 GNU Fortran code
	   with other languages.

	   Note that just because the names match does not mean that the
	   interface implemented by GNU Fortran for an external name matches
	   the interface implemented by some other language for that same
	   name.  That is, getting code produced by GNU Fortran to link to
	   code produced by some other compiler using this or any other method
	   can be only a small part of the overall solution---getting the code
	   generated by both compilers to agree on issues other than naming
	   can require significant effort, and, unlike naming disagreements,
	   linkers normally cannot detect disagreements in these other areas.

	   Also, note that with -fno-underscoring, the lack of appended
	   underscores introduces the very real possibility that a user-
	   defined external name 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 GNU Fortran 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.

	   This flag causes the compiler to resolve and translate each
	   procedure in a file separately.

	   By default, the whole file is parsed and placed in a single front-
	   end tree.  During resolution, in addition to all the usual checks
	   and fixups, references to external procedures that are in the same
	   file effect resolution of that procedure, if not already done, and
	   a check of the interfaces.  The dependences are resolved by
	   changing the order in which the file is translated into the backend
	   tree.  Thus, a procedure that is referenced is translated before
	   the reference and the duplication of backend tree declarations

	   The -fno-whole-file option is deprecated and may lead to wrong

	   By default, GNU Fortran appends an underscore to external names.
	   If this option is used GNU Fortran appends two underscores to names
	   with underscores and one underscore to external names with no
	   underscores.	 GNU Fortran also appends two underscores to internal
	   names with underscores to avoid naming collisions with external

	   This 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

	       Disable coarray support; using coarray declarations and image-
	       control statements will produce a compile-time error. (Default)

	       Single-image mode, i.e. "num_images()" is always one.

	   lib Library-based coarray parallelization; a suitable GNU Fortran
	       coarray library needs to be linked.

	   Enable the generation of run-time checks; the argument shall be a
	   comma-delimited list of the following keywords.

	   all Enable all run-time test of -fcheck.

	       Warns at run time when for passing an actual argument a
	       temporary array had to be generated. The information generated
	       by this warning is sometimes useful in optimization, in order
	       to avoid such temporaries.

	       Note: The warning is only printed once per location.

	       Enable generation of run-time checks for array subscripts and
	       against the declared minimum and maximum values.	 It also
	       checks array indices for assumed and deferred shape arrays
	       against the actual allocated bounds and ensures that all string
	       lengths are equal for character array constructors without an
	       explicit typespec.

	       Some checks require that -fcheck=bounds is set for the
	       compilation of the main program.

	       Note: In the future this may also include other forms of
	       checking, e.g., checking substring references.

	   do  Enable generation of run-time checks for invalid modification
	       of loop iteration variables.

	   mem Enable generation of run-time checks for memory allocation.
	       Note: This option does not affect explicit allocations using
	       the "ALLOCATE" statement, which will be always checked.

	       Enable generation of run-time checks for pointers and

	       Enable generation of run-time checks for recursively called
	       subroutines and functions which are not marked as recursive.
	       See also -frecursive.  Note: This check does not work for
	       OpenMP programs and is disabled if used together with
	       -frecursive and -fopenmp.

	   Deprecated alias for -fcheck=bounds.

	   Deprecated alias for -fcheck=array-temps.

	   This option can be used to increase the upper limit permitted in
	   array constructors.	The code below requires this option to expand
	   the array at compile time.

		   program test
		   implicit none
		   integer j
		   integer, parameter :: n = 100000
		   integer, parameter :: i(n) = (/ (2*j, j = 1, n) /)
		   print '(10(I0,1X))', i
		   end program test

	   Caution:  This option can lead to long compile times and
	   excessively large object files.

	   The default value for n is 65535.

	   This option specifies the size in bytes of the largest array that
	   will be put on the stack; if the size is exceeded static memory is
	   used (except in procedures marked as RECURSIVE). Use the option
	   -frecursive to allow for recursive procedures which do not have a
	   RECURSIVE attribute or for parallel programs. Use -fno-automatic to
	   never use the stack.

	   This option currently only affects local arrays declared with
	   constant bounds, and may not apply to all character variables.
	   Future versions of GNU Fortran may improve this behavior.

	   The default value for n is 32768.

	   Adding this option will make the Fortran compiler put all local
	   arrays, even those of unknown size onto stack memory.  If your
	   program uses very large local arrays it is possible that you will
	   have to extend your runtime limits for stack memory on some
	   operating systems. This flag is enabled by default at optimization
	   level -Ofast.

	   This option tells GNU Fortran to pack derived type members as
	   closely as possible.	 Code compiled with this option is likely to
	   be incompatible with code compiled without this option, and may
	   execute slower.

	   In some circumstances GNU Fortran may pass assumed shape array
	   sections via a descriptor describing a noncontiguous area of
	   memory.  This option adds code to the function prologue to repack
	   the data into a contiguous block at runtime.

	   This should result in faster accesses to the array.	However it can
	   introduce significant overhead to the function call, especially
	   when the passed data is noncontiguous.

	   This option is provided for interoperability with C code that was
	   compiled with the -fshort-enums option.  It will make GNU Fortran
	   choose the smallest "INTEGER" kind a given enumerator set will fit
	   in, and give all its enumerators this kind.

	   This option will make gfortran generate calls to BLAS functions for
	   some matrix operations like "MATMUL", instead of using our own
	   algorithms, if the size of the matrices involved is larger than a
	   given limit (see -fblas-matmul-limit).  This may be profitable if
	   an optimized vendor BLAS library is available.  The BLAS library
	   will have to be specified at link time.

	   Only significant when -fexternal-blas is in effect.	Matrix
	   multiplication of matrices with size larger than (or equal to) n
	   will be performed by calls to BLAS functions, while others will be
	   handled by gfortran internal algorithms. If the matrices involved
	   are not square, the size comparison is performed using the
	   geometric mean of the dimensions of the argument and result

	   The default value for n is 30.

	   Allow indirect recursion by forcing all local arrays to be
	   allocated on the stack. This flag cannot be used together with
	   -fmax-stack-var-size= or -fno-automatic.

	   The -finit-local-zero option instructs the compiler to initialize
	   local "INTEGER", "REAL", and "COMPLEX" variables to zero, "LOGICAL"
	   variables to false, and "CHARACTER" variables to a string of null
	   bytes.  Finer-grained initialization options are provided by the
	   -finit-integer=n, -finit-real=<zero|inf|-inf|nan|snan> (which also
	   initializes the real and imaginary parts of local "COMPLEX"
	   variables), -finit-logical=<true|false>, and -finit-character=n
	   (where n is an ASCII character value) options.  These options do
	   not initialize

	   o   allocatable arrays

	   o   components of derived type variables

	   o   variables that appear in an "EQUIVALENCE" statement.

	   (These limitations may be removed in future releases).

	   Note that the -finit-real=nan option initializes "REAL" and
	   "COMPLEX" variables with a quiet NaN. For a signalling NaN use
	   -finit-real=snan; note, however, that compile-time optimizations
	   may convert them into quiet NaN and that trapping needs to be
	   enabled (e.g. via -ffpe-trap).

	   Finally, note that enabling any of the -finit-* options will
	   silence warnings that would have been emitted by -Wuninitialized
	   for the affected local variables.

	   By default, gfortran enforces proper alignment of all variables in
	   a "COMMON" block by padding them as needed. On certain platforms
	   this is mandatory, on others it increases performance. If a
	   "COMMON" block is not declared with consistent data types
	   everywhere, this padding can cause trouble, and -fno-align-commons
	   can be used to disable automatic alignment. The same form of this
	   option should be used for all files that share a "COMMON" block.
	   To avoid potential alignment issues in "COMMON" blocks, it is
	   recommended to order objects from largest to smallest.

	   By default the parentheses in expression are honored for all
	   optimization levels such that the compiler does not do any re-
	   association. Using -fno-protect-parens allows the compiler to
	   reorder "REAL" and "COMPLEX" expressions to produce faster code.
	   Note that for the re-association optimization -fno-signed-zeros and
	   -fno-trapping-math need to be in effect. The parentheses protection
	   is enabled by default, unless -Ofast is given.

	   An allocatable left-hand side of an intrinsic assignment is
	   automatically (re)allocated if it is either unallocated or has a
	   different shape. The option is enabled by default except when
	   -std=f95 is given. See also -Wrealloc-lhs.

	   Functions with identical argument lists are eliminated within
	   statements, regardless of whether these functions are marked "PURE"
	   or not. For example, in

		     a = f(b,c) + f(b,c)

	   there will only be a single call to "f".  This option only works if
	   -ffrontend-optimize is in effect.

	   This option performs front-end optimization, based on manipulating
	   parts the Fortran parse tree.  Enabled by default by any -O option.
	   Optimizations enabled by this option include elimination of
	   identical function calls within expressions, removing unnecessary
	   calls to "TRIM" in comparisons and assignments and replacing
	   TRIM(a) with "a(1:LEN_TRIM(a))".  It can be deselected by
	   specifying -fno-frontend-optimize.

       The gfortran compiler currently does not make use of any environment
       variables to control its operation above and beyond those that affect
       the operation of gcc.

       For instructions on reporting bugs, see

       gpl(7), gfdl(7), fsf-funding(7), cpp(1), gcov(1), gcc(1), as(1), ld(1),
       gdb(1), adb(1), dbx(1), sdb(1) and the Info entries for gcc, cpp,
       gfortran, as, ld, binutils and gdb.

       See the Info entry for gfortran for contributors to GCC and GNU

       Copyright (c) 2004-2013 Free Software Foundation, Inc.

       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.3 or
       any later version published by the Free Software Foundation; with the
       Invariant Sections being "Funding Free Software", the Front-Cover Texts
       being (a) (see below), and with the Back-Cover Texts being (b) (see
       below).	A copy of the license is included in the gfdl(7) man page.

       (a) The FSF's Front-Cover Text is:

	    A GNU Manual

       (b) The FSF's Back-Cover Text is:

	    You have freedom to copy and modify this GNU Manual, like GNU
	    software.  Copies published by the Free Software Foundation raise
	    funds for GNU development.

gcc-4.8.5			  2015-06-23			   GFORTRAN(1)