@node ax_openmp
@unnumberedsec ax_openmp

@majorheading Synopsis

@smallexample
AX_OPENMP([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
@end smallexample

@majorheading Description

This macro tries to find out how to compile programs that use OpenMP a
standard API and set of compiler directives for parallel programming
(see http://www-unix.mcs/)

On success, it sets the OPENMP_CFLAGS/OPENMP_CXXFLAGS/OPENMP_F77FLAGS
output variable to the flag (e.g. -omp) used both to compile *and* link
OpenMP programs in the current language.

NOTE: You are assumed to not only compile your program with these flags,
but also link it with them as well.

If you want to compile everything with OpenMP, you should set:

@smallexample
  CFLAGS="$CFLAGS $OPENMP_CFLAGS"
  #OR#  CXXFLAGS="$CXXFLAGS $OPENMP_CXXFLAGS"
  #OR#  FFLAGS="$FFLAGS $OPENMP_FFLAGS"
@end smallexample

(depending on the selected language).

The user can override the default choice by setting the corresponding
environment variable (e.g. OPENMP_CFLAGS).

ACTION-IF-FOUND is a list of shell commands to run if an OpenMP flag is
found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it is
not found. If ACTION-IF-FOUND is not specified, the default action will
define HAVE_OPENMP.

@majorheading Source Code

Download the
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_openmp.m4,latest
version of @file{ax_openmp.m4}} or browse
@uref{http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=history;f=m4/ax_openmp.m4,the
macro's revision history}.

@majorheading License

@w{Copyright @copyright{} 2008 Steven G. Johnson @email{stevenj@@alum.mit.edu}} @* @w{Copyright @copyright{} 2015 John W. Peterson @email{jwpeterson@@gmail.com}} @* @w{Copyright @copyright{} 2016 Nick R. Papior @email{nickpapior@@gmail.com}}

This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.

You should have received a copy of the GNU General Public License along
with this program. If not, see <https://www.gnu.org/licenses/>.

As a special exception, the respective Autoconf Macro's copyright owner
gives unlimited permission to copy, distribute and modify the configure
scripts that are the output of Autoconf when processing the Macro. You
need not follow the terms of the GNU General Public License when using
or distributing such scripts, even though portions of the text of the
Macro appear in them. The GNU General Public License (GPL) does govern
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This special exception to the GPL applies to versions of the Autoconf
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exception to the GPL to apply to your modified version as well.