This macro looks for a library that implements the BLAS linear-algebra interface (see http://www.netlib.org/blas/). On success, it sets the BLAS_LIBS output variable to hold the requisite library linkages.
To link with BLAS, you should link with:
$BLAS_LIBS $LIBS $FLIBS
in that order. FLIBS is the output variable of the AC_F77_LIBRARY_LDFLAGS macro (called if necessary by AX_BLAS), and is sometimes necessary in order to link with F77 libraries. Users will also need to use AC_F77_DUMMY_MAIN (see the autoconf manual), for the same reason.
Many libraries are searched for, from ATLAS to CXML to ESSL. The user may also use –with-blas=<lib> in order to use some specific BLAS library <lib>. In order to link successfully, however, be aware that you will probably need to use the same Fortran compiler (which can be set via the F77 env. var.) as was used to compile the BLAS library.
ACTION-IF-FOUND is a list of shell commands to run if a BLAS library 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_BLAS.
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