acx_lapack

This macro looks for a library that implements the LAPACK linear-algebra interface (see http://www.netlib.org/lapack/). On success, it sets the LAPACK_LIBS output variable to hold the requisite library linkages.

To link with LAPACK, you should link with:

     $LAPACK_LIBS $BLAS_LIBS $LIBS $FLIBS

in that order. BLAS_LIBS is the output variable of the ACX_BLAS macro, called automatically. FLIBS is the output variable of the AC_F77_LIBRARY_LDFLAGS macro (called if necessary by ACX_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.

The user may also use --with-lapack=<lib> in order to use some specific LAPACK 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 LAPACK and BLAS libraries.

ACTION-IF-FOUND is a list of shell commands to run if a LAPACK 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_LAPACK.

AC_DEFUN([ACX_LAPACK], [
AC_REQUIRE([ACX_BLAS])
acx_lapack_ok=no

AC_ARG_WITH(lapack,
        [AC_HELP_STRING([--with-lapack=<lib>], [use LAPACK library <lib>])])
case $with_lapack in
        yes | "") ;;
        no) acx_lapack_ok=disable ;;
        -* | */* | *.a | *.so | *.so.* | *.o) LAPACK_LIBS="$with_lapack" ;;
        *) LAPACK_LIBS="-l$with_lapack" ;;
esac

# Get fortran linker name of LAPACK function to check for.
AC_F77_FUNC(cheev)

# We cannot use LAPACK if BLAS is not found
if test "x$acx_blas_ok" != xyes; then
        acx_lapack_ok=noblas
fi

# First, check LAPACK_LIBS environment variable
if test "x$LAPACK_LIBS" != x; then
        save_LIBS="$LIBS"; LIBS="$LAPACK_LIBS $BLAS_LIBS $LIBS $FLIBS"
        AC_MSG_CHECKING([for $cheev in $LAPACK_LIBS])
        AC_TRY_LINK_FUNC($cheev, [acx_lapack_ok=yes], [LAPACK_LIBS=""])
        AC_MSG_RESULT($acx_lapack_ok)
        LIBS="$save_LIBS"
        if test acx_lapack_ok = no; then
                LAPACK_LIBS=""
        fi
fi

# LAPACK linked to by default?  (is sometimes included in BLAS lib)
if test $acx_lapack_ok = no; then
        save_LIBS="$LIBS"; LIBS="$LIBS $BLAS_LIBS $FLIBS"
        AC_CHECK_FUNC($cheev, [acx_lapack_ok=yes])
        LIBS="$save_LIBS"
fi

# Generic LAPACK library?
for lapack in lapack lapack_rs6k; do
        if test $acx_lapack_ok = no; then
                save_LIBS="$LIBS"; LIBS="$BLAS_LIBS $LIBS"
                AC_CHECK_LIB($lapack, $cheev,
                    [acx_lapack_ok=yes; LAPACK_LIBS="-l$lapack"], [], [$FLIBS])
                LIBS="$save_LIBS"
        fi
done

AC_SUBST(LAPACK_LIBS)

# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
if test x"$acx_lapack_ok" = xyes; then
        ifelse([$1],,AC_DEFINE(HAVE_LAPACK,1,[Define if you have LAPACK library.]),[$1])
        :
else
        acx_lapack_ok=no
        $2
fi
])dnl ACX_LAPACK