dnl @synopsis ACX_BLAS([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
dnl
dnl This macro looks for a library that implements the BLAS
dnl linear-algebra interface (see http://www.netlib.org/blas/). On
dnl success, it sets the BLAS_LIBS output variable to hold the
dnl requisite library linkages.
dnl
dnl To link with BLAS, you should link with:
dnl
dnl 	$BLAS_LIBS $LIBS $FLIBS
dnl
dnl in that order. FLIBS is the output variable of the
dnl AC_F77_LIBRARY_LDFLAGS macro (called if necessary by ACX_BLAS), and
dnl is sometimes necessary in order to link with F77 libraries. Users
dnl will also need to use AC_F77_DUMMY_MAIN (see the autoconf manual),
dnl for the same reason.
dnl
dnl Many libraries are searched for, from ATLAS to CXML to ESSL. The
dnl user may also use --with-blas=<lib> in order to use some specific
dnl BLAS library <lib>. In order to link successfully, however, be
dnl aware that you will probably need to use the same Fortran compiler
dnl (which can be set via the F77 env. var.) as was used to compile the
dnl BLAS library.
dnl
dnl ACTION-IF-FOUND is a list of shell commands to run if a BLAS
dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands to
dnl run it if it is not found. If ACTION-IF-FOUND is not specified, the
dnl default action will define HAVE_BLAS.
dnl
dnl This macro requires autoconf 2.50 or later.
dnl
dnl @category InstalledPackages
dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
dnl @version 2001-12-13
dnl @license GPLWithACException
dnl modified by salvatore.filippone@uniroma2.it
dnl shifted check for ESSL as it was generating erroneous results on
dnl AIX SP5.
dnl 

AC_DEFUN([ACX_BLAS], [
AC_PREREQ(2.50)
AC_REQUIRE([AC_F77_LIBRARY_LDFLAGS])
acx_blas_ok=no

AC_ARG_WITH(blas,
	[AC_HELP_STRING([--with-blas=<lib>], [use BLAS library <lib>])])
case $with_blas in
	yes | "") ;;
	no) acx_blas_ok=disable ;;
	-* | */* | *.a | *.so | *.so.* | *.o) BLAS_LIBS="$with_blas" ;;
	*) BLAS_LIBS="-l$with_blas" ;;
esac

# Get fortran linker names of BLAS functions to check for.
AC_F77_FUNC(sgemm)
AC_F77_FUNC(dgemm)

acx_blas_save_LIBS="$LIBS"
LIBS="$LIBS $FLIBS"

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


# BLAS in ATLAS library? (http://math-atlas.sourceforge.net/)
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(atlas, ATL_xerbla,
		[AC_CHECK_LIB(f77blas, $sgemm,
		[AC_CHECK_LIB(cblas, cblas_dgemm,
			[acx_blas_ok=yes
			 BLAS_LIBS="-lcblas -lf77blas -latlas"],
			[], [-lf77blas -latlas])],
			[], [-latlas])])

fi

# BLAS in PhiPACK libraries? (requires generic BLAS lib, too)
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(blas, $sgemm,
		[AC_CHECK_LIB(dgemm, $dgemm,
		[AC_CHECK_LIB(sgemm, $sgemm,
			[acx_blas_ok=yes; BLAS_LIBS="-lsgemm -ldgemm -lblas"],
			[], [-lblas])],
			[], [-lblas])])
fi

# BLAS in Alpha CXML library?
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(cxml, $sgemm, [acx_blas_ok=yes;BLAS_LIBS="-lcxml"])
fi

# BLAS in Alpha DXML library? (now called CXML, see above)
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(dxml, $sgemm, [acx_blas_ok=yes;BLAS_LIBS="-ldxml"])

fi

# BLAS in Sun Performance library?
if test $acx_blas_ok = no; then
	if test "x$GCC" != xyes; then # only works with Sun CC
		AC_CHECK_LIB(sunmath, acosp,
			[AC_CHECK_LIB(sunperf, $sgemm,
        			[BLAS_LIBS="-xlic_lib=sunperf -lsunmath"
                                 acx_blas_ok=yes],[],[-lsunmath])])

	fi
fi

# BLAS in SCSL library?  (SGI/Cray Scientific Library)
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(scs, $sgemm, [acx_blas_ok=yes; BLAS_LIBS="-lscs"])
fi

# BLAS in SGIMATH library?
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(complib.sgimath, $sgemm,
		     [acx_blas_ok=yes; BLAS_LIBS="-lcomplib.sgimath"])
fi

# BLAS in IBM ESSL library? (requires generic BLAS lib, too)
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(blas, $sgemm,
		[AC_CHECK_LIB(essl, $sgemm,
			[acx_blas_ok=yes; BLAS_LIBS="-lessl -lblas"],
			[], [-lblas $FLIBS])])
fi
# BLAS linked to by default?  (happens on some supercomputers)
if test $acx_blas_ok = no; then
	save_LIBS="$LIBS"; LIBS="$LIBS"
	AC_TRY_LINK_FUNC($sgemm, [acx_blas_ok=yes], [BLAS_LIBS=""])
dnl	AC_CHECK_FUNC($sgemm, [acx_blas_ok=yes])
	LIBS="$save_LIBS"
fi

# Generic BLAS library?
if test $acx_blas_ok = no; then
	AC_CHECK_LIB(blas, $sgemm, [acx_blas_ok=yes; BLAS_LIBS="-lblas"])
fi

AC_SUBST(BLAS_LIBS)

LIBS="$acx_blas_save_LIBS"

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