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.