--- a/acx_blas_f77_func.m4
+++ b/acx_blas_f77_func.m4
@@ -1,4 +1,6 @@
-##### http://autoconf-archive.cryp.to/acx_blas_f77_func.html
+# ===========================================================================
+#           http://autoconf-archive.cryp.to/acx_blas_f77_func.html
+# ===========================================================================
 #
 # SYNOPSIS
 #
@@ -8,55 +10,51 @@
 # DESCRIPTION
 #
 #   These macros are intended as a supplement to the ACX_BLAS macro, to
-#   verify that BLAS functions with non-REAL or INTEGER are properly
-#   callable from Fortran. This is necessary, for example, if you want
-#   to build the LAPACK library on top of the BLAS.
+#   verify that BLAS functions are properly callable from Fortran. This is
+#   necessary, for example, if you want to build the LAPACK library on top
+#   of the BLAS.
 #
-#   ACX_BLAS_F77_FUNC uses the defined BLAS_LIBS and Fortran
-#   environment to check for compatibility, and takes a specific action
-#   in case of success, resp. failure, resp. cross-compilation.
+#   ACX_BLAS_F77_FUNC uses the defined BLAS_LIBS and Fortran environment to
+#   check for compatibility, and takes a specific action in case of success,
+#   resp. failure, resp. cross-compilation.
 #
-#   ACX_BLAS_WITH_F77_FUNC is a drop-in replacement wrapper for
-#   ACX_BLAS that calls ACX_BLAS_F77_FUNC after detecting a BLAS
-#   library and rejects it on failure (i.e. pretends that no library
-#   was found).
+#   ACX_BLAS_WITH_F77_FUNC is a drop-in replacement wrapper for ACX_BLAS
+#   that calls ACX_BLAS_F77_FUNC after detecting a BLAS library and rejects
+#   it on failure (i.e. pretends that no library was found).
 #
 # LAST MODIFICATION
 #
-#   2008-03-31
+#   2008-06-18
 #
 # COPYLEFT
 #
 #   Copyright (c) 2008 Jaroslav Hajek <highegg@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 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.
+#   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
-#   <http://www.gnu.org/licenses/>.
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://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 all other use of the material that
-#   constitutes the Autoconf Macro.
+#   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
+#   all other use of the material that constitutes the Autoconf Macro.
 #
-#   This special exception to the GPL applies to versions of the
-#   Autoconf Macro released by the Autoconf Macro Archive. When you
-#   make and distribute a modified version of the Autoconf Macro, you
-#   may extend this special exception to the GPL to apply to your
-#   modified version as well.
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Macro Archive. When you make and
+#   distribute a modified version of the Autoconf Macro, you may extend this
+#   special exception to the GPL to apply to your modified version as well.
 
 AC_DEFUN([ACX_BLAS_F77_FUNC], [
 AC_PREREQ(2.50)
@@ -83,13 +81,38 @@
       ]]),[acx_blas_lsame_fcall_ok=yes],
 	[acx_blas_lsame_fcall_ok=no])
 	AC_MSG_RESULT([$acx_blas_lsame_fcall_ok])
+# ISAMAX check (INTEGER return values)
+	AC_MSG_CHECKING([whether ISAMAX is called correctly from Fortran])
+	AC_RUN_IFELSE(AC_LANG_PROGRAM(,[[
+      integer isamax,i
+      external isamax
+      real a(2)
+      a(1) = 1e0
+      a(2) = -2e0
+      i = isamax(2,a,1)
+      if (i.ne.2) stop 1
+      ]]),[acx_blas_isamax_fcall_ok=yes],
+	[acx_blas_isamax_fcall_ok=no])
+	AC_MSG_RESULT([$acx_blas_isamax_fcall_ok])
+# SDOT check (REAL return values)
+	AC_MSG_CHECKING([whether DDOT is called correctly from Fortran])
+	AC_RUN_IFELSE(AC_LANG_PROGRAM(,[[
+      real sdot,a(1),b(1),w
+      external sdot
+      a(1) = 1e0
+      b(1) = 2e0
+      w = sdot(1,a,1,b,1)
+      if (w .ne. a(1)*b(1)) stop 1
+      ]]),[acx_blas_sdot_fcall_ok=yes],
+	[acx_blas_sdot_fcall_ok=no])
+	AC_MSG_RESULT([$acx_blas_sdot_fcall_ok])
 # DDOT check (DOUBLE return values)
 	AC_MSG_CHECKING([whether DDOT is called correctly from Fortran])
 	AC_RUN_IFELSE(AC_LANG_PROGRAM(,[[
       double precision ddot,a(1),b(1),w
       external ddot
-      a(1) = 1e0
-      b(1) = 2e0
+      a(1) = 1d0
+      b(1) = 2d0
       w = ddot(1,a,1,b,1)
       if (w .ne. a(1)*b(1)) stop 1
       ]]),[acx_blas_ddot_fcall_ok=yes],
@@ -124,6 +147,7 @@
 
 # if any of the tests failed, reject the BLAS library
 	if test $acx_blas_lsame_fcall_ok = yes \
+		-a $acx_blas_sdot_fcall_ok = yes \
 		-a $acx_blas_ddot_fcall_ok = yes \
 		-a $acx_blas_cdotu_fcall_ok = yes \
 		-a $acx_blas_zdotu_fcall_ok = yes ; then