Re: isnan in fortran

[c.]

On 11 Apr 2012, at 13:24, John W. Eaton wrote:

> Uh, except that I have the test and some syntax wrong.  How about
> 
>       logical function isnan (x)
>       double precision x
>       isnan = x .ne. x
>       return
>       end
> 
> jwe


OK, so what about the configure test below?
How do I get to add misc/isnan.f to the list of files to compile if the test 
fails?
c.


diff -r b2bf5896ab51 configure.ac
--- a/configure.ac      Mon Apr 09 21:11:18 2012 +0200
+++ b/configure.ac      Wed Apr 11 13:32:32 2012 +0200
@@ -593,6 +593,8 @@
   AC_MSG_ERROR([in order to build octave, you must have a compatible Fortran 
compiler or wrapper script for f2c that functions as a Fortran compiler 
installed and in your path.  See the file INSTALL for more information.])
 fi
 
+OCTAVE_CHECK_FORTRAN_HAVE_ISNAN
+
 OCTAVE_CHECK_FORTRAN_INTEGER_SIZE
 if test "x$octave_cv_fortran_integer_size" = xno; then
   if $USE_64_BIT_IDX_T; then
diff -r b2bf5896ab51 m4/acinclude.m4
--- a/m4/acinclude.m4   Mon Apr 09 21:11:18 2012 +0200
+++ b/m4/acinclude.m4   Wed Apr 11 13:32:32 2012 +0200
@@ -329,6 +329,29 @@
   fi
 ])
 dnl
+dnl Check to see whether Fortran compiler has the intrinsic function ISNAN.
+dnl
+AC_DEFUN([OCTAVE_CHECK_FORTRAN_HAVE_ISNAN], [
+  AC_LANG_PUSH(Fortran 77)
+dnl        AC_CACHE_CHECK
+dnl          (
+dnl            [whether $F77 has the intrinsic function ISNAN]
+dnl            ,
+dnl            [octave_cv_fortran_have_isnan]
+dnl            ,
+dnl            [
+              AC_COMPILE_IFELSE(
+[      program foo
+      double precision x
+      logical y
+      y = isnan(x)
+      end], [AC_DEFINE([HAVE_FORTRAN_ISNAN], [1], [Define to 1 if your fortran 
compiler has ISNAN.])],
+                )
+dnl            ]
+dnl          )
+  AC_LANG_POP(Fortran 77)      
+])
+dnl
 dnl Check to see whether the default Fortran INTEGER is 64 bits wide.
 dnl
 AC_DEFUN([OCTAVE_CHECK_FORTRAN_INTEGER_SIZE], [