From f2393c38b13637c661c6484b7f5aab559406ceaf Mon Sep 17 00:00:00 2001
From: stevenj <stevenj@alum.mit.edu>
Date: Thu, 29 Jul 2010 22:35:46 -0400
Subject: [PATCH] handle missing C99/IEEE copysign function, e.g. for WWin32;
 thanks to Benoit Scherrer for the bug report

darcs-hash:20100730023546-c8de0-2d82e58615ba8036734a2b104aefb4a53a88f9b5.gz
---
 configure.ac      | 8 ++++++++
 util/nlopt-util.h | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/configure.ac b/configure.ac
index 7c88f3d..b5c6d2a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,6 +86,14 @@ if test "$ok" = "yes"; then
 fi
 AC_MSG_RESULT(${ok})
 
+AC_MSG_CHECKING([for copysign])
+AC_TRY_LINK([#include <math.h>
+], [double x = copysign(3.14159, -2.7183);], ok=yes, ok=no)
+if test "$ok" = "yes"; then
+	AC_DEFINE(HAVE_COPYSIGN,1,[Define if the copysign function/macro is available.])
+fi
+AC_MSG_RESULT(${ok})
+
 dnl -----------------------------------------------------------------------
 
 if test "x$with_cxx" = xyes; then
diff --git a/util/nlopt-util.h b/util/nlopt-util.h
index 9b4f51f..222ce6f 100644
--- a/util/nlopt-util.h
+++ b/util/nlopt-util.h
@@ -35,6 +35,11 @@
 #  define HUGE_VAL REPLACEMENT_HUGE_VAL
 #endif
 
+#ifndef HAVE_COPYSIGN
+   /* not quite right for y == -0, but good enough for us */
+#  define copysign(x, y) ((y) < 0 ? -fabs(x) : fabs(x))
+#endif
+
 #ifdef __cplusplus
 extern "C"
 {
-- 
2.30.2