1 files changed, 7 insertions, 0 deletions
diff --git a/missing/isinf.c b/missing/isinf.c
index e44ef6c3c1..c9e49c6795 100644
--- a/missing/isinf.c
+++ b/missing/isinf.c
@@ -28,12 +28,19 @@ isinf(n)
 #include <ieeefp.h>
 #endif
 
+/* 
+ * isinf may be provided only as a macro.
+ * ex. HP-UX, Solaris 10
+ * http://www.gnu.org/software/automake/manual/autoconf/Function-Portability.html
+ */
+#ifndef isinf
 int
 isinf(n)
     double n;
 {
     return (!finite(n) && !isnan(n));
 }
+#endif
 
 #else