Declare `logb' only if HAVE_LOGB is defined.

diff --git a/src/floatfns.c b/src/floatfns.c
index 5cc499979f8f8592448670ab0d0d2de7223c6057..b31f0baee2744a756f8fd750ba4230c8ad4c432f 100644 (file)
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -65,10 +65,10 @@ Lisp_Object Qarith_error;
 
 #include <math.h>
 
-#ifndef hpux
-/* These declarations are omitted on some systems, like Ultrix.  */
+/* This declaration is omitted on some systems, like Ultrix.  */
+#if !defined (hpux) && defined (HAVE_LOGB)
 extern double logb ();
-#endif
+#endif /* !hpux && HAVE_LOGB */
 
 #if defined(DOMAIN) && defined(SING) && defined(OVERFLOW)
     /* If those are defined, then this is probably a `matherr' machine. */