From: Zack Weinberg <zackw@panix.com>
Date: Fri, 1 Sep 2017 15:19:47 +0000 (-0400)
Subject: math/math.h (HUGE_VAL): Improve commentary.
X-Git-Tag: glibc-2.27~995
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a617bd119f1b36a7ff2d2fdecf0d2f56970d0288;p=thirdparty%2Fglibc.git

math/math.h (HUGE_VAL): Improve commentary.
---

diff --git a/ChangeLog b/ChangeLog
index 4f8a12ca7c2..32b304b8acb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2017-09-01  Zack Weinberg  <zackw@panix.com>
+
+	* math/math.h (HUGE_VAL): Improve commentary.
+
 2017-09-01  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 	    Andreas Schwab  <schwab@suse.de>
 
diff --git a/math/math.h b/math/math.h
index bbc1ab9bfab..547b36d10ed 100644
--- a/math/math.h
+++ b/math/math.h
@@ -37,11 +37,16 @@ __BEGIN_DECLS
 /* Gather machine dependent type support.  */
 #include <bits/floatn.h>
 
-/* Value returned on overflow.  On all IEEE754 machines, this is
-   +Infinity.  */
+/* Value returned on overflow.  With IEEE 754 floating point, this is
+   +Infinity, otherwise the largest representable positive value.  */
 #if __GNUC_PREREQ (3, 3)
 # define HUGE_VAL (__builtin_huge_val ())
 #else
+/* This may provoke compiler warnings, and may not be rounded to
+   +Infinity in all IEEE 754 rounding modes, but is the best that can
+   be done in ISO C while remaining a constant expression.  10,000 is
+   greater than the maximum (decimal) exponent for all supported
+   floating-point formats and widths.  */
 # define HUGE_VAL 1e10000
 #endif
 #ifdef __USE_ISOC99