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authorZack Weinberg <zackw@panix.com>2017-09-01 11:19:47 -0400
committerZack Weinberg <zackw@panix.com>2017-09-01 11:19:47 -0400
commita617bd119f1b36a7ff2d2fdecf0d2f56970d0288 (patch)
treeafc91c5ecccb67e03ac2d4b436b5a56a53fc93bd /math/math.h
parentce870587d5055437619680700ee5663a3cec66f6 (diff)
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math/math.h (HUGE_VAL): Improve commentary.
Diffstat (limited to 'math/math.h')
-rw-r--r--math/math.h9
1 files changed, 7 insertions, 2 deletions
diff --git a/math/math.h b/math/math.h
index bbc1ab9bfa..547b36d10e 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