summaryrefslogtreecommitdiff
path: root/math/s_clog.c
diff options
context:
space:
mode:
authorJoseph Myers <joseph@codesourcery.com>2012-03-19 20:13:10 +0000
committerJoseph Myers <joseph@codesourcery.com>2012-03-19 20:14:26 +0000
commit1897ad44326bb7761dcda46132ae303f7288aba9 (patch)
treefd8357b0066902deb5b6b9476b8c456f68ffc56e /math/s_clog.c
parent7726d6a95d5a2c08c8d43186002f040b9b889c27 (diff)
Fix clog overflow/underflow (bug 13629).
Diffstat (limited to 'math/s_clog.c')
-rw-r--r--math/s_clog.c27
1 files changed, 23 insertions, 4 deletions
diff --git a/math/s_clog.c b/math/s_clog.c
index 5bbca00388..15e5e9c678 100644
--- a/math/s_clog.c
+++ b/math/s_clog.c
@@ -1,5 +1,5 @@
/* Compute complex natural logarithm.
- Copyright (C) 1997, 2011 Free Software Foundation, Inc.
+ Copyright (C) 1997-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
@@ -20,7 +20,7 @@
#include <complex.h>
#include <math.h>
#include <math_private.h>
-
+#include <float.h>
__complex__ double
__clog (__complex__ double x)
@@ -40,8 +40,27 @@ __clog (__complex__ double x)
else if (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1))
{
/* Neither real nor imaginary part is NaN. */
- __real__ result = __ieee754_log (__ieee754_hypot (__real__ x,
- __imag__ x));
+ double d;
+ int scale = 0;
+
+ if (fabs (__real__ x) > DBL_MAX / 2.0
+ || fabs (__imag__ x) > DBL_MAX / 2.0)
+ {
+ scale = -1;
+ __real__ x = __scalbn (__real__ x, scale);
+ __imag__ x = __scalbn (__imag__ x, scale);
+ }
+ else if (fabs (__real__ x) < DBL_MIN
+ && fabs (__imag__ x) < DBL_MIN)
+ {
+ scale = DBL_MANT_DIG;
+ __real__ x = __scalbn (__real__ x, scale);
+ __imag__ x = __scalbn (__imag__ x, scale);
+ }
+
+ d = __ieee754_hypot (__real__ x, __imag__ x);
+
+ __real__ result = __ieee754_log (d) - scale * M_LN2;
__imag__ result = __ieee754_atan2 (__imag__ x, __real__ x);
}
else