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| author | Joseph Myers <joseph@codesourcery.com> | 2012-03-19 20:13:10 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2012-03-19 20:14:26 +0000 |
| commit | 1897ad44326bb7761dcda46132ae303f7288aba9 (patch) | |
| tree | fd8357b0066902deb5b6b9476b8c456f68ffc56e /math/s_clog.c | |
| parent | 7726d6a95d5a2c08c8d43186002f040b9b889c27 (diff) | |
| download | glibc-1897ad44326bb7761dcda46132ae303f7288aba9.tar.gz glibc-1897ad44326bb7761dcda46132ae303f7288aba9.tar.xz glibc-1897ad44326bb7761dcda46132ae303f7288aba9.zip | |
Fix clog overflow/underflow (bug 13629).
Diffstat (limited to 'math/s_clog.c')
| -rw-r--r-- | math/s_clog.c | 27 |
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 |