diff options
| author | Joseph Myers <joseph@codesourcery.com> | 2012-03-14 11:53:32 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2012-03-14 11:53:32 +0000 |
| commit | e456826d7a539fb322bb9719297bd386eded8e32 (patch) | |
| tree | 5a0b1e8979b004c88796e199fac827a0d8817207 /math/s_csqrt.c | |
| parent | 6278569b6c1ee1b6e2b36af059e699233da0b88b (diff) | |
Fix csqrt overflow/underflow (bug 13841).
Diffstat (limited to 'math/s_csqrt.c')
| -rw-r--r-- | math/s_csqrt.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/math/s_csqrt.c b/math/s_csqrt.c index 76585e889c..002ea5fdc2 100644 --- a/math/s_csqrt.c +++ b/math/s_csqrt.c @@ -1,5 +1,5 @@ /* Complex square root of double value. - Copyright (C) 1997, 1998, 2005, 2011 Free Software Foundation, Inc. + Copyright (C) 1997-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Based on an algorithm by Stephen L. Moshier <moshier@world.std.com>. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. @@ -21,7 +21,7 @@ #include <complex.h> #include <math.h> #include <math_private.h> - +#include <float.h> __complex__ double __csqrt (__complex__ double x) @@ -83,6 +83,22 @@ __csqrt (__complex__ double x) else { double d, r, s; + 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, -2 * scale); + __imag__ x = __scalbn (__imag__ x, -2 * scale); + } + else if (fabs (__real__ x) < DBL_MIN + && fabs (__imag__ x) < DBL_MIN) + { + scale = -(DBL_MANT_DIG / 2); + __real__ x = __scalbn (__real__ x, -2 * scale); + __imag__ x = __scalbn (__imag__ x, -2 * scale); + } d = __ieee754_hypot (__real__ x, __imag__ x); /* Use the identity 2 Re res Im res = Im x @@ -98,6 +114,12 @@ __csqrt (__complex__ double x) r = fabs ((0.5 * __imag__ x) / s); } + if (scale) + { + r = __scalbn (r, scale); + s = __scalbn (s, scale); + } + __real__ res = r; __imag__ res = __copysign (s, __imag__ x); } |