diff options
Diffstat (limited to 'math/s_clog10.c')
| -rw-r--r-- | math/s_clog10.c | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/math/s_clog10.c b/math/s_clog10.c index 3eb9c518a8..9d366d6f2b 100644 --- a/math/s_clog10.c +++ b/math/s_clog10.c @@ -1,5 +1,5 @@ /* Compute complex base 10 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 +20,10 @@ #include <complex.h> #include <math.h> #include <math_private.h> +#include <float.h> +/* log_10 (2). */ +#define M_LOG10_2 0.3010299956639811952137388947244930267682 __complex__ double __clog10 (__complex__ double x) @@ -40,8 +43,27 @@ __clog10 (__complex__ double x) else if (__builtin_expect (rcls != FP_NAN && icls != FP_NAN, 1)) { /* Neither real nor imaginary part is NaN. */ - __real__ result = __ieee754_log10 (__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_log10 (d) - scale * M_LOG10_2; __imag__ result = M_LOG10E * __ieee754_atan2 (__imag__ x, __real__ x); } else |