aboutsummaryrefslogtreecommitdiff
path: root/math/s_clog10.c
diff options
context:
space:
mode:
Diffstat (limited to 'math/s_clog10.c')
-rw-r--r--math/s_clog10.c28
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