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authorJoseph Myers <joseph@codesourcery.com>2012-07-26 11:31:35 +0000
committerJoseph Myers <joseph@codesourcery.com>2012-07-26 11:31:35 +0000
commitda865e95bcf9a5365de78fa6b5c681aca0a1bb46 (patch)
tree783e2a5f2befa846dc208ec14b7dcde164c7b205 /math/s_clog10.c
parent3129cfc6ec7be65a0bdc1f82432ee421c1c65a77 (diff)
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Improve clog, clog10 handling of values with real or imaginary part 1 (bug 13629).
Diffstat (limited to 'math/s_clog10.c')
-rw-r--r--math/s_clog10.c36
1 files changed, 27 insertions, 9 deletions
diff --git a/math/s_clog10.c b/math/s_clog10.c
index cf5fb8a0b5..b733b048b9 100644
--- a/math/s_clog10.c
+++ b/math/s_clog10.c
@@ -44,21 +44,21 @@ __clog10 (__complex__ double x)
{
/* Neither real nor imaginary part is NaN. */
double absx = fabs (__real__ x), absy = fabs (__imag__ x);
- double d;
int scale = 0;
+ if (absx < absy)
+ {
+ double t = absx;
+ absx = absy;
+ absy = t;
+ }
+
if (absx > DBL_MAX / 2.0)
{
scale = -1;
absx = __scalbn (absx, scale);
absy = (absy >= DBL_MIN * 2.0 ? __scalbn (absy, scale) : 0.0);
}
- else if (absy > DBL_MAX / 2.0)
- {
- scale = -1;
- absx = (absx >= DBL_MIN * 2.0 ? __scalbn (absx, scale) : 0.0);
- absy = __scalbn (absy, scale);
- }
else if (absx < DBL_MIN && absy < DBL_MIN)
{
scale = DBL_MANT_DIG;
@@ -66,9 +66,27 @@ __clog10 (__complex__ double x)
absy = __scalbn (absy, scale);
}
- d = __ieee754_hypot (absx, absy);
+ if (absx == 1.0 && scale == 0)
+ {
+ double absy2 = absy * absy;
+ if (absy2 <= DBL_MIN * 2.0 * M_LN10)
+ {
+#if __FLT_EVAL_METHOD__ == 0
+ __real__ result = (absy2 / 2.0 - absy2 * absy2 / 4.0) * M_LOG10E;
+#else
+ volatile double force_underflow = absy2 * absy2 / 4.0;
+ __real__ result = (absy2 / 2.0 - force_underflow) * M_LOG10E;
+#endif
+ }
+ else
+ __real__ result = __log1p (absy2) * (M_LOG10E / 2.0);
+ }
+ else
+ {
+ double d = __ieee754_hypot (absx, absy);
+ __real__ result = __ieee754_log10 (d) - scale * M_LOG10_2;
+ }
- __real__ result = __ieee754_log10 (d) - scale * M_LOG10_2;
__imag__ result = M_LOG10E * __ieee754_atan2 (__imag__ x, __real__ x);
}
else