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authorJoseph Myers <joseph@codesourcery.com>2013-04-02 22:54:00 +0000
committerJoseph Myers <joseph@codesourcery.com>2013-04-02 22:54:00 +0000
commit52ce486045074d0af0298082f94e385e6b2fe443 (patch)
tree472a67e3c1b2881643aaa315cbfc32fee80e38a0 /math/s_cacoshl.c
parente7906a4789f9f6ac4cd4a99522832753887a8cc7 (diff)
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Fix cacosh inaccuracy and spurious exceptions (bug 15327).
Diffstat (limited to 'math/s_cacoshl.c')
-rw-r--r--math/s_cacoshl.c33
1 files changed, 13 insertions, 20 deletions
diff --git a/math/s_cacoshl.c b/math/s_cacoshl.c
index 7fd0b82..c110fab 100644
--- a/math/s_cacoshl.c
+++ b/math/s_cacoshl.c
@@ -64,32 +64,25 @@ __cacoshl (__complex__ long double x)
__real__ res = 0.0;
__imag__ res = __copysignl (M_PI_2l, __imag__ x);
}
- /* The factor 16 is just a guess. */
- else if (16.0L * fabsl (__imag__ x) < fabsl (__real__ x))
- {
- /* Kahan's formula which avoid cancellation through subtraction in
- some cases. */
- res = 2.0L * __clogl (__csqrtl ((x + 1.0L) / 2.0L)
- + __csqrtl ((x - 1.0L) / 2.0L));
- if (signbit (__real__ res))
- __real__ res = 0.0L;
- }
else
{
__complex__ long double y;
- __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
- __imag__ y = 2.0 * __real__ x * __imag__ x;
-
- y = __csqrtl (y);
+ __real__ y = -__imag__ x;
+ __imag__ y = __real__ x;
- if (signbit (__real__ x))
- y = -y;
+ y = __kernel_casinhl (y, 1);
- __real__ y += __real__ x;
- __imag__ y += __imag__ x;
-
- res = __clogl (y);
+ if (signbit (__imag__ x))
+ {
+ __real__ res = __real__ y;
+ __imag__ res = -__imag__ y;
+ }
+ else
+ {
+ __real__ res = -__real__ y;
+ __imag__ res = __imag__ y;
+ }
}
return res;