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authorJoseph Myers <joseph@codesourcery.com>2013-04-30 11:27:35 +0000
committerJoseph Myers <joseph@codesourcery.com>2013-04-30 11:27:35 +0000
commitcaf84319c1614d8aa867d8db80219f4e9b1bf735 (patch)
tree08263d4ddcdf643fc258daeb43718821a2e2fbde /math/s_catanh.c
parent6dbe713d85fecc1bee99713d745413106af200b7 (diff)
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Fix catan, catanh inaccuracy from atan2 denominators near 0 (bug 15416).
Diffstat (limited to 'math/s_catanh.c')
-rw-r--r--math/s_catanh.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/math/s_catanh.c b/math/s_catanh.c
index 55c5628..5248cbc 100644
--- a/math/s_catanh.c
+++ b/math/s_catanh.c
@@ -89,7 +89,25 @@ __catanh (__complex__ double x)
__real__ res = 0.25 * __log1p (num / den);
}
- den = 1 - __real__ x * __real__ x - i2;
+ double absx, absy;
+
+ absx = fabs (__real__ x);
+ absy = fabs (__imag__ x);
+ if (absx < absy)
+ {
+ double t = absx;
+ absx = absy;
+ absy = t;
+ }
+
+ if (absx >= 1.0)
+ den = (1.0 - absx) * (1.0 + absx) - absy * absy;
+ else if (absx >= 0.75 && absy < DBL_EPSILON / 2.0)
+ den = (1.0 - absx) * (1.0 + absx);
+ else if (absx >= 0.75 || absy >= 0.5)
+ den = -__x2y2m1 (absx, absy);
+ else
+ den = (1.0 - absx) * (1.0 + absx) - absy * absy;
__imag__ res = 0.5 * __ieee754_atan2 (2.0 * __imag__ x, den);
}