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| author | Joseph Myers <joseph@codesourcery.com> | 2013-03-27 14:38:44 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2013-03-27 14:38:44 +0000 |
| commit | 3a7182a14becbf3149419bdbaff4388b636c9f31 (patch) | |
| tree | 16616a6c0915ec7099fcd318204f8e5741571b29 /math/k_casinh.c | |
| parent | 28831a9a671b109e49d0a4ddce00a08d734bfc97 (diff) | |
| download | glibc-3a7182a14becbf3149419bdbaff4388b636c9f31.zip glibc-3a7182a14becbf3149419bdbaff4388b636c9f31.tar.gz glibc-3a7182a14becbf3149419bdbaff4388b636c9f31.tar.bz2 | |
Fix casinh inaccuracy near i, imaginary part > 1 (bug 15307).
Diffstat (limited to 'math/k_casinh.c')
| -rw-r--r-- | math/k_casinh.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/math/k_casinh.c b/math/k_casinh.c index 45845e2..4cb232a 100644 --- a/math/k_casinh.c +++ b/math/k_casinh.c @@ -77,6 +77,38 @@ __kernel_casinh (__complex__ double x, int adj) else __imag__ res = __ieee754_atan2 (s, rx); } + else if (ix > 1.0 && ix < 1.5 && rx < 0.5) + { + if (rx < DBL_EPSILON * DBL_EPSILON) + { + double ix2m1 = (ix + 1.0) * (ix - 1.0); + double s = __ieee754_sqrt (ix2m1); + + __real__ res = __log1p (2.0 * (ix2m1 + ix * s)) / 2.0; + if (adj) + __imag__ res = __ieee754_atan2 (rx, __copysign (s, __imag__ x)); + else + __imag__ res = __ieee754_atan2 (s, rx); + } + else + { + double ix2m1 = (ix + 1.0) * (ix - 1.0); + double rx2 = rx * rx; + double f = rx2 * (2.0 + rx2 + 2.0 * ix * ix); + double d = __ieee754_sqrt (ix2m1 * ix2m1 + f); + double dp = d + ix2m1; + double dm = f / dp; + double r1 = __ieee754_sqrt ((dm + rx2) / 2.0); + double r2 = rx * ix / r1; + + __real__ res = __log1p (rx2 + dp + 2.0 * (rx * r1 + ix * r2)) / 2.0; + if (adj) + __imag__ res = __ieee754_atan2 (rx + r1, __copysign (ix + r2, + __imag__ x)); + else + __imag__ res = __ieee754_atan2 (ix + r2, rx + r1); + } + } else if (ix == 1.0 && rx < 0.5) { if (rx < DBL_EPSILON / 8.0) |