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| author | Szabolcs Nagy <nsz@port70.net> | 2013-09-05 16:57:46 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <nsz@port70.net> | 2013-09-05 16:57:46 +0000 |
| commit | f4d9bfb3a986f2c25ec023426b4fb222130af75f (patch) | |
| tree | b2fd726519f60975ffd2fef8365014b6f98b1b99 /src/math/atanhl.c | |
| parent | afa2aaccea6e9f8c55809abb6471dc9aaa402711 (diff) | |
| download | musl-f4d9bfb3a986f2c25ec023426b4fb222130af75f.tar.gz musl-f4d9bfb3a986f2c25ec023426b4fb222130af75f.tar.xz musl-f4d9bfb3a986f2c25ec023426b4fb222130af75f.zip | |
math: fix atanh (overflow and underflow issues)
in atanh exception handling was left to the called log functions, but the argument to those functions could underflow or overflow. use double_t and float_t to avoid some useless stores on x86
Diffstat (limited to 'src/math/atanhl.c')
| -rw-r--r-- | src/math/atanhl.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/src/math/atanhl.c b/src/math/atanhl.c index 72a1e345..f63d60b1 100644 --- a/src/math/atanhl.c +++ b/src/math/atanhl.c @@ -17,11 +17,18 @@ long double atanhl(long double x) u.i.se = e; x = u.f; - if (e < 0x3fff - 1) { - /* |x| < 0.5, up to 1.7ulp error */ - x = 0.5*log1pl(2*x + 2*x*x/(1-x)); + if (e < 0x3ff - 1) { + if (e < 0x3ff - LDBL_MANT_DIG/2) { + /* handle underflow */ + if (e == 0) + FORCE_EVAL((float)x); + } else { + /* |x| < 0.5, up to 1.7ulp error */ + x = 0.5*log1pl(2*x + 2*x*x/(1-x)); + } } else { - x = 0.5*log1pl(2*x/(1-x)); + /* avoid overflow */ + x = 0.5*log1pl(2*(x/(1-x))); } return s ? -x : x; } |