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authorSzabolcs Nagy <nsz@port70.net>2013-09-05 16:57:46 +0000
committerSzabolcs Nagy <nsz@port70.net>2013-09-05 16:57:46 +0000
commitf4d9bfb3a986f2c25ec023426b4fb222130af75f (patch)
treeb2fd726519f60975ffd2fef8365014b6f98b1b99 /src/math/atanhl.c
parentafa2aaccea6e9f8c55809abb6471dc9aaa402711 (diff)
downloadmusl-f4d9bfb3a986f2c25ec023426b4fb222130af75f.tar.gz
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.c15
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;
}