diff options
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; } |