From c599f4f4d705ba215a2672b92baa1c29d9dd0735 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Thu, 15 Aug 2013 10:14:46 +0000 Subject: math: fix asin, atan, log1p, tanh to raise underflow on subnormal for these functions f(x)=x for small inputs, because f(0)=0 and f'(0)=1, but for subnormal values they should raise the underflow flag (required by annex F), if they are approximated by a polynomial around 0 then spurious underflow should be avoided (not required by annex F) all these functions should raise inexact flag for small x if x!=0, but it's not required by the standard and it does not seem a worthy goal, so support for it is removed in some cases. raising underflow: - x*x may not raise underflow for subnormal x if FLT_EVAL_METHOD!=0 - x*x may raise spurious underflow for normal x if FLT_EVAL_METHOD==0 - in case of double subnormal x, store x as float - in case of float subnormal x, store x*x as float --- src/math/sinh.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/math/sinh.c') diff --git a/src/math/sinh.c b/src/math/sinh.c index 47e36bfa..00022c4e 100644 --- a/src/math/sinh.c +++ b/src/math/sinh.c @@ -23,8 +23,8 @@ double sinh(double x) t = expm1(absx); if (w < 0x3ff00000) { if (w < 0x3ff00000 - (26<<20)) - /* note: inexact is raised by expm1 */ - /* note: this branch avoids underflow */ + /* note: inexact and underflow are raised by expm1 */ + /* note: this branch avoids spurious underflow */ return x; return h*(2*t - t*t/(t+1)); } -- cgit v1.2.1