From 2ca725c594e0c186d928dc0823be7d8b5976112c Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 27 Feb 2015 17:48:37 +0000 Subject: Fix ldbl-96, ldbl-128ibm atanhl inaccuracy (bug 18046, bug 18047). The threshold in ldbl-96 atanhl for when to return the argument, 0x1p-28, is a bit too big, and that in ldbl-128ibm atanhl is much too big (the relevant condition being x^3/3 being < 0.5ulp of x), resulting in errors a bit above the limits of those considered acceptable in glibc in the ldbl-96 case, and in large errors in the ldbl-128ibm case. This patch changes those implementations to use more appropriate thresholds and adds tests around the thresholds for various formats. Tested for x86_64, x86 and powerpc. x86_64 and x86 ulps updated accordingly. [BZ #18046] [BZ #18047] * sysdeps/ieee754/ldbl-128ibm/e_atanhl.c (__ieee754_atanhl): Use 0x1p-56L as threshold for just returning the argument. * sysdeps/ieee754/ldbl-96/e_atanhl.c (__ieee754_atanhl): Use 0x1p-32L as threshold for just returning the argument. * math/auto-libm-test-in: Add more tests of atanh. * math/auto-libm-test-out: Regenerated. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulp: Likewise. --- sysdeps/ieee754/ldbl-96/e_atanhl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'sysdeps/ieee754/ldbl-96') diff --git a/sysdeps/ieee754/ldbl-96/e_atanhl.c b/sysdeps/ieee754/ldbl-96/e_atanhl.c index 4c29243695..305d50e309 100644 --- a/sysdeps/ieee754/ldbl-96/e_atanhl.c +++ b/sysdeps/ieee754/ldbl-96/e_atanhl.c @@ -52,9 +52,9 @@ __ieee754_atanhl(long double x) return (x-x)/(x-x); if(ix==0x3fff) return x/zero; - if(ix<0x3fe3) { + if(ix<0x3fdf) { math_force_eval(huge+x); - return x; /* x<2**-28 */ + return x; /* x<2**-32 */ } SET_LDOUBLE_EXP(x,ix); if(ix<0x3ffe) { /* x < 0.5 */ -- cgit 1.4.1