From 396e3ecf3e8f0f05bd7eeaf995a3f0c2327a6cd6 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Thu, 2 Jan 2014 16:33:06 +0000 Subject: Fix ldbl-128ibm acoshl inaccuracy (bug 16384). This patch fixes bug 16384, ldbl-128ibm acoshl inaccuracy, which showed up while attempting to regenerate ulps for powerpc-nofpu for 2.19. There were two separate problems, use of __log1p instead of __log1pl and an insufficiently accurate constant value for log 2 (which this patch replaces by use of M_LN2l), each of which could cause substantial inaccuracy in affected cases. Tested for powerpc-nofpu. * sysdeps/ieee754/ldbl-128ibm/e_acoshl.c (ln2): Initialize with M_LN2l. (__ieee754_acoshl): Use __log1pl not __log1p. --- sysdeps/ieee754/ldbl-128ibm/e_acoshl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'sysdeps') diff --git a/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c b/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c index 8a4a5bb7b9..b0b33f7520 100644 --- a/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c +++ b/sysdeps/ieee754/ldbl-128ibm/e_acoshl.c @@ -29,7 +29,7 @@ static const long double one = 1.0L, -ln2 = 6.93147180559945286227e-01L; /* 0x3FE62E42, 0xFEFA39EF */ +ln2 = M_LN2l; long double __ieee754_acoshl(long double x) @@ -56,7 +56,7 @@ __ieee754_acoshl(long double x) return __ieee754_logl(2.0*x-one/(x+__ieee754_sqrtl(t-one))); } else { /* 1