From d1d3431a3a9dd14501eedb701436bd5005b1db7d Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Wed, 7 Mar 2012 15:15:19 +0000 Subject: Fix signs of zeros from casinh, cacosh etc. (bug 10716). --- math/s_cacosh.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'math/s_cacosh.c') diff --git a/math/s_cacosh.c b/math/s_cacosh.c index 95bf005cd3..ef49088c3d 100644 --- a/math/s_cacosh.c +++ b/math/s_cacosh.c @@ -1,5 +1,5 @@ /* Return arc hyperbole cosine for double value. - Copyright (C) 1997, 2006, 2011 Free Software Foundation, Inc. + Copyright (C) 1997-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 1997. @@ -66,9 +66,13 @@ __cacosh (__complex__ double x) } /* The factor 16 is just a guess. */ else if (16.0 * fabs (__imag__ x) < fabs (__real__ x)) - /* Kahan's formula which avoid cancellation through subtraction in - some cases. */ - res = 2.0 * __clog (__csqrt ((x + 1.0) / 2.0) + __csqrt ((x - 1.0) / 2.0)); + { + /* Kahan's formula which avoid cancellation through subtraction in + some cases. */ + res = 2.0 * __clog (__csqrt ((x + 1.0) / 2.0) + __csqrt ((x - 1.0) / 2.0)); + if (signbit (__real__ res)) + __real__ res = 0.0; + } else { __complex__ double y; -- cgit 1.4.1