glibc/math/s_cacosl.c
Joseph Myers 01dbacd22a Fix cacos (+Inf + finite*i) in round-downward mode (bug 16928).
According to C99/C11 Annex G, cacos applied to a value with real part
+Inf and finite imaginary part should produce a result with real part
+0.  glibc wrongly produces a result with real part -0 in FE_DOWNWARD
mode.  This patch fixes this by checking for zero results in the
relevant case of non-finite arguments (where there should never be a
result with -0 real part), and converts the tests of cacos to
ALL_RM_TEST.

Tested x86_64 and x86 and ulps updated accordingly.

	[BZ #16928]
	* math/s_cacos.c (__cacos): Ensure zero real part of result from
	non-finite arguments is +0.
	* math/s_cacosf.c (__cacosf): Likewise.
	* math/s_cacosl.c (__cacosl): Likewise.
	* math/libm-test.inc (cacos_test): Use ALL_RM_TEST.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
2014-05-14 12:37:24 +00:00

55 lines
1.6 KiB
C

/* Return cosine of complex long double value.
Copyright (C) 1997-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <complex.h>
#include <math.h>
__complex__ long double
__cacosl (__complex__ long double x)
{
__complex__ long double y;
__complex__ long double res;
int rcls = fpclassify (__real__ x);
int icls = fpclassify (__imag__ x);
if (rcls <= FP_INFINITE || icls <= FP_INFINITE
|| (rcls == FP_ZERO && icls == FP_ZERO))
{
y = __casinl (x);
__real__ res = M_PI_2l - __real__ y;
if (__real__ res == 0.0L)
__real__ res = 0.0L;
__imag__ res = -__imag__ y;
}
else
{
__real__ y = -__imag__ x;
__imag__ y = __real__ x;
y = __kernel_casinhl (y, 1);
__real__ res = __imag__ y;
__imag__ res = __real__ y;
}
return res;
}
weak_alias (__cacosl, cacosl)