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Fix sign of zero part from ctan / ctanh when argument infinite (bug 17118).

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C99/C11 Annex G specifies the sign of the zero part of the result of
ctan (x +/- i * Inf) and ctanh (+/-Inf + i * y).  This patch fixes glibc
to follow that specification, along the lines I described in my review
of Andreas's previous patch for this issue
<https://sourceware.org/ml/libc-alpha/2014-08/msg00142.html>.

Tested for x86_64.

2015-09-17  Joseph Myers  <joseph@codesourcery.com>
	    Andreas Schwab  <schwab@suse.de>

	[BZ #17118]
	* math/s_ctan.c (__ctan): Determine sign of zero real part of
	result when imaginary part of argument is infinite using sine and
	cosine.
	* math/s_ctanf.c (__ctanf): Likewise.
	* math/s_ctanl.c (__ctanl): Likewise.
	* math/s_ctanh.c (__ctanh): Determine sign of zero imaginary part
	of result when real part of argument is infinite using sine and
	cosine.
	* math/s_ctanhf.c (__ctanhf): Likewise.
	* math/s_ctanhl.c (__ctanhl): Likewise.
	* math/libm-test.inc (ctan_test_data): Add more tests of ctan.
	(ctanh_test_data): Add more tests of ctanh.
This commit is contained in:
Joseph Myers
2015-09-17 21:21:39 +00:00
parent b8682397ab
commit 61f8937898
9 changed files with 198 additions and 11 deletions
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9
math/s_ctanl.c
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@ -39,7 +39,14 @@ __ctanl (__complex__ long double x)
{
if (__isinf_nsl (__imag__ x))
{
__real__ res = __copysignl (0.0, __real__ x);
if (isfinite (__real__ x) && fabsl (__real__ x) > 1.0L)
{
long double sinrx, cosrx;
__sincosl (__real__ x, &sinrx, &cosrx);
__real__ res = __copysignl (0.0L, sinrx * cosrx);
}
else
__real__ res = __copysignl (0.0, __real__ x);
__imag__ res = __copysignl (1.0, __imag__ x);
}
else if (__real__ x == 0.0)