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