Update.
[glibc.git] / sysdeps / libm-ieee754 / s_ctanh.c
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1 /* Complex hyperbole tangent for double.
2 Copyright (C) 1997 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public License as
8 published by the Free Software Foundation; either version 2 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Library General Public License for more details.
16 You should have received a copy of the GNU Library General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If not,
18 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
21 #include <complex.h>
22 #include <fenv.h>
23 #include <math.h>
25 #include "math_private.h"
28 __complex__ double
29 __ctanh (__complex__ double x)
31 __complex__ double res;
33 if (!isfinite (__real__ x) || !isfinite (__imag__ x))
35 if (__isinf (__real__ x))
37 __real__ res = __copysign (1.0, __real__ x);
38 __imag__ res = __copysign (0.0, __imag__ x);
40 else if (__imag__ x == 0.0)
42 res = x;
44 else
46 __real__ res = __nan ("");
47 __imag__ res = __nan ("");
49 #ifdef FE_INVALID
50 if (__isinf (__imag__ x))
51 feraiseexcept (FE_INVALID);
52 #endif
55 else
57 double sin2ix, cos2ix;
58 double den;
60 __sincos (2.0 * __imag__ x, &sin2ix, &cos2ix);
62 den = (__ieee754_cosh (2.0 * __real__ x) + cos2ix);
64 __real__ res = __ieee754_sinh (2.0 * __real__ x) / den;
65 __imag__ res = sin2ix / den;
68 return res;
70 weak_alias (__ctanh, ctanh)
71 #ifdef NO_LONG_DOUBLE
72 strong_alias (__ctanh, __ctanhl)
73 weak_alias (__ctanh, ctanhl)
74 #endif