1 /* Return arc hyperbole tangent for double value.
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 Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the 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 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
24 #include "math_private.h"
28 __catanh (__complex__ double x)
30 __complex__ double res;
31 int rcls = fpclassify (__real__ x);
32 int icls = fpclassify (__imag__ x);
34 if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
36 if (icls == FP_INFINITE)
38 __real__ res = __copysign (0.0, __real__ x);
39 __imag__ res = __copysign (M_PI_2, __imag__ x);
41 else if (rcls == FP_INFINITE || rcls == FP_ZERO)
43 __real__ res = __copysign (0.0, __real__ x);
45 __imag__ res = __copysign (M_PI_2, __imag__ x);
47 __imag__ res = __nan ("");
51 __real__ res = __nan ("");
52 __imag__ res = __nan ("");
55 else if (rcls == FP_ZERO && icls == FP_ZERO)
63 i2 = __imag__ x * __imag__ x;
65 num = 1.0 + __real__ x;
68 den = 1.0 - __real__ x;
71 __real__ res = 0.25 * (__ieee754_log (num) - __ieee754_log (den));
73 den = 1 - __real__ x * __real__ x - i2;
75 __imag__ res = 0.5 * __ieee754_atan2 (2.0 * __imag__ x, den);
80 weak_alias (__catanh, catanh)
82 strong_alias (__catanh, __catanhl)
83 weak_alias (__catanh, catanhl)