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[glibc/history.git] / math / s_catanhf.c
blobd2422e61111a685b671a2b2b3a4724815956d258
1 /* Return arc hyperbole tangent for float 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
19 02111-1307 USA. */
21 #include <complex.h>
22 #include <math.h>
24 #include "math_private.h"
27 __complex__ float
28 __catanhf (__complex__ float x)
30 __complex__ float 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 = __copysignf (0.0, __real__ x);
39 __imag__ res = __copysignf (M_PI_2, __imag__ x);
41 else if (rcls == FP_INFINITE || rcls == FP_ZERO)
43 __real__ res = __copysignf (0.0, __real__ x);
44 if (icls >= FP_ZERO)
45 __imag__ res = __copysignf (M_PI_2, __imag__ x);
46 else
47 __imag__ res = __nanf ("");
49 else
51 __real__ res = __nanf ("");
52 __imag__ res = __nanf ("");
55 else if (rcls == FP_ZERO && icls == FP_ZERO)
57 res = x;
59 else
61 float i2, num, den;
63 i2 = __imag__ x * __imag__ x;
65 num = 1.0 + __real__ x;
66 num = i2 + num * num;
68 den = 1.0 - __real__ x;
69 den = i2 + den * den;
71 __real__ res = 0.25 * (__ieee754_logf (num) - __ieee754_logf (den));
73 den = 1 - __real__ x * __real__ x - i2;
75 __imag__ res = 0.5 * __ieee754_atan2f (2.0 * __imag__ x, den);
78 return res;
80 #ifndef __catanhf
81 weak_alias (__catanhf, catanhf)
82 #endif