* sysdeps/ieee754/dbl-64/s_expm1.c: Set errno for overflow.
[glibc.git] / math / s_ctanl.c
blob89379a5ff9a37cbc3ce9a2d3ce55cc7e571bce52
1 /* Complex tangent function for long double.
2 Copyright (C) 1997, 2005 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 <fenv.h>
23 #include <math.h>
25 #include "math_private.h"
28 __complex__ long double
29 __ctanl (__complex__ long double x)
31 __complex__ long double res;
33 if (!isfinite (__real__ x) || !isfinite (__imag__ x))
35 if (__isinfl (__imag__ x))
37 __real__ res = __copysignl (0.0, __real__ x);
38 __imag__ res = __copysignl (1.0, __imag__ x);
40 else if (__real__ x == 0.0)
42 res = x;
44 else
46 __real__ res = __nanl ("");
47 __imag__ res = __nanl ("");
49 #ifdef FE_INVALID
50 if (__isinfl (__real__ x))
51 feraiseexcept (FE_INVALID);
52 #endif
55 else
57 long double sin2rx, cos2rx;
58 long double den;
60 __sincosl (2.0 * __real__ x, &sin2rx, &cos2rx);
62 den = cos2rx + __ieee754_coshl (2.0 * __imag__ x);
65 if (den == 0.0)
67 __complex__ long double ez = __cexpl (1.0i * x);
68 __complex__ long double emz = __cexpl (-1.0i * x);
70 res = (ez - emz) / (ez + emz) * -1.0i;
72 else
74 __real__ res = sin2rx / den;
75 __imag__ res = __ieee754_sinhl (2.0 * __imag__ x) / den;
79 return res;
81 weak_alias (__ctanl, ctanl)