sysdeps/libm-ieee754/s_ctan.c

   1 /* Complex tangent function 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.
   5
   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.
  10
  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.
  15
  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.  */
  20
  21 #include <complex.h>
  22 #include <math.h>
  23
  24 #include "math_private.h"
  25
  26
  27 __complex__ double
  28 __ctan (__complex__ double x)
  29 {
  30   __complex__ double res;
  31
  32   if (!finite (__real__ x) || !finite (__imag__ x))
  33     {
  34       if (__isinf (__imag__ x))
  35         {
  36           __real__ res = __copysign (0.0, __real__ x);
  37           __imag__ res = __copysign (1.0, __imag__ x);
  38         }
  39       else if (__real__ x == 0.0)
  40         {
  41           res = x;
  42         }
  43       else
  44         {
  45           __real__ res = __nan ("");
  46           __imag__ res = __nan ("");
  47         }
  48     }
  49   else
  50     {
  51       double den = (__cos (2.0 * __real__ x)
  52                     + __ieee754_cosh (2.0 * __imag__ x));
  53
  54       __real__ res = __sin (2.0 * __real__ x) / den;
  55       __imag__ res = __ieee754_sinh (2.0 * __imag__ x) / den;
  56     }
  57
  58   return res;
  59 }
  60 weak_alias (__ctan, ctan)
  61 #ifdef NO_LONG_DOUBLE
  62 strong_alias (__ctan, __ctanl)
  63 weak_alias (__ctan, ctanl)
  64 #endif