math/s_ctanf.c

   1 /* Complex tangent function for float.
   2    Copyright (C) 1997, 2005, 2011 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 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.
  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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <complex.h>
  21 #include <fenv.h>
  22 #include <math.h>
  23 #include <math_private.h>
  24
  25
  26 __complex__ float
  27 __ctanf (__complex__ float x)
  28 {
  29   __complex__ float res;
  30
  31   if (__builtin_expect (!isfinite (__real__ x) || !isfinite (__imag__ x), 0))
  32     {
  33       if (__isinf_nsf (__imag__ x))
  34         {
  35           __real__ res = __copysignf (0.0, __real__ x);
  36           __imag__ res = __copysignf (1.0, __imag__ x);
  37         }
  38       else if (__real__ x == 0.0)
  39         {
  40           res = x;
  41         }
  42       else
  43         {
  44           __real__ res = __nanf ("");
  45           __imag__ res = __nanf ("");
  46
  47           if (__isinf_nsf (__real__ x))
  48             feraiseexcept (FE_INVALID);
  49         }
  50     }
  51   else
  52     {
  53       float sin2rx, cos2rx;
  54       float den;
  55
  56       __sincosf (2.0 * __real__ x, &sin2rx, &cos2rx);
  57
  58       den = cos2rx + __ieee754_coshf (2.0 * __imag__ x);
  59
  60
  61       if (den == 0.0)
  62         {
  63           __complex__ float ez = __cexpf (1.0i * x);
  64           __complex__ float emz = __cexpf (-1.0i * x);
  65
  66           res = (ez - emz) / (ez + emz) * -1.0i;
  67         }
  68       else
  69         {
  70           __real__ res = sin2rx / den;
  71           __imag__ res = __ieee754_sinhf (2.0 * __imag__ x) / den;
  72         }
  73     }
  74
  75   return res;
  76 }
  77 #ifndef __ctanf
  78 weak_alias (__ctanf, ctanf)
  79 #endif