sysdeps/ieee754/ldbl-128ibm/s_ctanl.c

   1 /* Complex tangent function for long double.  IBM extended format version.
   2    Copyright (C) 1997,2005,2006 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <complex.h>
  22 #include <fenv.h>
  23 #include <math.h>
  24 #include <math_ldbl_opt.h>
  25
  26 #include "math_private.h"
  27
  28
  29 __complex__ long double
  30 __ctanl (__complex__ long double x)
  31 {
  32   __complex__ long double res;
  33
  34   if (!isfinite (__real__ x) || !isfinite (__imag__ x))
  35     {
  36       if (__isinfl (__imag__ x))
  37         {
  38           __real__ res = __copysignl (0.0, __real__ x);
  39           __imag__ res = __copysignl (1.0, __imag__ x);
  40         }
  41       else if (__real__ x == 0.0)
  42         {
  43           res = x;
  44         }
  45       else
  46         {
  47           __real__ res = __nanl ("");
  48           __imag__ res = __nanl ("");
  49
  50 #ifdef FE_INVALID
  51           if (__isinfl (__real__ x))
  52             feraiseexcept (FE_INVALID);
  53 #endif
  54         }
  55     }
  56   else
  57     {
  58       long double sin2rx, cos2rx;
  59       long double den;
  60
  61       __sincosl (2.0 * __real__ x, &sin2rx, &cos2rx);
  62
  63       den = cos2rx + __ieee754_coshl (2.0 * __imag__ x);
  64
  65
  66       if (den == 0.0)
  67         {
  68           __complex__ long double ez = __cexpl (1.0i * x);
  69           __complex__ long double emz = __cexpl (-1.0i * x);
  70
  71           res = (ez - emz) / (ez + emz) * -1.0i;
  72         }
  73       else
  74         {
  75           __real__ res = sin2rx / den;
  76           __imag__ res = __ieee754_sinhl (2.0 * __imag__ x) / den;
  77         }
  78       /* __gcc_qmul does not respect -0.0 so we need the following fixup.  */
  79       if ((__real__ res == 0.0) && (__real__ x == 0.0))
  80         __real__ res = __real__ x;
  81
  82       if ((__real__ res == 0.0) && (__imag__ x == 0.0))
  83         __imag__ res = __imag__ x;
  84     }
  85
  86   return res;
  87 }
  88 long_double_symbol (libm, __ctanl, ctanl);