math/s_cacosh.c

   1 /* Return arc hyperbole cosine for double value.
   2    Copyright (C) 1997-2015 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 <math.h>
  22 #include <math_private.h>
  23
  24
  25 __complex__ double
  26 __cacosh (__complex__ double x)
  27 {
  28   __complex__ double res;
  29   int rcls = fpclassify (__real__ x);
  30   int icls = fpclassify (__imag__ x);
  31
  32   if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
  33     {
  34       if (icls == FP_INFINITE)
  35         {
  36           __real__ res = HUGE_VAL;
  37
  38           if (rcls == FP_NAN)
  39             __imag__ res = __nan ("");
  40           else
  41             __imag__ res = __copysign ((rcls == FP_INFINITE
  42                                         ? (__real__ x < 0.0
  43                                            ? M_PI - M_PI_4 : M_PI_4)
  44                                         : M_PI_2), __imag__ x);
  45         }
  46       else if (rcls == FP_INFINITE)
  47         {
  48           __real__ res = HUGE_VAL;
  49
  50           if (icls >= FP_ZERO)
  51             __imag__ res = __copysign (signbit (__real__ x) ? M_PI : 0.0,
  52                                        __imag__ x);
  53           else
  54             __imag__ res = __nan ("");
  55         }
  56       else
  57         {
  58           __real__ res = __nan ("");
  59           __imag__ res = __nan ("");
  60         }
  61     }
  62   else if (rcls == FP_ZERO && icls == FP_ZERO)
  63     {
  64       __real__ res = 0.0;
  65       __imag__ res = __copysign (M_PI_2, __imag__ x);
  66     }
  67   else
  68     {
  69       __complex__ double y;
  70
  71       __real__ y = -__imag__ x;
  72       __imag__ y = __real__ x;
  73
  74       y = __kernel_casinh (y, 1);
  75
  76       if (signbit (__imag__ x))
  77         {
  78           __real__ res = __real__ y;
  79           __imag__ res = -__imag__ y;
  80         }
  81       else
  82         {
  83           __real__ res = -__real__ y;
  84           __imag__ res = __imag__ y;
  85         }
  86     }
  87
  88   return res;
  89 }
  90 weak_alias (__cacosh, cacosh)
  91 #ifdef NO_LONG_DOUBLE
  92 strong_alias (__cacosh, __cacoshl)
  93 weak_alias (__cacosh, cacoshl)
  94 #endif