math/s_casinh.c

   1 /* Return arc hyperbole sine for double value.
   2    Copyright (C) 1997, 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, 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 <math.h>
  23 #include <math_private.h>
  24
  25
  26 __complex__ double
  27 __casinh (__complex__ double x)
  28 {
  29   __complex__ double res;
  30   int rcls = fpclassify (__real__ x);
  31   int icls = fpclassify (__imag__ x);
  32
  33   if (rcls <= FP_INFINITE || icls <= FP_INFINITE)
  34     {
  35       if (icls == FP_INFINITE)
  36         {
  37           __real__ res = __copysign (HUGE_VAL, __real__ x);
  38
  39           if (rcls == FP_NAN)
  40             __imag__ res = __nan ("");
  41           else
  42             __imag__ res = __copysign (rcls >= FP_ZERO ? M_PI_2 : M_PI_4,
  43                                        __imag__ x);
  44         }
  45       else if (rcls <= FP_INFINITE)
  46         {
  47           __real__ res = __real__ x;
  48           if ((rcls == FP_INFINITE && icls >= FP_ZERO)
  49               || (rcls == FP_NAN && icls == FP_ZERO))
  50             __imag__ res = __copysign (0.0, __imag__ x);
  51           else
  52             __imag__ res = __nan ("");
  53         }
  54       else
  55         {
  56           __real__ res = __nan ("");
  57           __imag__ res = __nan ("");
  58         }
  59     }
  60   else if (rcls == FP_ZERO && icls == FP_ZERO)
  61     {
  62       res = x;
  63     }
  64   else
  65     {
  66       __complex__ double y;
  67
  68       __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) + 1.0;
  69       __imag__ y = 2.0 * __real__ x * __imag__ x;
  70
  71       y = __csqrt (y);
  72
  73       __real__ y += __real__ x;
  74       __imag__ y += __imag__ x;
  75
  76       res = __clog (y);
  77     }
  78
  79   return res;
  80 }
  81 weak_alias (__casinh, casinh)
  82 #ifdef NO_LONG_DOUBLE
  83 strong_alias (__casinh, __casinhl)
  84 weak_alias (__casinh, casinhl)
  85 #endif