libquadmath/math/casinhq.c

   1 /* Return arc hyperbole sine for __float128 value.
   2    Copyright (C) 1997, 1998 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 "quadmath-imp.h"
  22
  23
  24 __complex128
  25 casinhq (__complex128 x)
  26 {
  27   __complex128 res;
  28   int rcls = fpclassifyq (__real__ x);
  29   int icls = fpclassifyq (__imag__ x);
  30
  31   if (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE)
  32     {
  33       if (icls == QUADFP_INFINITE)
  34         {
  35           __real__ res = copysignq (HUGE_VALQ, __real__ x);
  36
  37           if (rcls == QUADFP_NAN)
  38             __imag__ res = nanq ("");
  39           else
  40             __imag__ res = copysignq (rcls >= QUADFP_ZERO ? M_PI_2q : M_PI_4q,
  41                                       __imag__ x);
  42         }
  43       else if (rcls <= QUADFP_INFINITE)
  44         {
  45           __real__ res = __real__ x;
  46           if ((rcls == QUADFP_INFINITE && icls >= QUADFP_ZERO)
  47               || (rcls == QUADFP_NAN && icls == QUADFP_ZERO))
  48             __imag__ res = copysignq (0.0, __imag__ x);
  49           else
  50             __imag__ res = nanq ("");
  51         }
  52       else
  53         {
  54           __real__ res = nanq ("");
  55           __imag__ res = nanq ("");
  56         }
  57     }
  58   else if (rcls == QUADFP_ZERO && icls == QUADFP_ZERO)
  59     {
  60       res = x;
  61     }
  62   else
  63     {
  64       __complex128 y;
  65
  66       __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) + 1.0;
  67       __imag__ y = 2.0 * __real__ x * __imag__ x;
  68
  69       y = csqrtq (y);
  70
  71       __real__ y += __real__ x;
  72       __imag__ y += __imag__ x;
  73
  74       res = clogq (y);
  75
  76       /* Ensure zeros have correct sign and results are correct if
  77          very close to branch cuts.  */
  78       __real__ res = copysignq (__real__ res, __real__ x);
  79       __imag__ res = copysignq (__imag__ res, __imag__ x);
  80     }
  81
  82   return res;
  83 }