sysdeps/libm-ieee754/s_cprojl.c

   1 /* Compute projection of complex long double value to Riemann sphere.
   2    Copyright (C) 1997 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <complex.h>
  22 #include <math.h>
  23
  24
  25 __complex__ long double
  26 __cprojl (__complex__ long double x)
  27 {
  28   __complex__ long double res;
  29
  30   if (!isfinite (__real__ x) || !isfinite (__imag__ x))
  31     {
  32       __real__ res = INFINITY;
  33       __imag__ res = __copysignl (0.0, __imag__ x);
  34     }
  35   else
  36     {
  37       long double den = (__real__ x * __real__ x + __imag__ x * __imag__ x
  38                          + 1.0);
  39
  40       __real__ res = (2.0 * __real__ x) / den;
  41       __imag__ res = (2.0 * __imag__ x) / den;
  42     }
  43
  44   return res;
  45 }
  46 weak_alias (__cprojl, cprojl)