sysdeps/libm-ieee754/s_sincos.c

   1 /* Compute sine and cosine of argument.
   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 <math.h>
  22
  23 #include "math_private.h"
  24
  25
  26 void
  27 __sincos (double x, double *sinx, double *cosx)
  28 {
  29   int32_t ix;
  30
  31   /* High word of x. */
  32   GET_HIGH_WORD (ix, x);
  33
  34   /* |x| ~< pi/4 */
  35   ix &= 0x7fffffff;
  36   if (ix <= 0x3fe921fb)
  37     {
  38       *sinx = __kernel_sin (x, 0.0, 0);
  39       *cosx = __kernel_cos (x, 0.0);
  40     }
  41   else if (ix>=0x7ff00000)
  42     {
  43       /* sin(Inf or NaN) is NaN */
  44       *sinx = *cosx = x - x;
  45     }
  46   else
  47     {
  48       /* Argument reduction needed.  */
  49       double y[2];
  50       int n;
  51
  52       n = __ieee754_rem_pio2 (x, y);
  53       switch (n & 3)
  54         {
  55         case 0:
  56           *sinx = __kernel_sin (y[0], y[1], 1);
  57           *cosx = __kernel_cos (y[0], y[1]);
  58           break;
  59         case 1:
  60           *sinx = __kernel_cos (y[0], y[1]);
  61           *cosx = -__kernel_sin (y[0], y[1], 1);
  62           break;
  63         case 2:
  64           *sinx = -__kernel_sin (y[0], y[1], 1);
  65           *cosx = -__kernel_cos (y[0], y[1]);
  66           break;
  67         default:
  68           *sinx = -__kernel_cos (y[0], y[1]);
  69           *cosx = __kernel_sin (y[0], y[1], 1);
  70           break;
  71         }
  72     }
  73 }
  74 weak_alias (__sincos, sincos)
  75 #ifdef NO_LONG_DOUBLE
  76 strong_alias (__sincos, __sincosl)
  77 weak_alias (__sincos, sincosl)
  78 #endif