__cosdf.c raw

   1  /* origin: FreeBSD /usr/src/lib/msun/src/k_cosf.c */
   2  /*
   3   * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   4   * Debugged and optimized by Bruce D. Evans.
   5   */
   6  /*
   7   * ====================================================
   8   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9   *
  10   * Developed at SunPro, a Sun Microsystems, Inc. business.
  11   * Permission to use, copy, modify, and distribute this
  12   * software is freely granted, provided that this notice
  13   * is preserved.
  14   * ====================================================
  15   */
  16  
  17  #include "libm.h"
  18  
  19  /* |cos(x) - c(x)| < 2**-34.1 (~[-5.37e-11, 5.295e-11]). */
  20  static const double
  21  C0  = -0x1ffffffd0c5e81.0p-54, /* -0.499999997251031003120 */
  22  C1  =  0x155553e1053a42.0p-57, /*  0.0416666233237390631894 */
  23  C2  = -0x16c087e80f1e27.0p-62, /* -0.00138867637746099294692 */
  24  C3  =  0x199342e0ee5069.0p-68; /*  0.0000243904487962774090654 */
  25  
  26  float __cosdf(double x)
  27  {
  28  	double_t r, w, z;
  29  
  30  	/* Try to optimize for parallel evaluation as in __tandf.c. */
  31  	z = x*x;
  32  	w = z*z;
  33  	r = C2+z*C3;
  34  	return ((1.0+z*C0) + w*C1) + (w*z)*r;
  35  }
  36