__sindf.c raw

   1  /* origin: FreeBSD /usr/src/lib/msun/src/k_sinf.c */
   2  /*
   3   * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   4   * 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  /* |sin(x)/x - s(x)| < 2**-37.5 (~[-4.89e-12, 4.824e-12]). */
  20  static const double
  21  S1 = -0x15555554cbac77.0p-55, /* -0.166666666416265235595 */
  22  S2 =  0x111110896efbb2.0p-59, /*  0.0083333293858894631756 */
  23  S3 = -0x1a00f9e2cae774.0p-65, /* -0.000198393348360966317347 */
  24  S4 =  0x16cd878c3b46a7.0p-71; /*  0.0000027183114939898219064 */
  25  
  26  float __sindf(double x)
  27  {
  28  	double_t r, s, w, z;
  29  
  30  	/* Try to optimize for parallel evaluation as in __tandf.c. */
  31  	z = x*x;
  32  	w = z*z;
  33  	r = S3 + z*S4;
  34  	s = z*x;
  35  	return (x + s*(S1 + z*S2)) + s*w*r;
  36  }
  37