src/math/__sindf.c

   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 }