modules/fdlibm/src/k_cosf.cpp

   1 /* k_cosf.c -- float version of k_cos.c
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  * Debugged and optimized by Bruce D. Evans.
   4  */
   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 #ifndef INLINE_KERNEL_COSDF
  18 //#include <sys/cdefs.h>
  19 //__FBSDID("$FreeBSD$");
  20 #endif
  21
  22 #include "math_private.h"
  23
  24 /* |cos(x) - c(x)| < 2**-34.1 (~[-5.37e-11, 5.295e-11]). */
  25 static const double
  26 one =  1.0,
  27 C0  = -0x1ffffffd0c5e81.0p-54,  /* -0.499999997251031003120 */
  28 C1  =  0x155553e1053a42.0p-57,  /*  0.0416666233237390631894 */
  29 C2  = -0x16c087e80f1e27.0p-62,  /* -0.00138867637746099294692 */
  30 C3  =  0x199342e0ee5069.0p-68;  /*  0.0000243904487962774090654 */
  31
  32 #ifdef INLINE_KERNEL_COSDF
  33 static __inline
  34 #endif
  35 float
  36 __kernel_cosdf(double x)
  37 {
  38         double r, w, z;
  39
  40         /* Try to optimize for parallel evaluation as in k_tanf.c. */
  41         z = x*x;
  42         w = z*z;
  43         r = C2+z*C3;
  44         return ((one+z*C0) + w*C1) + (w*z)*r;
  45 }