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  1. /* kf_cos.c -- float version of k_cos.c
  2.  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
  3.  */
  4.  
  5. /*
  6.  * ====================================================
  7.  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  8.  *
  9.  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10.  * Permission to use, copy, modify, and distribute this
  11.  * software is freely granted, provided that this notice
  12.  * is preserved.
  13.  * ====================================================
  14.  */
  15.  
  16. #include "fdlibm.h"
  17.  
  18. #ifdef __STDC__
  19. static const float
  20. #else
  21. static float
  22. #endif
  23. one =  1.0000000000e+00, /* 0x3f800000 */
  24. C1  =  4.1666667908e-02, /* 0x3d2aaaab */
  25. C2  = -1.3888889225e-03, /* 0xbab60b61 */
  26. C3  =  2.4801587642e-05, /* 0x37d00d01 */
  27. C4  = -2.7557314297e-07, /* 0xb493f27c */
  28. C5  =  2.0875723372e-09, /* 0x310f74f6 */
  29. C6  = -1.1359647598e-11; /* 0xad47d74e */
  30.  
  31. #ifdef __STDC__
  32.         float __kernel_cosf(float x, float y)
  33. #else
  34.         float __kernel_cosf(x, y)
  35.         float x,y;
  36. #endif
  37. {
  38.         float a,hz,z,r,qx;
  39.         __int32_t ix;
  40.         GET_FLOAT_WORD(ix,x);
  41.         ix &= 0x7fffffff;                       /* ix = |x|'s high word*/
  42.         if(ix<0x32000000) {                     /* if x < 2**27 */
  43.             if(((int)x)==0) return one;         /* generate inexact */
  44.         }
  45.         z  = x*x;
  46.         r  = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*C6)))));
  47.         if(ix < 0x3e99999a)                     /* if |x| < 0.3 */
  48.             return one - ((float)0.5*z - (z*r - x*y));
  49.         else {
  50.             if(ix > 0x3f480000) {               /* x > 0.78125 */
  51.                 qx = (float)0.28125;
  52.             } else {
  53.                 SET_FLOAT_WORD(qx,ix-0x01000000);       /* x/4 */
  54.             }
  55.             hz = (float)0.5*z-qx;
  56.             a  = one-qx;
  57.             return a - (hz - (z*r-x*y));
  58.         }
  59. }
  60.