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  1. /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
  2. /* k_cosf.c -- float version of k_cos.c
  3.  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
  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. #if defined(LIBM_SCCS) && !defined(lint)
  18. static char rcsid[] = "$Id: k_cosf.c,v 1.2 1994/08/18 23:06:10 jtc Exp $";
  19. #endif
  20.  
  21. #include "math.h"
  22. #include "math_private.h"
  23.  
  24. #ifdef __STDC__
  25. static const float
  26. #else
  27. static float
  28. #endif
  29. one =  1.0000000000e+00, /* 0x3f800000 */
  30. C1  =  4.1666667908e-02, /* 0x3d2aaaab */
  31. C2  = -1.3888889225e-03, /* 0xbab60b61 */
  32. C3  =  2.4801587642e-05, /* 0x37d00d01 */
  33. C4  = -2.7557314297e-07, /* 0xb493f27c */
  34. C5  =  2.0875723372e-09, /* 0x310f74f6 */
  35. C6  = -1.1359647598e-11; /* 0xad47d74e */
  36.  
  37. #ifdef __STDC__
  38.         float __kernel_cosf(float x, float y)
  39. #else
  40.         float __kernel_cosf(x, y)
  41.         float x,y;
  42. #endif
  43. {
  44.         float a,hz,z,r,qx;
  45.         int32_t ix;
  46.         GET_FLOAT_WORD(ix,x);
  47.         ix &= 0x7fffffff;                       /* ix = |x|'s high word*/
  48.         if(ix<0x32000000) {                     /* if x < 2**27 */
  49.             if(((int)x)==0) return one;         /* generate inexact */
  50.         }
  51.         z  = x*x;
  52.         r  = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*C6)))));
  53.         if(ix < 0x3e99999a)                     /* if |x| < 0.3 */
  54.             return one - ((float)0.5*z - (z*r - x*y));
  55.         else {
  56.             if(ix > 0x3f480000) {               /* x > 0.78125 */
  57.                 qx = (float)0.28125;
  58.             } else {
  59.                 SET_FLOAT_WORD(qx,ix-0x01000000);       /* x/4 */
  60.             }
  61.             hz = (float)0.5*z-qx;
  62.             a  = one-qx;
  63.             return a - (hz - (z*r-x*y));
  64.         }
  65. }
  66.