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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [s_sine.c] - Blame information for rev 262

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1 207 jeremybenn
 
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/* @(#)z_sine.c 1.0 98/08/13 */
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/******************************************************************
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 * The following routines are coded directly from the algorithms
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 * and coefficients given in "Software Manual for the Elementary
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 * Functions" by William J. Cody, Jr. and William Waite, Prentice
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 * Hall, 1980.
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 ******************************************************************/
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/*
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FUNCTION
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        <<sin>>, <<cos>>, <<sine>>, <<sinf>>, <<cosf>>, <<sinef>>---sine or cosine
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INDEX
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sin
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INDEX
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sinf
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INDEX
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cos
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INDEX
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cosf
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ANSI_SYNOPSIS
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        #include <math.h>
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        double sin(double <[x]>);
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        float  sinf(float <[x]>);
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        double cos(double <[x]>);
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        float cosf(float <[x]>);
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TRAD_SYNOPSIS
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        #include <math.h>
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        double sin(<[x]>)
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        double <[x]>;
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        float  sinf(<[x]>)
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        float <[x]>;
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        double cos(<[x]>)
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        double <[x]>;
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        float cosf(<[x]>)
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        float <[x]>;
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DESCRIPTION
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        <<sin>> and <<cos>> compute (respectively) the sine and cosine
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        of the argument <[x]>.  Angles are specified in radians.
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RETURNS
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        The sine or cosine of <[x]> is returned.
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PORTABILITY
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        <<sin>> and <<cos>> are ANSI C.
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        <<sinf>> and <<cosf>> are extensions.
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QUICKREF
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        sin ansi pure
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        sinf - pure
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*/
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/******************************************************************
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 * sine
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 *
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 * Input:
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 *   x - floating point value
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 *   cosine - indicates cosine value
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 *
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 * Output:
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 *   Sine of x.
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 *
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 * Description:
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 *   This routine calculates sines and cosines.
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 *
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 *****************************************************************/
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#include "fdlibm.h"
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#include "zmath.h"
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#ifndef _DOUBLE_IS_32BITS
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static const double HALF_PI = 1.57079632679489661923;
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static const double ONE_OVER_PI = 0.31830988618379067154;
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static const double r[] = { -0.16666666666666665052,
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                             0.83333333333331650314e-02,
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                            -0.19841269841201840457e-03,
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                             0.27557319210152756119e-05,
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                            -0.25052106798274584544e-07,
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                             0.16058936490371589114e-09,
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                            -0.76429178068910467734e-12,
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                             0.27204790957888846175e-14 };
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double
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_DEFUN (sine, (double, int),
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        double x _AND
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        int cosine)
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{
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  int sgn, N;
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  double y, XN, g, R, res;
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  double YMAX = 210828714.0;
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  switch (numtest (x))
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    {
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      case NAN:
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        errno = EDOM;
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        return (x);
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      case INF:
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        errno = EDOM;
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        return (z_notanum.d);
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    }
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  /* Use sin and cos properties to ease computations. */
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  if (cosine)
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    {
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      sgn = 1;
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      y = fabs (x) + HALF_PI;
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    }
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  else
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    {
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      if (x < 0.0)
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        {
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          sgn = -1;
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          y = -x;
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        }
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      else
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        {
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          sgn = 1;
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          y = x;
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        }
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    }
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  /* Check for values of y that will overflow here. */
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  if (y > YMAX)
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    {
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      errno = ERANGE;
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      return (x);
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    }
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  /* Calculate the exponent. */
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  if (y < 0.0)
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    N = (int) (y * ONE_OVER_PI - 0.5);
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  else
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    N = (int) (y * ONE_OVER_PI + 0.5);
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  XN = (double) N;
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  if (N & 1)
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    sgn = -sgn;
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  if (cosine)
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    XN -= 0.5;
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  y = fabs (x) - XN * __PI;
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  if (-z_rooteps < y && y < z_rooteps)
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    res = y;
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  else
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    {
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      g = y * y;
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      /* Calculate the Taylor series. */
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      R = (((((((r[6] * g + r[5]) * g + r[4]) * g + r[3]) * g + r[2]) * g + r[1]) * g + r[0]) * g);
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      /* Finally, compute the result. */
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      res = y + y * R;
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    }
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  res *= sgn;
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  return (res);
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}
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#endif /* _DOUBLE_IS_32BITS */

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