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154 lines
3.2 KiB
C
154 lines
3.2 KiB
C
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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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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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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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sine (double x,
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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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