mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-27 14:50:23 +00:00
113 lines
2.2 KiB
C
113 lines
2.2 KiB
C
|
|
/* @(#)z_sinef.c 1.0 98/08/13 */
|
|
/******************************************************************
|
|
* The following routines are coded directly from the algorithms
|
|
* and coefficients given in "Software Manual for the Elementary
|
|
* Functions" by William J. Cody, Jr. and William Waite, Prentice
|
|
* Hall, 1980.
|
|
******************************************************************/
|
|
/******************************************************************
|
|
* sine generator
|
|
*
|
|
* Input:
|
|
* x - floating point value
|
|
* cosine - indicates cosine value
|
|
*
|
|
* Output:
|
|
* Sine of x.
|
|
*
|
|
* Description:
|
|
* This routine calculates sines and cosines.
|
|
*
|
|
*****************************************************************/
|
|
|
|
#include "fdlibm.h"
|
|
#include "zmath.h"
|
|
|
|
static const float HALF_PI = 1.570796326;
|
|
static const float ONE_OVER_PI = 0.318309886;
|
|
static const float r[] = { -0.1666665668,
|
|
0.8333025139e-02,
|
|
-0.1980741872e-03,
|
|
0.2601903036e-5 };
|
|
|
|
float
|
|
_DEFUN (sinef, (float, int),
|
|
float x _AND
|
|
int cosine)
|
|
{
|
|
int sgn, N;
|
|
float y, XN, g, R, res;
|
|
float YMAX = 210828714.0;
|
|
|
|
switch (numtestf (x))
|
|
{
|
|
case NAN:
|
|
errno = EDOM;
|
|
return (x);
|
|
case INF:
|
|
errno = EDOM;
|
|
return (z_notanum_f.f);
|
|
}
|
|
|
|
/* Use sin and cos properties to ease computations. */
|
|
if (cosine)
|
|
{
|
|
sgn = 1;
|
|
y = fabsf (x) + HALF_PI;
|
|
}
|
|
else
|
|
{
|
|
if (x < 0.0)
|
|
{
|
|
sgn = -1;
|
|
y = -x;
|
|
}
|
|
else
|
|
{
|
|
sgn = 1;
|
|
y = x;
|
|
}
|
|
}
|
|
|
|
/* Check for values of y that will overflow here. */
|
|
if (y > YMAX)
|
|
{
|
|
errno = ERANGE;
|
|
return (x);
|
|
}
|
|
|
|
/* Calculate the exponent. */
|
|
if (y < 0.0)
|
|
N = (int) (y * ONE_OVER_PI - 0.5);
|
|
else
|
|
N = (int) (y * ONE_OVER_PI + 0.5);
|
|
XN = (float) N;
|
|
|
|
if (N & 1)
|
|
sgn = -sgn;
|
|
|
|
if (cosine)
|
|
XN -= 0.5;
|
|
|
|
y = fabsf (x) - XN * __PI;
|
|
|
|
if (-z_rooteps_f < y && y < z_rooteps_f)
|
|
res = y;
|
|
|
|
else
|
|
{
|
|
g = y * y;
|
|
|
|
/* Calculate the Taylor series. */
|
|
R = (((r[3] * g + r[2]) * g + r[1]) * g + r[0]) * g;
|
|
|
|
/* Finally, compute the result. */
|
|
res = y + y * R;
|
|
}
|
|
|
|
res *= sgn;
|
|
|
|
return (res);
|
|
}
|