mirror of
https://github.com/autc04/Retro68.git
synced 2024-12-01 11:52:47 +00:00
105 lines
2.1 KiB
C
105 lines
2.1 KiB
C
|
|
/* @(#)z_asinef.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.
|
|
******************************************************************/
|
|
/******************************************************************
|
|
* Arcsine
|
|
*
|
|
* Input:
|
|
* x - floating point value
|
|
* acosine - indicates acos calculation
|
|
*
|
|
* Output:
|
|
* Arcsine of x.
|
|
*
|
|
* Description:
|
|
* This routine calculates arcsine / arccosine.
|
|
*
|
|
*****************************************************************/
|
|
|
|
#include "fdlibm.h"
|
|
#include "zmath.h"
|
|
|
|
static const float p[] = { 0.933935835, -0.504400557 };
|
|
static const float q[] = { 0.560363004e+1, -0.554846723e+1 };
|
|
static const float a[] = { 0.0, 0.785398163 };
|
|
static const float b[] = { 1.570796326, 0.785398163 };
|
|
|
|
float
|
|
asinef (float x,
|
|
int acosine)
|
|
{
|
|
int flag, i;
|
|
int branch = 0;
|
|
float g, res, R, P, Q, y;
|
|
|
|
/* Check for special values. */
|
|
i = numtestf (x);
|
|
if (i == NAN || i == INF)
|
|
{
|
|
errno = EDOM;
|
|
if (i == NAN)
|
|
return (x);
|
|
else
|
|
return (z_infinity_f.f);
|
|
}
|
|
|
|
y = fabsf (x);
|
|
flag = acosine;
|
|
|
|
if (y > 0.5)
|
|
{
|
|
i = 1 - flag;
|
|
|
|
/* Check for range error. */
|
|
if (y > 1.0)
|
|
{
|
|
errno = ERANGE;
|
|
return (z_notanum_f.f);
|
|
}
|
|
|
|
g = (1 - y) / 2.0;
|
|
y = -2 * sqrt (g);
|
|
branch = 1;
|
|
}
|
|
else
|
|
{
|
|
i = flag;
|
|
if (y < z_rooteps_f)
|
|
res = y;
|
|
else
|
|
g = y * y;
|
|
}
|
|
|
|
if (y >= z_rooteps_f || branch == 1)
|
|
{
|
|
/* Calculate the Taylor series. */
|
|
P = (p[1] * g + p[0]) * g;
|
|
Q = (g + q[1]) * g + q[0];
|
|
R = P / Q;
|
|
|
|
res = y + y * R;
|
|
}
|
|
|
|
/* Calculate asine or acose. */
|
|
if (flag == 0)
|
|
{
|
|
res = (a[i] + res) + a[i];
|
|
if (x < 0.0)
|
|
res = -res;
|
|
}
|
|
else
|
|
{
|
|
if (x < 0.0)
|
|
res = (b[i] + res) + b[i];
|
|
else
|
|
res = (a[i] - res) + a[i];
|
|
}
|
|
|
|
return (res);
|
|
}
|