90 lines
1.6 KiB
C
90 lines
1.6 KiB
C
|
|
/* @(#)z_atan2.c 1.0 98/08/13 */
|
|
|
|
/*
|
|
FUNCTION
|
|
<<atan2>>, <<atan2f>>---arc tangent of y/x
|
|
|
|
INDEX
|
|
atan2
|
|
INDEX
|
|
atan2f
|
|
|
|
ANSI_SYNOPSIS
|
|
#include <math.h>
|
|
double atan2(double <[y]>,double <[x]>);
|
|
float atan2f(float <[y]>,float <[x]>);
|
|
|
|
TRAD_SYNOPSIS
|
|
#include <math.h>
|
|
double atan2(<[y]>,<[x]>);
|
|
double <[y]>;
|
|
double <[x]>;
|
|
|
|
float atan2f(<[y]>,<[x]>);
|
|
float <[y]>;
|
|
float <[x]>;
|
|
|
|
DESCRIPTION
|
|
|
|
<<atan2>> computes the inverse tangent (arc tangent) of <[y]>/<[x]>.
|
|
<<atan2>> produces the correct result even for angles near
|
|
@ifnottex
|
|
pi/2 or -pi/2
|
|
@end ifnottex
|
|
@tex
|
|
$\pi/2$ or $-\pi/2$
|
|
@end tex
|
|
(that is, when <[x]> is near 0).
|
|
|
|
<<atan2f>> is identical to <<atan2>>, save that it takes and returns
|
|
<<float>>.
|
|
|
|
RETURNS
|
|
<<atan2>> and <<atan2f>> return a value in radians, in the range of
|
|
@ifnottex
|
|
-pi to pi.
|
|
@end ifnottex
|
|
@tex
|
|
$-\pi$ to $\pi$.
|
|
@end tex
|
|
|
|
If both <[x]> and <[y]> are 0.0, <<atan2>> causes a <<DOMAIN>> error.
|
|
|
|
You can modify error handling for these functions using <<matherr>>.
|
|
|
|
PORTABILITY
|
|
<<atan2>> is ANSI C. <<atan2f>> is an extension.
|
|
|
|
|
|
*/
|
|
|
|
/******************************************************************
|
|
* Arctangent2
|
|
*
|
|
* Input:
|
|
* v, u - floating point values
|
|
*
|
|
* Output:
|
|
* arctan2 of v / u
|
|
*
|
|
* Description:
|
|
* This routine returns the arctan2 of v / u.
|
|
*
|
|
*****************************************************************/
|
|
|
|
#include "fdlibm.h"
|
|
#include "zmath.h"
|
|
|
|
#ifndef _DOUBLE_IS_32BITS
|
|
|
|
double
|
|
_DEFUN (atan2, (double, double),
|
|
double v _AND
|
|
double u)
|
|
{
|
|
return (atangent (0.0, v, u, 1));
|
|
}
|
|
|
|
#endif /* _DOUBLE_IS_32BITS */
|