91 lines
1.7 KiB
C
91 lines
1.7 KiB
C
|
|
||
|
|
/* @(#)w_atan2.c 5.1 93/09/24 */
|
||
|
|
/*
|
||
|
|
* ====================================================
|
||
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
||
|
|
*
|
||
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
||
|
|
* Permission to use, copy, modify, and distribute this
|
||
|
|
* software is freely granted, provided that this notice
|
||
|
|
* is preserved.
|
||
|
|
* ====================================================
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
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
|
||
|
|
|
||
|
|
You can modify error handling for these functions using <<matherr>>.
|
||
|
|
|
||
|
|
PORTABILITY
|
||
|
|
<<atan2>> is ANSI C. <<atan2f>> is an extension.
|
||
|
|
|
||
|
|
|
||
|
|
*/
|
||
|
|
|
||
|
|
/*
|
||
|
|
* wrapper atan2(y,x)
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "fdlibm.h"
|
||
|
|
#include <errno.h>
|
||
|
|
|
||
|
|
#ifndef _DOUBLE_IS_32BITS
|
||
|
|
|
||
|
|
#ifdef __STDC__
|
||
|
|
double atan2(double y, double x) /* wrapper atan2 */
|
||
|
|
#else
|
||
|
|
double atan2(y,x) /* wrapper atan2 */
|
||
|
|
double y,x;
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
return __ieee754_atan2(y,x);
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* defined(_DOUBLE_IS_32BITS) */
|