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/* @(#)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
@ifinfo
pi/2 or -pi/2
@end ifinfo
@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
@ifinfo
-pi to pi.
@end ifinfo
@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 */
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