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/* @(#)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
@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.
*/
/*
* 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
{
#ifdef _IEEE_LIBM
return __ieee754_atan2(y,x);
#else
double z;
struct exception exc;
z = __ieee754_atan2(y,x);
if(_LIB_VERSION == _IEEE_||isnan(x)||isnan(y)) return z;
if(x==0.0&&y==0.0) {
/* atan2(+-0,+-0) */
exc.arg1 = y;
exc.arg2 = x;
exc.type = DOMAIN;
exc.name = "atan2";
exc.err = 0;
exc.retval = 0.0;
if(_LIB_VERSION == _POSIX_)
errno = EDOM;
else if (!matherr(&exc)) {
errno = EDOM;
}
if (exc.err != 0)
errno = exc.err;
return exc.retval;
} else
return z;
#endif
}
#endif /* defined(_DOUBLE_IS_32BITS) */
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