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