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Atari Mega Archive 1
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src6.zoo
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catan.c
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C/C++ Source or Header
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1991-09-24
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/************************************************************************
* *
* N O T I C E *
* *
* Copyright Abandoned, 1987, Fred Fish *
* *
* This previously copyrighted work has been placed into the *
* public domain by the author (Fred Fish) and may be freely used *
* for any purpose, private or commercial. I would appreciate *
* it, as a courtesy, if this notice is left in all copies and *
* derivative works. Thank you, and enjoy... *
* *
* The author makes no warranty of any kind with respect to this *
* product and explicitly disclaims any implied warranties of *
* merchantability or fitness for any particular purpose. *
* *
************************************************************************
*/
/*
* FUNCTION
*
* catan complex double precision arc tangent
*
* KEY WORDS
*
* catan
* machine independent routines
* complex functions
* math libraries
*
* DESCRIPTION
*
* Computes double precision complex arc tangent of
* a double precision complex argument.
*
* USAGE
*
* COMPLEX catan (z)
* COMPLEX z;
*
* PROGRAMMER
*
* Fred Fish
* Tempe, Az 85281
* (602) 966-8871
*
* INTERNALS
*
* Computes complex arc tangent of z = x + j y from:
*
* catan(z) = -j/2 * clog( (j+z) / (j-z) )
*
*/
#include <stdio.h>
#include <pmluser.h>
#include "pml.h"
COMPLEX catan (z)
COMPLEX z;
{
COMPLEX temp;
double swaptemp;
extern COMPLEX cdiv (), clog ();
temp.real = -z.real;
temp.imag = 1.0 - z.imag;
z.imag += 1.0;
z = cdiv (z, temp);
z = clog (z);
swaptemp = z.real;
z.real = -0.5 * z.imag;
z.imag = 0.5 * swaptemp;
return (z);
}