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Atari Mega Archive 1
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src6.zoo
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casin.c
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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
*
* casin complex double precision arc sine
*
* KEY WORDS
*
* casin
* machine independent routines
* complex functions
* math libraries
*
* DESCRIPTION
*
* Computes double precision complex arc sine of
* a double precision complex argument.
*
* USAGE
*
* COMPLEX casin (z)
* COMPLEX z;
*
* PROGRAMMER
*
* Fred Fish
* Tempe, Az 85281
* (602) 966-8871
*
* INTERNALS
*
* Computes complex arc sine of z = x + j y from:
*
* casin(z) = -j * clog(csqrt(1-z*z) + j*z)
*
*/
#include <stdio.h>
#include <pmluser.h>
#include "pml.h"
COMPLEX casin (z)
COMPLEX z;
{
COMPLEX temp;
extern COMPLEX csqrt (), clog (), cmult ();
temp = cmult (z, z);
temp.real = 1.0 - temp.real;
temp.imag = -temp.imag;
temp = csqrt (temp);
temp.real -= z.imag;
temp.imag += z.real;
temp = clog (temp);
z.real = temp.imag;
z.imag = -temp.real;
return (z);
}