[unix-history] / usr / src / usr.bin / f77 / libF77 / z_sqrt.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *	@(#)z_sqrt.c	5.1	%G%
 */

#include "complex"

z_sqrt(r, z)
dcomplex *r, *z;
{
double mag, sqrt(), cabs();

if( (mag = cabs(z->dreal, z->dimag)) == 0.)
	r->dreal = r->dimag = 0.;
else if(z->dreal > 0)
	{
	r->dreal = sqrt(0.5 * (mag + z->dreal) );
	r->dimag = z->dimag / r->dreal / 2;
	}
else
	{
	r->dimag = sqrt(0.5 * (mag - z->dreal) );
	if(z->dimag < 0)
		r->dimag = - r->dimag;
	r->dreal = z->dimag / r->dimag / 2;
	}
}
Commit	Line	Data
9381a6f3	1	/*
3337a9c2 RE	2	* Copyright (c) 1980 Regents of the University of California.
	3	* All rights reserved. The Berkeley software License Agreement
	4	* specifies the terms and conditions for redistribution.
	5	*
	6	* @(#)z_sqrt.c 5.1 %G%
9381a6f3 DW	7	*/
	8
	9	#include "complex"
	10
	11	z_sqrt(r, z)
	12	dcomplex r, z;
	13	{
	14	double mag, sqrt(), cabs();
	15
	16	if( (mag = cabs(z->dreal, z->dimag)) == 0.)
	17	r->dreal = r->dimag = 0.;
	18	else if(z->dreal > 0)
	19	{
	20	r->dreal = sqrt(0.5 * (mag + z->dreal) );
	21	r->dimag = z->dimag / r->dreal / 2;
	22	}
	23	else
	24	{
	25	r->dimag = sqrt(0.5 * (mag - z->dreal) );
	26	if(z->dimag < 0)
	27	r->dimag = - r->dimag;
	28	r->dreal = z->dimag / r->dimag / 2;
	29	}
	30	}