[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	5.2	%G%
 */

#include "complex"
#ifdef tahoe
#include <tahoemath/FP.h>
#define cabs zabs
#endif tahoe

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)
#ifndef tahoe
		r->dimag = - r->dimag;
#else tahoe
		*((long int *)&r->dimag) ^= SIGN_BIT;
#endif tahoe
	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	*
0ab3343e	6	* @(#)z_sqrt.c 5.2 %G%
9381a6f3 DW	7	*/
	8
	9	#include "complex"
0ab3343e KM	10	#ifdef tahoe
	11	#include <tahoemath/FP.h>
	12	#define cabs zabs
	13	#endif tahoe
9381a6f3 DW	14
	15	z_sqrt(r, z)
	16	dcomplex r, z;
	17	{
	18	double mag, sqrt(), cabs();
	19
	20	if( (mag = cabs(z->dreal, z->dimag)) == 0.)
	21	r->dreal = r->dimag = 0.;
	22	else if(z->dreal > 0)
	23	{
	24	r->dreal = sqrt(0.5 * (mag + z->dreal) );
	25	r->dimag = z->dimag / r->dreal / 2;
	26	}
	27	else
	28	{
	29	r->dimag = sqrt(0.5 * (mag - z->dreal) );
	30	if(z->dimag < 0)
0ab3343e	31	#ifndef tahoe
9381a6f3	32	r->dimag = - r->dimag;
0ab3343e KM	33	#else tahoe
	34	((long int )&r->dimag) ^= SIGN_BIT;
	35	#endif tahoe
9381a6f3 DW	36	r->dreal = z->dimag / r->dimag / 2;
	37	}
	38	}