Ultrix-3.1/src/libF77/z_div.c

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/**********************************************************************
 *   Copyright (c) Digital Equipment Corporation 1984, 1985, 1986.    *
 *   All Rights Reserved. 					      *
 *   Reference "/usr/src/COPYRIGHT" for applicable restrictions.      *
 **********************************************************************/

/*
 * SCCSID: @(#)z_div.c	3.0	4/22/86
 */
struct dcomplex { double dreal, dimag; };

z_div(c, a, b)
struct dcomplex *a, *b, *c;
{
double ratio, den;
double abr, abi;

if( (abr = b->dreal) < 0.)
	abr = - abr;
if( (abi = b->dimag) < 0.)
	abi = - abi;
if( abr <= abi )
	{
	if(abi == 0)
		abort(); /* fatal("complex division by zero"); */
	ratio = b->dreal / b->dimag ;
	den = b->dimag * (1 + ratio*ratio);
	c->dreal = (a->dreal*ratio + a->dimag) / den;
	c->dimag = (a->dimag*ratio - a->dreal) / den;
	}

else
	{
	ratio = b->dimag / b->dreal ;
	den = b->dreal * (1 + ratio*ratio);
	c->dreal = (a->dreal + a->dimag*ratio) / den;
	c->dimag = (a->dimag - a->dreal*ratio) / den;
	}

}