c_div.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static char	*sccsid = " @(#)c_div.c	1.2	(ULTRIX)	1/16/86";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1986 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/************************************************************************
*
*			Modification History
*
*	David Metsky		10-Jan-86
*
* 001	Replaced old version with BSD 4.3 version as part of upgrade.
*
*	Based on:	c_div.c		5.1	6/7/85
*
*************************************************************************/

#include "complex"
#include <stdio.h>
#include <errno.h>

c_div(c, a, b)
complex *a, *b, *c;
{
double ratio, den;
double abr, abi;

if( (abr = b->real) < 0.)
	abr = - abr;
if( (abi = b->imag) < 0.)
	abi = - abi;
if( abr <= abi )
	{
	if(abi == 0) {
		fprintf(stderr,"complex division by zero\n");
		f77_abort(EDOM);
	}
	ratio = b->real / b->imag ;
	den = b->imag * (1 + ratio*ratio);
	c->real = (a->real*ratio + a->imag) / den;
	c->imag = (a->imag*ratio - a->real) / den;
	}

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

}