[unix-history] / usr / src / lib / libplot / hp2648 / circle.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.
 */

#ifndef lint
static char sccsid[] = "@(#)circle.c	5.1 (Berkeley) %G%";
#endif not lint

#include "hp2648.h"

circle (xc,yc,r)
int xc,yc,r;
{
	double costheta,sintheta,x,y,xn;
	int xi,yi;

	if(r<1){
		point(xc,yc);
		return;
	}
	sintheta = 1.0/r;
	costheta = pow(1-sintheta*sintheta,0.5);
	xi = x = r;
	yi = y = 0;
	do {
		point(xc+xi,yc+yi);
		xn = x;
		xi = x = x*costheta + y*sintheta;
		yi = y = y*costheta - xn*sintheta;
	} while( ! (yi==0 && xi >= r-1));
}
Commit	Line	Data
dca25f5a DF	1	/*
	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
89996944	7	#ifndef lint
dca25f5a DF	8	static char sccsid[] = "@(#)circle.c 5.1 (Berkeley) %G%";
dca25f5a DF	9	#endif not lint
89996944 RC	10
	11	#include "hp2648.h"
	12
	13	circle (xc,yc,r)
	14	int xc,yc,r;
	15	{
	16	double costheta,sintheta,x,y,xn;
	17	int xi,yi;
	18
	19	if(r<1){
	20	point(xc,yc);
	21	return;
	22	}
	23	sintheta = 1.0/r;
	24	costheta = pow(1-sintheta*sintheta,0.5);
	25	xi = x = r;
	26	yi = y = 0;
	27	do {
	28	point(xc+xi,yc+yi);
	29	xn = x;
	30	xi = x = xcostheta + ysintheta;
	31	yi = y = ycostheta - xnsintheta;
	32	} while( ! (yi==0 && xi >= r-1));
	33	}