/*
 * Header Begins--Do not remove################################################
 * 
 * 	C-code to compute a trochoid as in p 32 of the book
 * 
 * 	(c) Eugene Fiume, University of Toronto, 1995.
 * 
 * 	You are permitted to use this code for noncommercial, educational
 * 	purposes only.  This header must not be removed from this file.
 * 
 * Header Ends--Do not remove##################################################
 */
#include <stdio.h>
#include <math.h>

#define RADIUS  100
#define OFFSET	200
#define XRES	800
#define YRES	400
#define PI	3.141593
#define round(x) ( (int)( (x)+0.5 ) )

main(argc, argv)
	int argc;
	char *argv[];
{
	double x,y;
	int i,s,xn,yn;
	double u, r, a, du;

	printf("A Trochoid.\n\n");

	XOpen(XRES,YRES, argc, argv);

	printf("Hit a mouse button to start.\n");
	GetEvent();

	r  = RADIUS;
	a  = 25;
	du = 0.01;
	u  = 0;

	x  = 0;
	y  = RADIUS;


	/*
	 * Now let's draw the trochoid.
	 */
	while(u < 9*PI) {
		xn = round(x);
		yn = round(y);
		setpixel(xn,YRES-(OFFSET+yn),1);	/* X is upsidedown */
		u  += du;
		x  = a*u - r*sin(u);
		y  = r*cos(u);
	}

	printf("Hit a mouse button to end.\n");
	GetEvent();
}