extern float sin(),cos(),exp();
int contrl[12], intin[256], ptsin[256], intout[256], ptsout[256];
float x, y, dfy, py, f;
float pi,SIN_THETA,COS_THETA;
int width,xcount,ycount;
int top[1000],bottom[1000];
int handle,height,i,dummy;
int oldx,oldy;
int NUM_LINES;
int pxy[4];

#define TRUE 1
#define FALSE 0

float func()
{
return(cos((x*x+y*y)*5.)*exp(-x*x-y*y));
}

float scalex()
{
float temp;
temp=width/2.;
return((xcount-temp)/width*pi);
}

float scaley()
{
float temp;
temp=NUM_LINES/2.;
return((temp-ycount)/NUM_LINES*pi);
}

unscaley()
{
return((dfy+2.)/4.*height);
}



main()
{
register visible, dy;

/* The following is the setup to use the VDI and AES */

/* Set the system up to do GEM calls*/

  appl_init();

/* Get the handle of the desktop */

handle=graf_handle(&width,&height,&dummy,&dummy);

  /* Open the workstation. */

  for (i=1; i<10; ++i) intin[i] = i;
  intin[10] = 2;

  v_opnvwk(intin, &handle, intout);

  graf_mouse(256,pxy);

	width=intout[0];
	height=intout[1];
	vswr_mode(handle,2);
	v_clrwk(handle);
	oldx=0;
	oldy=0;
	NUM_LINES=64;
	SIN_THETA=.5;
	COS_THETA=0.866;
	pi=3.14159;

	for (ycount=0; ycount<NUM_LINES; ++ycount) {
		y=scaley();
		py=y*SIN_THETA;
		for (xcount=0; xcount<(width+1); ++xcount) {
			x=scalex();
			f=func();
			dfy=py-f*COS_THETA;
			dy=unscale();
			if (xcount==0)
				visible=FALSE;
			else if (ycount==0) {
				top[xcount]=dy;
				bottom[xcount]=dy;
				visible=TRUE; }
			else {	visible=TRUE;
				if (top[xcount]<dy)
					top[xcount]=dy;
				else if (bottom[xcount]>dy)
					bottom[xcount]=dy;
				else
					visible=FALSE; }
			if (visible==TRUE) {
				vsl_color(handle,1);
				pxy[0]=oldx;
				pxy[1]=oldy;
				pxy[2]=xcount;
				pxy[3]=dy;
				v_pline(handle,2,pxy); }
			oldx=xcount;
			oldy=dy;
		}
	}
evnt_keybd();
}
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