begin
comment PointOnLine procedure: is point on line?;
	record RPoint (real x, y);
	record RLine (real a, b, c);

	logical procedure PointOnLine(reference(RPoint) value point; reference(RLine) value line );
	begin
		real d;
		d := a(line) + b(line)*x(point) + c(line)*y(point);
		write(d);
		abs(d) < 0.000001
	end;
	
	reference(RPoint) pt;
	reference(RLine) lin;
	boolean res;

	pt := RPoint( 1, 1);
	lin := RLine(1.0, 2.0, -3.0);
	
	res := PointOnLine(pt, lin);
	write(res);
	
	pt := RPoint( 1, 3);
	res := PointOnLine(pt, lin);
	write(res);
	
end.