function cube(x){
	return x*x*x;
}

function diff(f){
	return function(x){
		return (f(x+0.000001)-f(x))/0.000001;
	}
}

for(x=-4;x<=4;x=x+0.4){
	y=diff(cube)(x);
	Println(x+" --> "+y);
}