function f(x) {
    return (Math.sin(x)*Math.cos(2*x))    ;
}
var zoom=20
var amp=20
function update(){
    zoom=mouseX/10
    amp=mouseY/10
}
function draw() {
    for(i=-100;i<400;i=i+0.009){ //800 is the max horizontal screen size
        //point is the value of the var
        point= -(f(i))*zoom*amp;
        context.fillRect(i*zoom+400,point+300,1,1);
    }
};