Mandelbrot Algorithm

mandelbrot.js

let canvas = document.getElementById('universe').getContext('2d')
let atom = (x,y,c) => {canvas.fillStyle = c; canvas.fillRect(x,y,3,3)};
window.CP.PenTimer.MAX_TIME_IN_LOOP_WO_EXIT = 10000;

for (y=1; y < 1000; y++) {
    for (x=1; x < 1000; x++) {
        
        dx = (x-500)/200
        dy = (y-500)/200
        a = dx
        b = dy
        
        for (t = 1; t < 200; t++) {
            d = (a*a) - (b*b) + dx
            b = 2*(a*b) + dy
            a = d
            H = d > 200
            if (H) {
                atom(x,y, 'rgb('+t*5+','+t*2+','+ t*0.9 +')');
                break;
            }
        }
    }
}