Mildly modified from some Mandelbrot site.

gistfile1.txt

Mandelbrot

Convert to Ruby syntax.

Stretch goals if time:

parallelize computation
Use Complex
play with richer RGB
change ZOOM

MandelBrot.java

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
 
public class Mandelbrot extends JFrame {
    private final int MAX_ITER = 570;
    private final double ZOOM = 150;
    private BufferedImage image;
 
    public Mandelbrot() {
        super("Mandelbrot Set");
        setBounds(100, 100, 800, 600);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
        for (int y = 0; y < getHeight(); y++) {
            for (int x = 0; x < getWidth(); x++) {
                double zx = 0;
                double zy = 0;
                double cX = (x - 400) / ZOOM;
                double cY = (y - 300) / ZOOM;
                int iter = MAX_ITER;
                while (zx * zx + zy * zy < 4 && iter > 0) {
                    double tmp = zx * zx - zy * zy + cX;
                    zy = 2.0 * zx * zy + cY;
                    zx = tmp;
                    iter--;
                }
                image.setRGB(x, y, iter | (iter << 8));
            }
        }
    }
 
    @Override
    public void paint(Graphics g) {
        g.drawImage(image, 0, 0, this);
    }
 
    public static void main(String[] args) {
        new Mandelbrot().setVisible(true);
    }
}