Below is the syntax highlighted version of NewtonChaos.java
from §3.2 Creating Data Types.
/****************************************************************************** * Compilation: javac NewtonChaos.java * Execution: java NewtonChaos n * Dependencies: Picture.java Complex.java * * Plot an n-by-n grid of points showing which of the four roots * that Newton's method converges to in the 2-by-2 box centered at (0, 0). * ******************************************************************************/ import java.awt.Color; public class NewtonChaos { // return number of Mandelbrot iterations to check z = x + iy static Color newton(Complex z) { double EPSILON = 0.00000001; Complex four = new Complex(4, 0); Complex one = new Complex(1, 0); Complex root1 = new Complex(1, 0); Complex root2 = new Complex(-1, 0); Complex root3 = new Complex(0, 1); Complex root4 = new Complex(0, -1); for (int i = 0; i < 100; i++) { Complex f = z.times(z).times(z).times(z).minus(one); Complex fp = four.times(z).times(z).times(z); z = z.minus(f.divides(fp)); if (z.minus(root1).abs() <= EPSILON) return Color.WHITE; if (z.minus(root2).abs() <= EPSILON) return Color.RED; if (z.minus(root3).abs() <= EPSILON) return Color.GREEN; if (z.minus(root4).abs() <= EPSILON) return Color.BLUE; } return Color.BLACK; } public static void main(String[] args) { int n = Integer.parseInt(args[0]); double xmin = -1.0; double ymin = -1.0; double width = 2.0; double height = 2.0; Picture picture = new Picture(n, n); for (int col = 0; col < n; col++) { for (int row = 0; row < n; row++) { double x = xmin + col * width / n; double y = ymin + row * height / n; Complex z = new Complex(x, y); Color color = newton(z); picture.set(col, n - 1 - row, color); } } picture.show(); } }