// 2D Fractal Mountain,  Evgeny Demidov,  8 Feb 2002
  import java.awt.*;
  import java.awt.event.*;
  public class applet-math-fract2D extends java.applet.Applet
   implements ActionListener, KeyListener{
    int  n = 256, n1, w, h, h2, h0, lbSize = 50;
    double p[], m = 2;
    Label lbM;    Button btNew;    TextField tfM;
  
  public void init() {
    w = getSize().width;
    h = getSize().height - lbSize;  h2 = h/2; h0 = h2 + lbSize;
    String s=getParameter("n"); if (s != null) n = Integer.parseInt(s);
    s=getParameter("m"); if (s != null) m = Double.valueOf(s).doubleValue();
    n1 = n+1;
    p = new double[n1];
    lbM = new Label("m", Label.RIGHT);  add(lbM);
    tfM = new TextField( "" + (float)m, 5);  add(tfM);
    tfM.addKeyListener(this);
    btNew = new Button("New");   btNew.addActionListener(this);
    add(btNew);
    build();
  }
  public void build(){
    double R = 2;
    int k = n/2;
    p[k] = R*(Math.random()-.5);
    while( k > 1){
      int st = k;
      k /= 2;  R /= m;
      for (int i = k; i < n; i += st)
        p[i] = (p[i-k] + p[i+k])/2 + R*(Math.random()-.5);}
  }
  
  public void paint(Graphics g) {
    g.setColor(Color.white);   g.fillRect(0, 0, w, h+lbSize);
    int x = 0, x0 = 0, y, y0 = (int)(h2*p[0]) + h0;
    g.setColor(Color.red);
    x = x0 = 0;  y0 = (int)(h2*p[0]) + h0;
    for (int i = 0; i < n1; i++){
      x += 2;  y = (int)(h2*p[i]) + h0;
      g.drawLine(x0,y0 ,x,y);
      x0 = x;  y0 = y;}
  }
  
  public void actionPerformed(ActionEvent e){
    build();
    repaint();
  }
  public void keyTyped(KeyEvent e){}
  public void keyPressed(KeyEvent e){}
  public void keyReleased(KeyEvent e){
    final int keyEnter = 10;
    if (e.getKeyCode() == keyEnter){
      try{ m = Double.valueOf(tfM.getText()).doubleValue();
      }catch(NumberFormatException ne){}
      build();
      repaint();
    }
    e.consume();
  }
  public void update(Graphics g){ paint(g); }
  }