// Fractal contour plot,  Evgeny Demidov, 11 Feb 2002
  import java.awt.*;
  import java.awt.event.*;
  import java.awt.image.*;
  public class applet-math-contourF extends java.applet.Applet
   implements ItemListener, ActionListener{
    int  Rc = 2, w, h, lbSize = 30, iM[], maxColor = 60;
    double M[];
    Choice chRc;    Label lbRc;    Button btNew;
    Image img;      IndexColorModel iColor;
  
  public void init() {
    w = getSize().width;
    h = getSize().height - lbSize;
  
    int M=maxColor/3,  M2=2*M;
    long M4 = (long)M*M*M*M;
    byte rColor[] = new byte[maxColor+1], bColor[] = new byte[maxColor+1],
         gColor[] = new byte[maxColor+1];
    for (int i = 1; i < M2; i++){
      long dum = M - i;  dum *=dum;  dum *=dum;
      gColor[i] =  bColor[(i+M) % maxColor] = rColor[(i+M2) % maxColor] =
          (byte)(255 - (255*dum)/M4);}
    iColor = new IndexColorModel( 8, maxColor+1, rColor,gColor,bColor);
  
    lbRc = new Label("Rc", Label.RIGHT);  add(lbRc);
    chRc = new Choice();
    for (int i = 0, r = 1; i < 8; i++){
      chRc.addItem(Integer.toString(r));  r *= 2;}
    chRc.select("" + Rc);  chRc.addItemListener(this);  add(chRc);
    btNew = new Button("New");   btNew.addActionListener(this);
    add(btNew);
    averaging();
  }
  public void averaging(){
    double Vmin = 100, Vmax = -100, sV = 0, H = 2;
  
    int n=512, n1=n+1, nc=n, Max=n1*n1;
  
    M = new double[Max];
    while ( (nc /= 2) >= 1) {
      int ncn1 = nc*n1;    H /= 2;
      for (int j =ncn1; j < Max; j += ncn1+ncn1){
        for (int i = nc; i< n; i += nc+nc) {
          M[i+j] = (M[i+j+nc-ncn1] + M[i+j-nc+ncn1])/2.+H*(Math.random()-.5);
          M[i+j+nc] = (M[i+j+nc+ncn1] + M[i+j+nc-ncn1])/2.+H*(Math.random()-.5);
          M[i+j+ncn1] = (M[i+j-nc+ncn1] + M[i+j+nc+ncn1])/2.+H*(Math.random()-.5);
    }}}
    
    iM = new int[Max];
    for (int i = 0; i < Max; i++) iM[i] = (int)(40*(M[i]+1));
    img = createImage(new MemoryImageSource(n1, n1, iColor, iM, 0, n1));
  }
  
  public void paint(Graphics g) {
    g.drawImage(img, 0, lbSize, this);
  }
  
  public void itemStateChanged(ItemEvent e){
  //  Rc = Integer.parseInt(chRc.getSelectedItem());
    averaging();
    repaint();
  }
  public void actionPerformed(ActionEvent e){
  //  for (int i = 0; i < n; i++) p[i] = 2*Math.random() - 1;
    averaging();
    repaint();
  }
  public void update(Graphics g){ paint(g); }
  }