// Interactive X = R X(1-X) Iterations,  Evgeny Demidov, 18 Nov 2005
  import java.awt.*;
  import java.awt.event.*;
  
  public class applet-math-fractal-logistic-it extends java.applet.Applet
         implements MouseMotionListener, KeyListener {
  Image buffImage;          Graphics buffGraphics;
  int maxIt = 10, N = 1, numIt,  w,h,h2,  lbSize = 30,
      xFun[],yFun[],  xGist[],yGist[], xIt[],yIt[];
  double R = 2, maxIYI = 2.,  Step;
  Label     lbIt, lbN, lbR;
  TextField tfIt, tfN, tfR;
  
  public void init() {
    h = Integer.parseInt(getParameter("height")) - lbSize;  h2 = h/2;
    w = Integer.parseInt(getParameter("width"));
    String s=getParameter("MaxIt"); if (s != null) maxIt=Integer.parseInt(s);
    s=getParameter("N"); if (s != null) N=Integer.parseInt(s);
    s = getParameter("R");  if (s != null) R = Double.valueOf(s).doubleValue();
    xFun = new int[h];    for (int i = h-1; i >= 0; i--) xFun[i] = i;
    yFun = new int[h];
    buffImage = createImage(w, h);
    buffGraphics = buffImage.getGraphics();
    lbR = new Label("R");             add(lbR);
    tfR = new TextField( "" + R, 9);  add(tfR);
    lbN = new Label("N");             add(lbN);
    tfN = new TextField( "" + N, 3);  add(tfN);
    lbIt = new Label("It");                add(lbIt);
    tfIt = new TextField( "" + maxIt, 3);  add(tfIt);
    tfR.addKeyListener(this);   tfN.addKeyListener(this);
    tfIt.addKeyListener(this);
    addMouseMotionListener(this);
  
    Step = 1. / h;
    draw();
  }
  
  public void destroy() {  removeMouseMotionListener(this); }
  public void keyTyped(KeyEvent e) {}
  public void keyPressed(KeyEvent e) {}
  public void keyReleased(KeyEvent e) {
    final int keyEnter = 10;
    if (e.getKeyCode() == keyEnter) {
      try{
        N = Integer.parseInt( tfN.getText() );
        maxIt = Integer.parseInt( tfIt.getText() );
        R = Double.valueOf(tfR.getText()).doubleValue();
      }catch ( NumberFormatException ne) {}
      draw();    repaint();
    }
    e.consume();
  }
  
  public void mouseMoved(MouseEvent e) {}
  public void mouseDragged(MouseEvent e) {
    R = 4*Step*(h - (e.getY() - lbSize));
    tfR.setText( Float.toString((float)R) );
    draw();    repaint();
    e.consume();
  }
  
  public void draw() {
    xGist = new int[maxIt<<1 + 1];    yGist = new int[maxIt<<1 + 1];
    xIt = new int[maxIt+1];    yIt = new int[maxIt+1];
    for (int i = 0; i <= maxIt; i++)
      xIt[i] = h + (int)((w-h-1)*(double)i/(maxIt));
    generateFun();        iterations();
    buffGraphics.setColor(Color.white);
    buffGraphics.fillRect(0, 0, w  - 1, h - 1);
    buffGraphics.setColor(Color.black);
    buffGraphics.drawRect(0, 0, w  - 1, h - 1);
    buffGraphics.drawLine(h, 0, h, h - 1);
    buffGraphics.setColor(Color.green);
    buffGraphics.drawLine(0, h, h, 0);
    buffGraphics.setColor(Color.blue);
    buffGraphics.drawPolyline( xFun, yFun, h );
    buffGraphics.setColor(Color.red);
    buffGraphics.drawPolyline( xGist, yGist, numIt<<1 );
    buffGraphics.drawPolyline( xIt, yIt, numIt+1 );
  }
  
  public void paint(Graphics g) {
    g.drawImage(buffImage, 0, lbSize, this);
    showStatus( "It=" + numIt);
  }
  
  public void iterations() {
    double X = .5,  Y;         int bakX, bakY,iY;
    xGist[0] =  bakX = h2;
    yGist[0] = h;  yIt[0] = h2;
    for (int i = 1; i <= maxIt; i++) {
      Y = X;
      for (int n = N; n > 0; n--)   Y = R*Y*(1-Y);
      iY = (int)(Y/Step);
      int i2 = i<<1;
      xGist[i2 - 1] = bakX;
      yGist[i2 - 1] =  bakY = h - iY;
      xGist[i2] = bakX = iY;
      yGist[i2] = yIt[i] = bakY;
      X = Y;    numIt = i;
      if (Math.abs(Y) > maxIYI) break;
    }
  }
  
  public void generateFun() {
    for (int i = h - 1; i >= 0; i--) {
      double X = i*Step;
      for (int n = N; n > 0; n--)   X = R*X*(1.-X);
      yFun[i] = h - (int)(X/Step);
    }
  }
  
  public void update(Graphics g)   {  paint(g);  }
  
  }