// Interactive X = R X(1-X) Iterations,  Evgeny Demidov, 18 Nov 2005
import java.awt.*;
import java.awt.event.*;

public class @file 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);  }

}