import java.awt.*;
import java.awt.event.*;

public class c01_iteration extends java.applet.Applet {
  double a = 2.75;
  double x0 = 0.2;
  static final int left = 30;
  static final int w = 300;
  static final int m = 1;
  static final int imax = 10;
  Graph graph;
  Controls controls;

  class Graph extends Canvas {
    public void paint(Graphics g)
    {
      LineTo lt = new LineTo(g);
      lt.drawLine(left+w, left, left, left+w);
      for (int i = 1; i <= w; i++) {
        double xn = (double)i/w;
        for (int k = 1; k <= m; k++) {
          xn = a * xn * (1-xn);
        }
        lt.lineTo(i+left, (int)(left+w*(1-xn)));
      }
      double xn = x0;
      double x = x0;
      lt.moveTo((int)(left+w*xn), left+w);
      for (int i = 1; i <= imax; i++) {
        for (int k = 1; k <= m; k++) {
          xn = a * xn * (1-xn);
        }
        lt.lineTo((int)(left+w*x), (int)(left+w*(1-xn)));
        lt.lineTo((int)(left+w*xn), (int)(left+w*(1-xn)));
        x = xn;
      }
    }
  }

  class Controls extends Container {
    private TextField ta;
    private TextField tx0;
    private Button redraw;

    public Controls()
    {
      setLayout(new FlowLayout());
      add(new Label("a =", Label.RIGHT));
      add(ta = new TextField(""+a, 6));
      add(new Label("x0 =", Label.RIGHT));
      add(tx0 = new TextField(""+x0, 6));
      add(redraw = new Button("Redraw"));
      redraw.addActionListener(
        new ActionListener() {
          public void actionPerformed(ActionEvent e) {
            try {
              a = Double.valueOf(ta.getText()).doubleValue();
              x0 = Double.valueOf(tx0.getText()).doubleValue();
            } catch (NumberFormatException nfx) {
            }
            c01_iteration.this.graph.repaint();
          }
        }
      );
    }
  }

  public void init()
  {
    setLayout(new BorderLayout());
    add(controls = new Controls(), BorderLayout.SOUTH);
    add(graph = new Graph(), BorderLayout.CENTER);
    graph.addMouseListener(
      new MouseAdapter() {
        public void mouseClicked(MouseEvent e)
        {
          x0 = (double)(e.getX() - left) / w;
          x0 = (double)Math.round(x0*100) / 100;
          controls.tx0.setText(""+x0);
          graph.repaint();
        }
      }
    );
  }
}