/*
 * h5b.java - revised 19 Apr 05 - width 601, height 301
 * @author jackord@kw.igs.net
 */

import java.applet.Applet;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class h5b extends Applet
                   implements ActionListener {
  int kk=0;                                            // Declarations
  String bs="Plot"; Button b=new Button(bs);

  public void init() {
    setLayout(new FlowLayout(FlowLayout.LEFT));
    add(b);
    b.addActionListener(this);
    setBackground(new Color(211, 211, 211));
  }

  public void fey(double e, double v, Graphics g) {    // Feynman Algorithm
    double x, y, a, dx;
    int x1, y1, x2, y2;
    dx=.002;
    x=0; y=0; x1=0; y1=300;
    a=e*e*e*(x-1)*y; v=v+a*dx/2;
    while (((x<1) || (v*y<0)) && (x<8)) {
      x=x+dx; y=y+v*dx;
      x2=(int)(75*e*x); y2=(int)(60*(5-y*y));
      g.drawLine(x1, y1, x2, y2); x1=x2; y1=y2;
      a=e*e*e*(x-1)*y; v=v+a*dx;
    }
    x=0; y=4/e; x1=0; y1=(int)(60*(5-y));              // Plot Classical 
    while (y<5) {
      x=x+dx; y=4/e/Math.sqrt(1-x);
      x2=(int)(75*e*x); y2=(int)(60*(5-y));
      g.drawLine(x1, y1, x2, y2); x1=x2; y1=y2;
    }
    x1=(int)(75*e); g.drawLine(x1, 0, x1, 300);
  }

  public void paint(Graphics g) {                      // Paint
    double e, vo;
    g.setColor(Color.black);
    g.drawRect(0, 0, 600, 300);
    g.setFont(new Font("TimesRoman", Font.PLAIN, 14));
    if (kk==1) {
      g.setColor(Color.blue); e=2.33811; vo=6.61317; fey(e, vo, g);
      g.setColor(Color.magenta); e=4.08793; vo=11.5622; fey(e, vo, g);
      g.setColor(Color.red); e=5.5205; vo=15.61338; fey(e, vo, g);
    }
    kk=0;
  }

  public void actionPerformed(ActionEvent e) {
    String tst;
    tst=e.getActionCommand();
    if (bs.equals(tst)) { kk=1; }
    repaint();
  }
}