/*
 * h5a.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 h5a extends Applet 
                     implements ActionListener {
  int k=0;                                             // Declarations
  double s, s1, b, c, yo, vo;
  String b1s = "BB1"; Button bb1 = new Button(b1s);
  String b2s = "BB2"; Button bb2 = new Button(b2s);
  String b3s = "BB3"; Button bb3 = new Button(b3s);
  String h1s = "HO1"; Button ho1 = new Button(h1s);
  String h2s = "HO2"; Button ho2 = new Button(h2s);
  String h3s = "HO3"; Button ho3 = new Button(h3s);

  public void init() {                                 // Layout
    add(bb1); add(bb2); add(bb3);
    add(ho1); add(ho2); add(ho3);
    bb1.addActionListener(this);
    bb2.addActionListener(this);
    bb3.addActionListener(this);
    ho1.addActionListener(this);
    ho2.addActionListener(this);
    ho3.addActionListener(this);
    setBackground(new Color(211, 211, 211));
  }

  double fey(double e, Graphics g) {                   // Feynman Algorithm
    double x, y, v, a, dx;
    int x1, y1, x2, y2;
    int i=0; int n=500; dx=.002;
    x=0; y=yo; v=vo; s=y*y*dx/2; x1=0; y1=(int)(150*(1-y));
    if (k==1) { a=e*e*e*(x-1)*y; } else { a=e*e*(x*x-1)*y; }
    v=v+a*dx/2;
    while ((y>-1) && (y<1) && (x<3)) {
      i=i+1; x=x+dx; y=y+v*dx; x2=(int)(200*x); y2=(int)(150*(1-y));
      g.drawLine(x1, y1, x2, y2); x1=x2; y1=y2;
      if (k==1) { a=e*e*e*(x-1)*y; } else { a=e*e*(x*x-1)*y; }
      v=v+a*dx;
      if ((x<1) || (v*y<0)) {                          // Trapezoid Algorithm
        s=s+y*y*dx; if (i==n) { s1=s-y*y*dx/2; }
      }
    }
    return y;
  }

  public void paint(Graphics g) {                      // Bisection Algorithm
    double e, de, yb, yc;
    g.setColor(Color.black);
    g.drawRect(0, 0, 600, 300);
    g.setFont(new Font("TimesRoman", Font.PLAIN, 14));
    g.drawLine(0, 150, 600, 150);
    g.drawLine(200, 0, 200, 300); g.drawLine(400, 0, 400, 300);
    g.setColor(Color.blue);
    if (k>0) {
      de=0.00001;
      yb=fey(b, g); yc=fey(c, g);
      if (yb*yc<0) {
        while ((c-b)>de) {
          e=(b+c)/2; if (fey(e, g)*yb>0) { b=e; } else { c=e; }
        }
        g.setColor(Color.red); e=(b+c)/2; yb=fey(e, g);
        g.drawString("Energy EigenValue ="+(float)e, 220, 260);
        g.drawString("Probability z>1 ="+(float)(1-s1/s), 220, 280);
      }
    }
    k=0;
  }

  public void actionPerformed(ActionEvent e) {         // Buttons
    String tst;
    tst=e.getActionCommand();
    if (b1s.equals(tst)) { k=1; b=2; c=3; yo=0; vo=2; }
    if (b2s.equals(tst)) { k=1; b=3; c=5; yo=0; vo=4; }
    if (b3s.equals(tst)) { k=1; b=5; c=6; yo=0; vo=8; }
    if (h1s.equals(tst)) { k=2; b=.5; c=1.5; yo=.8; vo=0; }
    if (h2s.equals(tst)) { k=2; b=2; c=4; yo=0; vo=2; }
    if (h3s.equals(tst)) { k=2; b=4; c=6; yo=.8; vo=0; }
    repaint();
  }
}