/*
 * qm4.java - revised 27 Dec 07 - width 401, height 301
 * @author jackord@kw.igs.net
 * superposition of the two lowest energy states of a double well (an
 *   infinite square well with a central barrier)
 */

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

public class qm4 extends Applet
                 implements ActionListener {
  int kk=0; int plt=0; int first=0;                    // Declarations
  String b1s="P Dens"; Button b1=new Button(b1s);
  String b2s="Yr Yi"; Button b2=new Button(b2s);
  String b3s="Motion"; Button b3=new Button(b3s);
  Image bim;
  Graphics bgr;
                                           
  public void init() {
    setLayout(new FlowLayout(FlowLayout.LEFT));
    setBackground(new Color(211, 211, 211));
    add(b1); b1.addActionListener(this);
    add(b2); b2.addActionListener(this);
    add(b3); b3.addActionListener(this);
  }

  public void paint(Graphics g) {                     
    int nf, jt, del, tdel;
    double a, c, e, ea, eb, v, pi, dt, yr, yi, sa, sb;
    int n=400;
    double [] ya=new double[n+1];
    double [] yb=new double[n+1];
    int [] xx=new int[n+1];
    int [] yy=new int[n+1];
    int [] zz=new int[n+1];
    if (first==0) {
      bim=createImage(401, 301);                       // Animation buffer
      bgr=bim.getGraphics();
      first=1;
    }
    g.setColor(Color.green); g.fillRect(192, 0, 16, 300);  // Initial screen
    g.setColor(Color.black); g.drawRect(0, 0, 400, 300);
    g.drawLine(0, 150, 400, 150);
    g.setColor(Color.blue);
    if (kk==1) { nf=320; del=25; } else { nf=4000; del=10; }
    pi=Math.PI; c=Math.PI/400; c=c*c;
    ea=3.8529754; eb=4.07504;                          // Energy eigenvalues
    if (kk>0) {                              
      e=ea; ya[0]=0; v=0.9; sa=0;
      for (int i=1; i<=n-1; i=i+1) {                   // State 1, ya[i]
        ya[i]=ya[i-1]+v; sa=sa+ya[i]*ya[i];
        if ((i>191)&&(i<209)) { a=(200-e)*c; } else { a=-e*c; }
        v=v+a*ya[i];
      }
      e=eb; yb[0]=0; v=0.9; sb=0;
      for (int i=1; i<=n-1; i=i+1) {                   // State 2, yb[i]
        yb[i]=yb[i-1]+v; sb=sb+yb[i]*yb[i];
        if ((i>191)&&(i<209)) { a=(200-e)*c; } else { a=-e*c; }
        v=v+a*yb[i];
      }
      sb=Math.sqrt(sa/sb);                             // Normalize
      for (int i=0; i<=n; i=i+1) { xx[i]=i; yb[i]=sb*yb[i]; }
      a=2*pi/(eb-ea)/nf;
      jt=0; long tt=System.currentTimeMillis(); 
      do {                                             // Frame loop
        bgr.setColor(getBackground());                 // Set up plot buffer
        bgr.fillRect(0, 0, 400, 300);
        bgr.setColor(Color.green); bgr.fillRect(192, 0, 16, 300);
        bgr.setColor(Color.black); bgr.drawRect(0, 0, 400, 300);
        bgr.drawString("Frm "+jt+"/"+nf, 300, 20);
        bgr.setColor(Color.blue);
        for (int i=0; i<=n; i=i+1) {                   // Superposition
          yr=ya[i]*Math.cos(jt*ea*a)+yb[i]*Math.cos(jt*eb*a);
          yi=ya[i]*Math.sin(jt*ea*a)+yb[i]*Math.sin(jt*eb*a);
          if (kk==2) {
            yy[i]=150-(int)(yr+.5);                    // Yr
            zz[i]=150-(int)(yi+.5);                    // Yi
          }
          else {
            yy[i]=300-(int)(.019*(yr*yr+yi*yi)+.5);
          }
        }
        if (kk==2) {
          bgr.drawPolyline(xx, yy, n+1); bgr.setColor(Color.red);   // Yr
          bgr.drawPolyline(xx, zz, n+1); bgr.setColor(Color.blue);  // Yi
        }
        else {
          bgr.fillPolygon(xx, yy, n+1);
        }
        g.drawImage(bim, 0, 0, null);                  // Show plot buffer
        while (tt>System.currentTimeMillis()) { }
        tt=tt+del; jt=jt+1; if (jt==nf+1) { plt=0; kk=0; }
      } while (plt==1);
    }
  }

  public void actionPerformed(ActionEvent e) {         // Buttons
    String tst;
    tst=e.getActionCommand();
    if (b1s.equals(tst)) { kk=1; }
    if (b2s.equals(tst)) { kk=2; }
    if (b3s.equals(tst)) { if (kk>0) { plt=1; } }
    repaint();
  }
}