/*
 * nm3.java - revised 28 Mar 07 - width 397, height 241
 * @author jackord@kw.igs.net
 * string of length 8d, clamped at both ends
 * equal point masses at intervals of d
 * finite and infinite Fourier Sine Series representations of
 * 'pluck' and 'pulse' initial displacements
 */

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

public class nm3 extends Applet
                 implements ActionListener {
  int kk=0; int ff=0;                                  // Declarations
  String b1s="Pluck FFSS"; Button b1=new Button(b1s);
  String b2s="Pulse FFSS"; Button b2=new Button(b2s);
  String b3s="Pluck FSS"; Button b3=new Button(b3s);
  String b4s="Pulse FSS"; Button b4=new Button(b4s);

  public void init() {
    add(b1); add(b2); add(b3); add(b4);
    b1.addActionListener(this);
    b2.addActionListener(this);
    b3.addActionListener(this);
    b4.addActionListener(this);
    setBackground(new Color(211, 211, 211));

  }

  public void paint(Graphics g) {
    int n, r, y1, y2;                                  // Declarations
    double z;                                          
    double [] a=new double[9];
    double [] b=new double[9];
    double [] y=new double[9];
    g.setColor(Color.black);
    g.drawRect(0, 0, 396, 240);
    n=8; r=3;
    if (kk!=0) {
      if (kk==1) {                                     // Initialize pluck
        for (int i=0; i<=n/2; i=i+1) {
          y[i]=40*i; y[n-i]=y[i];
        }
        for (int i=1; i<n; i=i+2) {                    // Pluck FSS coeffts
          a[i]=80*Math.pow(4/Math.PI/i, 2)*Math.sin(i*Math.PI/2);
        }
      }
      if (kk==2) {                                     // Initialize pulse
        y[4]=160;
        for (int i=1; i<n; i=i+2) {                    // Pulse FSS coeffts
          a[i]=Math.sin(Math.PI*i/2)-Math.sin(Math.PI*i*3/8);
          a[i]=a[i]*80*Math.pow(8/Math.PI/i, 2);
        }
      }
      if (ff==1) {                                     // FFSS coeffts
        for (int i=1; i<n; i=i+2) {
          for (int j=1; j<n; j=j+1) {
            b[i]=b[i]+2*y[j]/n*Math.sin(Math.PI*i*j/n);
          }
        }
      }
      if (ff==2) {                                     // Select FSS
        for (int i=1; i<n; i=i+2) {                    
          b[i]=a[i];
        }
      }
      g.setColor(Color.blue);
      for (int i=1; i<=n; i=i+1) {                     // Draw displacement
        g.drawLine(6+48*(i-1), 195-(int)(y[i-1]+.5), 6+48*i, 195-(int)(y[i]+.5));
      }
      for (int i=0; i<=n; i=i+1) {
        g.fillArc(6+48*i-r, 195-(int)(y[i]+.5)-r, 2*r+1, 2*r+1, 0, 360);
      }
      g.setColor(Color.green);
      for (int i=1; i<n; i=i+2) {                      // Draw components
        y1=195;
        for (int j=1; j<=48*n; j=j+1) {
          y2=195-(int)(b[i]*Math.sin(Math.PI*i*j/n/48)+.5);
          g.drawLine(6+j-1, y1, 6+j, y2);
          y1=y2;
        }
      }
      g.setColor(Color.red);
      y1=195;
      for (int j=1; j<=48*n; j=j+1) {                  // Sum components
        z=0;
        for (int i=1; i<n; i=i+2) {
          z=z+b[i]*Math.sin(Math.PI*i*j/n/48);
        }
        y2=195-(int)(z+.5);
        g.drawLine(6+j-1, y1, 6+j, y2);
        y1=y2;
      }
    }
    kk=0;
  } 

  public void actionPerformed(ActionEvent e) {
    String tst;
    tst=e.getActionCommand();
    if (b1s.equals(tst)) { kk=1; ff=1; }
    if (b2s.equals(tst)) { kk=2; ff=1; }
    if (b3s.equals(tst)) { kk=1; ff=2; }
    if (b4s.equals(tst)) { kk=2; ff=2; }
    repaint();
  }
}