Add variuos amplitudes to sound graph

Question

Hi
I have the following code that computes a sound graph with a fixed amplitude for a number of waves. I need to be able to control the amplitude of each wave, but am not sure how to amend the following code to produce the effect. There is also an fft function that converts the amplitude time graph to frequency time graph, but I am not concerned for this now - only want to change the amplitude for n number of waves.
import java.awt.*;
import java.awt.event.*;
public class FFTv1 extends Frame
   implements ActionListener, WindowListener
  final int maxDim = 1024;
  int width =400, height =300;
  Button b;
  Complex x[];
  drawPanel pdraw;
  //float sam[] = {5, 10, 1};
  public FFTv1() {
// The title of the frame is "FFT".       
     super("FFT");
// Use the BorderLayoutlayout manager.    
     setLayout(new BorderLayout());
     addWindowListener(this);
// Instantiate a button with label "FFT" which when pressed takes the FT.
     b = new Button("FFT");
// Instantiate a panel object p where the button will be placed.    
     Panel p = new Panel();
// Place the panel p in the South position  of the frame.  
     add("South", p);
// Add the button to the panel p    
     p.add(b);
// The button listens for click events.    
     b.addActionListener(this);
// Instantiate an array x of type Complex with a length of maxDim.
// Loop over all the elements of the array setting them equal to the value of a test function
     x = new Complex[maxDim];
// Initialise the value of test function to zero for all sampling points x[i] = (0,0) for i = 0 to N-1.     
     for (int i=0; i < maxDim; i++) {
        x=new Complex(0.0f, 0.0f);
// The outer loop is over the N sample points.
// The inner loop is over the n number of graphs - in this case 2
// CAN AMPLITUDE BE ADDED BELOW??
     for (int i=0; i < maxDim; i++) {      
          for (int j=10; j < 30; j+=10) {               
     float arg = (float)(j*i * Math.PI/maxDim);
     x[i].setReal(x[i].getReal()+(float)Math.cos(arg));      
// Instantiate a panel object pdraw where the graph will be drawn.
pdraw = new drawPanel(x);
// Place the panel pdraw in the Center position of the frame.
add("Center", pdraw);
setBounds(100,100, width, height);
setVisible(true);
public void actionPerformed(ActionEvent e) {
// On clicking the button perform the FT on function contained in complex array x.
//Instantiate object fft of type FFT passing the array x to the constructor.
FFT fft = new FFT(x);
// The FT input data x is overwritten.
fft.Execute();
// The drawing panel pdraw needs to be repainted.
pdraw.repaint();
static public void main(String argv[]) {
// Instantiate an object of type FFTv1 which contains the GUI elements and thus drives the overall program.      
new FFTv1();
public void windowClosing(WindowEvent wEvt)
System.exit(0); //exit on System exit box clicked
public void windowClosed(WindowEvent wEvt){}
public void windowOpened(WindowEvent wEvt){}
public void windowIconified(WindowEvent wEvt){}
public void windowDeiconified(WindowEvent wEvt){}
public void windowActivated(WindowEvent wEvt){}
public void windowDeactivated(WindowEvent wEvt){}
To draw the graphs, we need drawPanel class
import java.awt.*;
class drawPanel extends Panel
   Complex x[];
   float ymin, ymax;
   float hscale, vscale;
   int ytop, ybot;
   float ampmax[] = {5, 10, 1};
   float ampmin[] = {-5, -10, -1};
   protected drawPanel(Complex xa[])
    x = xa;
    ymin = -1e9F;
    ymax = 1e9F;     
  public void paint(Graphics g)
      ymin = 1e9F;
      ymax = -1e9F;
       for (int i=0; i< x.length; i++)
          if (x.getReal() > ymax) {ymax = -2;}
     if (x[i].getReal() < ymin) {ymin = 2;}     
Dimension d = getSize();
hscale = (float)d.width/x.length;
vscale = 0.9f*((float)(d.height))/(ymax - ymin);
ytop = (int)(d.height*0.95);
ybot = 0;// (int)(d.height*0.05);
int x0 = calcx(0);
int y0 = calcy(x[0].getReal());
System.out.println(y0);
for (int i = 0; i < x.length; i++)
     int x1 = calcx(i);
     int y1 = calcy(x[i].getReal());
     g.drawLine(x0, y0, x1, y1);
     x0 = x1;
     y0 = y1;
private int calcx(int i)
return (int) (i*hscale);
private int calcy(float y)
     return ytop-(int)((y - ymin)*vscale)+ybot;     
//=============================================
I am hoping someone can help, as I have spent hours trying to change the amplitude - I thought it may be ymax and ymin of drawPanel - but then I cannt get n number of waves at the required frequency.
Please help!
Thanks
sam

Answer 1

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By the way, that Abort VI button is not for stopping your loops.  I just kills execution wherever it may be.  It should only be used as a last resort if your stopping code is not working properly.
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