The Derivative as a Limit Applet -- Source


import java.awt.*;
import java.applet.*;
import java.lang.*;

public class Experiment extends Applet
{    private TextField InputText  = new TextField(30);
     private Button    GoButton   = 
             new Button("Then click here to run the experiment.");
     private TextField OutputText = new TextField(30);

     public boolean action(Event evt, Object arg)
     {     String UserInput;
           double UserNumber;
           double OutputNumber;   

           if (evt.target instanceof Button)
           {  UserInput = InputText.getText().trim();
              UserNumber = Double.valueOf(UserInput).doubleValue();
              OutputNumber = java.lang.Math.cos(1.24 * UserNumber) + 2.5423;
              OutputText.setText("Output: " + 
                   java.lang.Double.toString(OutputNumber));
              return true;
           }
           else
              return false;
     }
       

     public void init()
     {
           setBackground(Color.white);
           setFont(new Font("Courier", Font.BOLD, 14));
           add(new Label(" Enter your input in the box below."));     
           add(InputText);
           add(GoButton);
           add(OutputText);
     }

}