import awb.*;
import java.awt.*;
import java.awt.event.*;

public class Recurse extends java.applet.Applet implements ActionListener
{
    TextField gMake, gStyle, gColor, gOwner, mInstruct;
    IntField gN;
    DoubleField gX;                                      
    Label lN, lX;  
    Button bFact, bExp;                         
    TextField mResults;
    int k, n;
    double x;
   
    public void init()
    {   
        lN = new Label("N");
        lX = new Label("X");
        mInstruct = new TextField(60);
        mInstruct.setText("Enter N and X, then press button for function");
        gN = new IntField(10);
        gX = new DoubleField(10);
        bFact = new Button("Factorial");
        bExp = new Button("Exponential");
        mResults = new TextField(60);
        bFact.addActionListener(this);
        bExp.addActionListener(this);
        
        add(mInstruct);
        add(lN);
        add(gN);
        add(lX);
        add(gX);
        add(bFact);
        add(bExp);
        add(mResults);
    }           
        
    public void actionPerformed(ActionEvent event)
    {
        Object cause = event.getSource();
        
        if (cause == bFact)                                                    
        {
            n = gN.getInt();
            x = gX.getDouble();
            mResults.setText(n+" factorial = "+fact(n));
        }
        if (cause == bExp)
        {
            n = gN.getInt();
            x = gX.getDouble();
            mResults.setText(x+" to the "+n+" power = "+expon(x, n));
        }
    }
    

    int fact(int n)
    {
        if (n<=1)
        {
            return 1;
        }
        
        return n * fact(n-1);
    }
    
    double expon(double x, int n)
    {
        double xnot;
        
        if (n == 0)
        {
            return 1.0;
        }
        xnot = expon(x, n/2);
        if ( n == 2*(n/2))
        {
            return xnot * xnot;
        }
        else
        {
            return x * xnot * xnot;
        }
    }
}