// MatrixWindow.java

// Written by Julian Devlin, 8/97, for the text book
// "Introduction to Probability," by Charles M. Grinstead & J. Laurie Snell

import java.applet.Applet;
import java.awt.*;

public class MatrixWindow
	extends java.awt.Frame
{
	Panel dispArea;
	Panel controls;		// Panel for user controls
	Panel matPanel;
	
	Label numl;			// Controls
	TextField num;
	
	TextField[][] m;
	Matrix myMat;
	
	Button go;
	
	GridBagLayout gbl, mgbl;
	GridBagConstraints cc, mcc;
	
	int size;
	
	public MatrixWindow(int n) {
		super("MatrixPowers");
		size = n;
	}
	
	// Initialize applet
	public void init()
	{	
		numl = new Label("Power = ");			// Create controls
		num = new TextField("1", 4);
		go = new Button("Go");
		
		if (size == 3) {
			m = new TextField[size][size];
			m[0][0] = new TextField(".5", 4);
			m[0][1] = new TextField(".25", 4);
			m[0][2] = new TextField(".25", 4);
			m[1][0] = new TextField(".5", 4);
			m[1][1] = new TextField("0", 4);
			m[1][2] = new TextField(".5", 4);
			m[2][0] = new TextField(".25", 4);
			m[2][1] = new TextField(".25", 4);
			m[2][2] = new TextField(".5", 4);
		}
		else {
			m = new TextField[size][size];
			for (int r = 0; r < size; r++) {
				for (int c = 0; c < size; c++) {
					m[r][c] = new TextField("0", 4);
				}	
			}
		}
			
		dispArea = new Panel();				// Set up window
		controls = new Panel();
		matPanel = new Panel();
		setLayout(new BorderLayout(5, 5));
		
		add("South", controls);
		add("Center", dispArea);
		
		mgbl = new GridBagLayout();
		mcc = new GridBagConstraints();
		matPanel.setLayout(mgbl);
		for (int r = 0; r < size; r++) {
			for (int c = 0; c < size; c++) {
				mcc.gridx = c;
				mcc.gridy = r;
				mgbl.setConstraints(m[r][c], mcc);
				matPanel.add(m[r][c]);
			}	
		}
		
		dispArea.setLayout(new GridLayout(1, 2));
		dispArea.add(matPanel);
		
		myMat = new Matrix(m);
		
		dispArea.add(myMat);
		
		gbl = new GridBagLayout();
		controls.setLayout(gbl);
		
		cc = new GridBagConstraints();
		
		cc.gridx = 0;
		cc.gridy = 0;
		gbl.setConstraints(numl, cc);
		controls.add(numl);
		
		cc.gridx = 1;
		gbl.setConstraints(num, cc);
		controls.add(num);
		
		cc.gridx = 0;
		cc.gridy = 1;
		cc.gridwidth = 2;
		gbl.setConstraints(go, cc);
		controls.add(go);
		
		validate();
	}
	
	// Handle events
	public boolean handleEvent(Event evt)
	{
		String minStr, maxStr;
		if (evt.target instanceof Button)
		{
			if (evt.target == go && evt.id == Event.ACTION_EVENT)	// When button is clicked
			{
        		simulate(Integer.valueOf(num.getText()).intValue());
        		return true;					// Generate correct number of tosses
			}
		}
		if (evt.id == Event.WINDOW_DESTROY) {
			hide();
			dispose();	
		}
		return super.handleEvent(evt);	// Handle other events as usual
	}
	
	// Calculate probabilities
    public void simulate(int num)
    {	
    	dispArea.remove(myMat);
    	myMat = new Matrix(m);
   	 	Matrix temp = myMat;
   	 	for (int i = 1; i < num; i++) {	// Do nothing for 1st power
   	 		myMat = Matrix.multiply(temp, myMat);	
   	 	}
   	 	myMat.round(.001f);
   	 	dispArea.add(myMat);
   	 	validate();
	}
	
	public float round(float num, float accuracy) {
		return accuracy * Math.round(num / accuracy);
	}
	
}