//<APPLET CODE="LeastSquares.class" width="382" height="433"></applet>

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

public class LeastSquares extends Applet {
	Choice c;
	GraphPanel gp;
	Checkbox cb1,cb2;

	public void init(){
		setBackground(Color.white);

		c = new Choice();
		CheckboxGroup cbg = new CheckboxGroup();
		cb1 = new Checkbox("Fit Y to X",cbg,true);
		cb2 = new Checkbox("Fit X to Y",cbg,false);

		gp = new GraphPanel(c,cb1);
		add(gp);
		
		add(step1());
		add(step234(step2n3()));
		//add(step2(c));
		//add(step3());
		//add(step4());
	}

	public Panel step2n3(){
		Panel p = new Panel();
		p.setLayout(new GridLayout(1,2,2,2));
		p.setBackground(Color.white);
		p.add(step2(c));
		p.add(step3(cb1,cb2));
		return p;
	}

	public Panel step234(Panel p1){
		Panel p = new Panel();
		p.setLayout(new GridLayout(2,1,2,2));
		p.setBackground(Color.white);
		p.add(p1);
		p.add(step4());
		return p;
	}

	public Panel step1(){
		Panel p = new Panel();
		p.setBackground(Color.white);
		p.add(new Label("Select points by clicking on the graph or press "));
		p.add(new Button("Example"));	
		return p;
	}

	public Panel step2(Choice c){
		Panel p = new Panel();
		p.setBackground(Color.white);
		p.add(new Label("Degree of polynomial:"));
		p.add(c);	
		return p;
	}

	public Panel step3(Checkbox cb1, Checkbox cb2){
		Panel p = new Panel();
		p.setBackground(Color.white);

		p.setLayout(new GridLayout(2,1));
		p.add(cb1);
		p.add(cb2);

		return p;
	}

	public Panel step4(){
		Panel p = new Panel();
		p.setBackground(Color.white);
		p.add(new Button("Calculate"));
		p.add(new Button("View Polynomial"));	
		p.add(new Button("Reset"));	
		return p;
	}

	public boolean action(Event evt, Object arg){
		if (arg.equals("View Polynomial"))
			gp.showFrame();
	
		if (arg.equals("Reset"))
			gp.reset();
	
		if (arg.equals("Example"))
			gp.addExample();

		if (arg.equals("Calculate"))
			gp.fitDraw = true;

		//if (evt.target instanceof Choice){
		//if (evt.target == cb1){

		gp.repaint();
		return true;
	}

} // _LeastSquares()

//
//----------------------------------------------------------
//
class GraphPanel extends Panel {
	Dimension size = new Dimension(300,300);
	final Color myColor = new Color(255,255,200);
	int current, max;
	Point point[];
	Choice c;
	Checkbox cb;
	boolean fitDraw;
	GraphFrame gf;

  	public Dimension getMinimumSize()  {return size;}
	public Dimension getPreferredSize(){return size;}

	public GraphPanel(Choice c, Checkbox cb){
		setBackground(myColor);
		max = 75;
		this.c = c;
		this.cb = cb;
		gf = new GraphFrame();
		reset();
	}

	public void showFrame(){
		gf.show();
	}

	public void paint(Graphics g){
		drawTicks(g);
		drawPoints(g);			
		
		if (fitDraw)
			drawFit(g);

		// Draw Panel border
		g.setColor(Color.black);
		g.drawRect(0,0,size.width-1,size.height-1);
	}

	public void drawFit(Graphics g){
		int numPoints = current;
		int degreePoly =  0;

		try {
		degreePoly = 1+(int)Integer.parseInt(c.getSelectedItem());
		} catch(NumberFormatException e){
			c.select(1);
			degreePoly = 2;
		}
		Jama.Matrix mat = new Jama.Matrix(numPoints,degreePoly);
		double ab[];
		Jama.Matrix bmat;
		
		if (cb.getState()){
			for (int j=0;j<degreePoly;j++)
				for (int i=0;i<current;i++)
					mat.set(i,j,Math.pow(point[i].x/30.0,j));

			// Set B Matrix
			bmat = new Jama.Matrix(current,1);
			for (int i=0;i<current;i++)
				bmat.set(i,0,(300-point[i].y)/30.0);

			try {
				ab = mat.solve(bmat).getRowPackedCopy();
				//for (int i=0;i<ab.length;i++)
				//	System.out.println("F: "+ab[i]);
				g.setColor(Color.red);
				gf.init(ab);
				plotFit(ab,g);
			} catch(RuntimeException e){
				System.out.println("Singular");
				g.setColor(Color.red);
				g.drawString("Matrix is singular",100,100);
				double at[] = {0.0,0.0,0.0};
				gf.init(at);
			}
		} else {
			for (int j=0;j<degreePoly;j++)
				for (int i=0;i<current;i++)
					mat.set(i,j,Math.pow((300-point[i].y)/30.0,j));

			// Set B Matrix
			bmat = new Jama.Matrix(current,1);
			for (int i=0;i<current;i++)
				bmat.set(i,0,(point[i].x)/30.0);
			
			try {
				ab = mat.solve(bmat).getRowPackedCopy();

				g.setColor(Color.red);
				plotFit2(ab,g);
				gf.init(ab);
			} catch(RuntimeException e){
				System.out.println("Singular");
				g.setColor(Color.red);
				g.drawString("Matrix is singular",100,100);
			}
		}
	}

	public void plotFit2(double a[], Graphics g){
		int intervalNum = size.width;
		double intervalSize = 10/(intervalNum*1.0);
		for (int i=0;i<intervalNum;i++)
			drawThingy(getY(i*intervalSize,a),(i*intervalSize),getY((i+1)*intervalSize,a),((i+1)*intervalSize),g);

	}

	public void plotFit(double a[], Graphics g){
		int intervalNum = size.width;
		double intervalSize = 10/(intervalNum*1.0);
		for (int i=0;i<intervalNum;i++)
			drawThingy(i*intervalSize,getY(i*intervalSize,a),(i+1)*intervalSize,getY((i+1)*intervalSize,a),g);

	}
	public void drawThingy(double x1, double y1, double x2, double y2,Graphics g){
		int ix1 = (int)Math.round(30*x1);
		int iy1 = 300-(int)Math.round(30*y1);
		int ix2 = (int)Math.round(30*x2);
		int iy2 = 300-(int)Math.round(30*y2);

		g.drawLine(ix1,iy1,ix2,iy2);
	}

	public double getY(double x, double a[]){
		double y = 0;
		for (int i=0;i<a.length;i++)
			y+= a[i]*Math.pow(x,i);

		return y;
	}

	public void drawPoints(Graphics g){
		g.setColor(Color.blue);
		for (int i=0;i<current;i++)
			g.fillOval(point[i].x,point[i].y,3,3);
	}

	public void drawTicks(Graphics g){
		g.setColor(new Color(220,220,200));
		for (int i=0;i*30<size.width;i++)
			g.drawLine(i*30,size.height,i*30,0);

		for (int i=0;i*30<size.height;i++)
			g.drawLine(0,i*30,size.width,i*30);

	}

	public boolean mouseDown(Event evt, int x, int y){
		addPoint(x,y);
		repaint();
		return true;
	}

	public void addExample(){
		addPointTen(0.0,2.9);
		addPointTen(0.5,2.7);
		addPointTen(1.0,4.8);
		addPointTen(1.5,5.3);
		addPointTen(2.0,7.1);
		addPointTen(2.5,7.6);
		addPointTen(3.0,7.7);
		addPointTen(3.5,7.6);
		addPointTen(4.0,9.4);
		addPointTen(4.5,9.0);
		addPointTen(5.0,9.6);
		addPointTen(5.5,10.0);
		addPointTen(6.0,10.2);
		addPointTen(6.5,9.7);
		addPointTen(7.0,8.3);
		addPointTen(7.5,8.4);
		addPointTen(8.0,9.0);
		addPointTen(8.5,8.3);
		addPointTen(9.0,6.6);
		addPointTen(9.5,6.7);
		addPointTen(10.0,4.1);
		repaint();
	}

	public void addPointTen(double x, double y){
		fitDraw = false;
		addPoint((int)Math.round(x*30),size.height-(int)Math.round(y*30));
	}

	public void addPoint(int x, int y){
		if (current < max-1) {
			point[current].x = x;
			point[current].y = y;
			if (current > 0)
				c.addItem(""+(current));
			current++;
		}
	}

	public void reset(){
		point = new Point[max];
		for (int i=0;i<max;i++)
			point[i] = new Point(-5,-5);
		current = 0;
		fitDraw = false;
		c.removeAll();
		c.addItem("???");	
		repaint();
	}

} // _GraphPanel 
//
//-------------------------------------------------------------------
//
class GraphFrame extends Frame {
	Dimension size = new Dimension(300,300);
  	public Dimension getMinimumSize()  {return size;}
	public Dimension getPreferredSize(){return size;}
	TextArea ta = new TextArea(20,20);
	CardLayout cl;
	Panel pcl;
	PolyGraph pg;

	public GraphFrame(){
		super("Polynomial Coefficients");
		resize(300,300);
		setBackground(new Color(255,255,200));
		setLayout(new GridLayout(1,1,2,2));
		
		pg = new PolyGraph();
		cl=new CardLayout();
		pcl = new Panel();
		pcl.setLayout(cl);
		pcl.add("Data",ta);
		pcl.add("Graph",pg);
		cl.show(pcl,"Data");

		Panel p = new Panel();
		p.setLayout(new BorderLayout(2,2));
		p.add("Center",pcl);
Panel bp = new Panel();
	bp.add(new Button("Data"));
	bp.add(new Button("Graph"));
		bp.add(new Button("Close"));
		p.add("South",bp);
		add(p);
		hide();
	}

	public void init(double []ab){
		ta.setText("");
		for (int i=0;i<ab.length;i++)
			ta.append("X^"+i+" * \t"+ab[i]+"\n");
		pg.set(ab);
	}

	public void paint(Graphics g){
		drawTicks(g);
		// Draw Panel border
		g.setColor(Color.black);
		g.drawRect(0,0,size.width-1,size.height-1);
	}

	public void drawTicks(Graphics g){
		g.setColor(new Color(220,220,200));
		for (int i=0;i*30<size.width;i++)
			g.drawLine(i*30,size.height,i*30,0);

		for (int i=0;i*30<size.height;i++)
			g.drawLine(0,i*30,size.width,i*30);

	}

    	public boolean handleEvent(Event e)  {
      	switch(e.id) {
      	  	case Event.WINDOW_DESTROY : {
      	  	      hide();
		            return (true);
      		}
			default:
				return super.handleEvent(e);
		}
	}

	public boolean action(Event evt, Object arg){
		if (arg.equals("Close"))
			hide();

		if (arg.equals("Graph"))	
			cl.show(pcl,"Graph");
		
		if (arg.equals("Data"))
			cl.show(pcl,"Data");

		return true;
	}
} // _GraphFrame

class PolyGraph extends Panel {
	double x[] = {0};
	int n[];

	public PolyGraph(){
		n = scaleX(x);
	}

	public void set(double ab[]){
		x = ab;
		n = scaleX(x);
		repaint();
	}

	public void paint(Graphics g){
		g.setColor(Color.white);
		g.fillRect(0,0,295,200);
	
		g.setColor(Color.black);
		g.drawLine(0,201,300,201);
		g.drawString("n=1", 3,213);
		g.drawString("n=Max", 250,213);

		g.setColor(Color.blue);
		for (int i=0;i<n.length;i++)
			g.drawLine(5+i*3,200,5+i*3,200-n[i]);
	}
	
	public boolean mouseDown(Event evt, int x, int y){
		System.out.println("X: "+x+" Y: "+y);
		return true;
	}

	public int[] scaleX(double t[]){
		// Get number of terms
		int max = t.length;		
		int n[] = new int[max];

		// Get largest & smallest
		double largest = 0,
			 smallest = 0;

		for (int i=0;i<max;i++){
			if (largest < Math.abs(t[i]))
				largest = Math.abs(t[i]);

			if (smallest > Math.abs(t[i]))
				smallest = Math.abs(t[i]);
		}

		double range = 200/(largest - smallest);
		for (int i=0;i<max;i++)
			n[i] = (int)Math.round(Math.abs(t[i]*range));		
		
		return n;
	}

} // _PolyGraph