// The copyright of this program is reserved by �N�L.
/* 
Tschebyscheff �̑�����
*/ 

/* <applet code="Ex061009a.class" width=300 height=300> </applet> */

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Ex061009a extends JApplet implements ActionListener{
	boolean flag=false;
	double h=0.01;
  JComboBox cb;
  int num = 1;
  String cbl[]={"k=0","k=1","k=2","k=3","k=4","k=5","k=6","k=7","k=8","k=9","k=10"};
	public void init(){
		Container cp = getContentPane();
		JPanel pl = new JPanel();
		pl.setBackground(Color.black);
    pl.setLayout(null);
    cb = new JComboBox(cbl);
    cb.setBounds(0,0,60,20);
    cb.setSelectedIndex(0);
    cb.addActionListener(this);
		pl.add(cb);
		cp.add(pl);
	}
	
  public void actionPerformed(ActionEvent event){
		num = cb.getSelectedIndex(); 
		flag=true;
		repaint();
	}
	
	public void paint(Graphics g){
		super.paint(g);
		g.setColor(Color.blue);
		g.drawLine(50,150,250,150);
		g.drawLine(150,50,150,250);
		g.drawRect(50,50,200,200);
		g.setColor(Color.red);
		g.setFont(new Font("Dialog", Font.PLAIN,20));
		g.drawString("-1",30,160);
		g.drawString("1",260,160);
		g.drawString(" 1",140,40);
		g.drawString("-1",140,270);
		if(flag==true)
			for(double x=-1.0;x<1.0;x+=h){
		  	g.setColor(Color.green);
	 	  	g.drawLine((int)(x*100+150),150-(int)(tschebyscheff(num,x)*100),(int)((x+h)*100+150),150-(int)(tschebyscheff(num,x+h)*100));
			}	
	}
			
	public double tschebyscheff(int n,double x){
		if(n==0)
			return(1.0);
		if(n==1)
			return(x);
		return(tschebyscheff(n-1,x)*2.0*x-tschebyscheff(n-2,x));		
	}
}