// Copyright 哲猫.
/* 
 台形公式による数値積分
*/ 
/* <applet code="Ex061030a.class" width=300 height=100> </applet> */

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

public class Ex061030a extends JApplet implements ActionListener{
	Func061030a f; 
	JLabel lb;
	JComboBox cb;
	String cbl[]={"10","100","1000","10000","100000","1000000"};
	double val = 0.0;	
	public void init(){
		Container cp = getContentPane();
  	JPanel pl = new JPanel();
  	pl.setBackground(Color.black);
    pl.setLayout(null);
    cb = new JComboBox(cbl);
    cb.setBounds(0,0,80,20);
    cb.setSelectedIndex(0);
    cb.addActionListener(this);
		pl.add(cb);	
		f = new Func061030a();
		lb = new JLabel();
		lb.setForeground(Color.yellow);
		lb.setFont(new Font("Dialog", Font.PLAIN, 20));
		lb.setBounds(90,20,210,60);
  	pl.add(lb);
  	cp.add(pl); 
	}
	
	public void actionPerformed(ActionEvent event){
		int num = cb.getSelectedIndex();
		int sl=0;
		switch(num){
			case 0 : sl=10 ; break;
			case 1 : sl=100 ; break;
			case 2 : sl=1000 ; break;
			case 3 : sl=10000 ; break;
			case 4 : sl=100000 ; break;
			case 5 : sl=1000000 ; break;
		}
		val = nCalc.trapezium(f,sl,0.0,1.0);
		lb.setText(""+val);
	}	
}

class Func061030a implements nCalc.Function{
	public double func(double x){
		return(4/(1+x*x));
	}
}