拉格朗日插值.txt

拉格朗日插值算法

import java.util.*;
import java.awt.*;
import javax.swing.*;
public class chazhi
{
	public static void main(String args[])
	{
		new CH().init(); 
	}
}
class CH extends JFrame
{
	public void init()
	{
		Container con=getContentPane();
		con.add(new MyPanel());
		setSize(1000,400);
		setVisible(true);
		validate();
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
}

class MyPanel extends JPanel implements Runnable 
{
	double x[]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};
	double y[]={1,4,9,16,25,36,49,64,81,100,121,144,169,196,225,256,289,324,361,400};
	double x1,y1;
	int n=20;
	double t,m;
	double px,py;
	public MyPanel()
	{
		new Thread(this).start();
	}

	
	public void run()
	{
		y1=0.0;
		for(px = 0; px < 300; px+=0.1)
			{
				double s = 0;
				for(int k = 0; k < 20; k++)
				{
					double p = y[k];
					for(int j = 0; j < 20; j++)
					{
						
						if(j != k)
						{
							p = p * (px - x[j]) / (x[k] - x[j]);
							
							
						}
						
					}
					s += p;
					try
					{
						Thread.sleep(1);
					}
					catch(InterruptedException Ie1)
					{
						
					}
				}
				py = s;
				repaint();
			}
	}



	public void paintComponent(Graphics g)
	{
		g.setColor(Color.red);
		g.drawLine(100,0,100,400);
		g.drawLine(0,200,200,200);

		g.setColor(Color.green);
		for (int i=0;i<n;i++)
		{
			g.fillOval((int)(x[i]*5+100),(int)((-y[i]+200)),3,3);
		}


		g.setColor(Color.black);
		g.fillOval((int)(px*5+100),(int)(-py+200),2,2);
	}
}