牛顿插值.txt

牛顿插值算法

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 a[]=new double[20];
	double x1,y1;
	int n=20;
	double t,m;
	double nx=0,ny=0;
	public MyPanel()
	{
		new Thread(this).start();
	}

	
	public void run()
	{
		for(int j = 0; j < 20; j++)
			{
				a[j] = y[j];
			}
			
			for(int k = 1; k <20; k++)
			{
				for(int j = 19; j >= k; j--)
				{
					a[j] = (a[j] - a[j - 1])/(x[j] - x[j - k]);
				}
			}
			
			for(nx = 0; nx < 300; nx += 0.1)
			{
				ny = a[19];
				for(int ni = 18; ni >= 0; ni--)
				{
					
					ny = ny * (nx - x[ni]) + a[ni];	
					try
					{
						Thread.sleep(1);
					}
					catch(InterruptedException Ie2)
					{
						
					}
					
				}
				m=ny;
				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)(nx*5+100),(int)(-m+200),2,2);
	}
}