newton.java

数值算法,牛顿算法源码,动态演示过程,JAVA源码

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


public class Newton {
        
    /**
     * Creates a new instance of <code>Newton</code>.
     */
    public Newton() {
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        new newFrame().init();
        
    }
}


class newFrame extends JFrame
{
    public void init()  
    {
    	MyPanel hello=new MyPanel();
        getContentPane().add(hello);
        hello.thread.start();

        //以下代码设置JFrame窗体的外观
        setSize(400,400);
        setLocation(200,200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
}

class MyPanel extends JPanel implements Runnable
{
    Thread thread;
    
    double xpoint[],ypoint[];
    double x[]={1.0,2.0,3.0,4.0,5.0,6.0,7.0};
    //double y[]={1.0,1.414214,1.732051,2.0,2.236068,2.449490,2.645751};
    double y[]={0.1,0.4,0.9,1.6,2.5,3.6,4.9};
    double a[];
    double p;
    
    int N=7;
    int num;
    public MyPanel() 
    {
    	xpoint=new double[100];
    	ypoint=new double[100];
        setSize(500, 500);  
        	                 
        thread=new Thread(this);
        
        a=new double[7];
        ///////////////////////////以下计算差商值保存在数组a中
        for(int i=0;i<N;i++)
        {
        	a[i]=y[i];
        }
        for(int k=1;k<N;k++)
        {
        	for(int j=N-1;j>=k;j--)
        	{
        		a[j]=(a[j]-a[j-1])/(x[j]-x[j-k]);
        	}
        }
        
        ////////////////////////////以下计算牛顿插值
        for(int i=0,k=-50;i<100;i++)
        {
        	xpoint[i]=k;
        	
        	p=a[N-1];
        	for(int j=N-1;j>=0;j--)
        	{
        		p=p*(xpoint[i]-x[j])+a[j];
        	}
        	
        	k++;
        	ypoint[i]=p;
        
        } 
    }

    public void run()  
    {
    	for(num=2;num<99;num++)          //显示前num个点
    	{
    		repaint();
    		try{
    			thread.sleep(50);		
    		}
    		catch(InterruptedException e)
    		{
    		}
    	}
    	
    }

     public void paintComponent(Graphics g)   
     {
         g.setColor(Color.white);              
         g.clearRect(0, 0, 400, 440);   

         g.setColor(Color.red);     
         g.drawLine(0, 200, 400, 200);   
         g.drawLine(200, 400, 200, 0); 
         
         g.translate(200,200);
         
         g.setColor(Color.blue);
         
         for(int i=0;i<num;i++)
         {
         	g.drawLine((int)xpoint[i],-(int)(ypoint[i]),(int)xpoint[i+1],-(int)(ypoint[i+1]));
         }
         
         g.setColor(Color.black);
         g.drawString("x[ ]={1.0,2.0,3.0,4.0,5.0,6.0,7.0}",-190,-180);
         g.drawString("y[ ]={0.1,0.4,0.9,1.6,2.5,3.6,4.9}",-190,-160);
         
         g.drawString("牛顿插值算法",-180,-100);
         //g.drawString(""+xpoint[60]+"    "+ypoint[60],-180,-50);
     }

}