integral.java

数值算法例子,牛顿插值,拉格朗日,三次样条

/*@author 邱宇峰 ,software project031,
 *2004,11,8
 */
import java.awt.*;
import java.awt.event.*;

public class integral extends Frame implements ActionListener{
	static integral frm=new integral();
	static Button b1;
	static Panel pl;
	static Label l;
	static TextField tf;
	public static void main(String[] args){
		pl=new Panel();
		pl.setLayout(new FlowLayout());
		frm.setTitle("拉格朗日逼近法");
		b1=new Button("start");
		l=new Label("Current acreage is");
		tf=new TextField(20);
		pl.add(b1);
		pl.add(l);
		pl.add(tf);
		frm.add(pl,"South");
		frm.setSize(800,500);
 		frm.setLocation(200,200);
		frm.setVisible(true);
		b1.addActionListener(frm);
 		frm.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}
		});
	}
	public void paint(Graphics g){
		double X,Y;
		int x=0;
		g.drawLine(80,300,750,300);
		g.drawLine(90,150,90,300);
		g.drawString("0",90,310);
		g.drawString("6",690,310);
		for(X=0;X<6;X+=0.01){
			Y=Math.sin(X);
			Y=100*(Y/X);
			g.drawString(".",90+x,300-(int)Y);
			x++;
		}
	}
	public void actionPerformed(ActionEvent ae){
		Graphics g=getGraphics();
		g.drawString("Processing...",50,100);
		int n=1;
		double a=0.0,b=6.00,e=0.0001,T0,T1,h;
		h=b-a;
		T0=(h/2)*(1+(Math.sin(b)/b));
		T1=T0/2+(h/2)*Math.abs(Math.sin(a+(h/2))/(a+(h/2)));
		while(Math.abs(T1-T0)>e){
			h=h/2;
			n=2*n;
			T0=T1;
			T1=0;
			for(int k=1;k<=n;k++){
				T1=T1+Math.abs(Math.sin(a+(k-0.5)*h)/(a+(k-0.5)*h));
				for(int i=0;i<500000;i++);
				draw dr=new draw(a+(k-0.5)*h);
				dr.paint(g);
			}
			T1=T0/2+h*T1/2;
			tf.setText(""+T1);
		}
		g.drawString("End",150,100);
	}
}

class draw{
	int index;
	double a;
	public draw(double a){
		this.a=a;
	}
	public draw(int index){
		this.index=index;
	}
	public void paint(Graphics g){
		g.setColor(Color.red);
		g.drawLine(90+(int)(a*100),300,90+(int)(a*100),300-(int)(100*Math.sin(a)/a));	
	}	
}