adapt.java

数值算法

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.Panel;
import java.io.*;
public class Adapt extends Frame implements ActionListener
{
	private float a=0.5f,b=5.50f,e=0.01f,h;
	Button bb;
	public Adapt()
	{	
		setLayout(new FlowLayout(FlowLayout.LEFT));
		bb=new Button("DRAW");
		add(bb);
		setSize(700,500);
		setBackground(Color.white);
		bb.addActionListener(this);
	}
	
		
	public void paint(Graphics g)
	{
		float i,x;
		g.drawLine(300,50,300,450);
		g.drawLine(10,250,700,250);
		for(i=a;i<=b;i=i+0.01f)
		{	
			x=i-3.0f;
			g.drawLine((int)(i*100),(int)(250-Fac(x)*100),(int)(i*100+1),(int)(250-Fac(x+0.01f)*100));
		}	 
	}
	public float Fac(float x)//use after multiply 100,out same
	{		
		float y;
		if(x==0)y=0;
		else
		{
			y=(float)(Math.sin(x)/x);
		}
		return y;
	}
	public void Scrawl(float AA,float HH)
	{
		
		int i=0,x1,x2,y1,y2;
		float x;
		Graphics g = getGraphics();
		for(int j=0;j<500000000;j++){}
		for(i=1;;i++)
		{
			x=AA+i*HH;
			if(x>=b-3f)break;	
			x1=(int)(x*100)+300;
			y1=(int)(250-Fac(x)*100);
			x2=(int)(x*100)+300;
			y2=250;
			g.drawLine(x1,y1,x2,y2);
		}
	}
	public void Metic(float A,float B,float E)
	{
		float H;
		float T0,T1;
		A=A-3f;
		B=B-3f;
		H=B-A;
		T0=H*(Fac(A)+Fac(B))/2;
		T1=T0/2+H*Fac(A+H/2)/2;
		int n=1;
		int k=1;
		while(Math.abs(T1-T0)>=E)
		{
			H=H/2;
		
			n=2*n;
			T0=T1;
			T1=0;
			for(k=1;k<=n;k++)
			{
				T1=T1+Fac((float)(A+(k-0.5)*H));
			}
			T1=T0/2+H*T1/2;
			Scrawl(A,H);
		}
	}
	public void actionPerformed(ActionEvent eve)
	{
		if(eve.getSource()==bb)
		{
			Metic(a,b,e);
			System.out.println("completed");
		}
	}
	
	public static void main(String[] args)throws IOException
	{
		Adapt fuck=new Adapt();
		fuck.setVisible(true);
	/*	InputStreamReader reader=new InputStreamReader(System.in);
		BufferedReader input=new BufferedReader(reader);
		String text=input.readLine();
		a=new Float(text).floatValue();
		text=input.readLine();
		b=new Float(text).floatValue();
		text=input.readLine();
		e=new Float(text).floatValue();*/
	}
}