golddiv.java

黄金分割的程序实了例

import java.awt.*;
import java.awt.event.*;
/**
 * 
 *
 * @author  bobo
 * @version 1.00 06/12/04
 */
public class GoldDiv{
       public static double Pi=3.1415926;
       public static void main(String args[]){
              Frame f=new Frame("黄金分割搜索");
              Button b1=new Button("                draw cosX               ");
              Button b2=new Button("搜索Xmax=cosX");
              Panel p=new Panel();
              p.setBackground(Color.yellow);
              f.add(p,"South");
              p.add(b1);
              p.add(b2);
              f.setBounds(100,100,600,400);
              Listener1 bh1=new Listener1(f);
              Listener2 bh2=new Listener2(f);
              Listener3 bh3=new Listener3(f);
              f.addWindowListener(bh1);
              b1.addActionListener(bh2);
              b2.addActionListener(bh3);
              f.setVisible(true);
              }
        }


class Listener1 extends WindowAdapter{
      Listener1(Frame f){
                this.f=f;
                }
      private Frame f;
      public void windowClosing(WindowEvent e){
                 System.exit(0);
                 }
      }



class Listener2 implements ActionListener    {
      Listener2(Frame f){
                this.f=f;
                }
      private Frame f;
      public void actionPerformed(ActionEvent e){
                  Graphics g=f.getGraphics();
                  g.drawLine(10,250,490,250);
                  g.drawLine(250,100,250,340);
                  g.drawString("0",242,262);
                  g.drawString("x",490,262);
                  g.drawString("y",254,105);
                  g.drawLine(250,100,248,104);
                  g.drawLine(250,100,252,104);
                  g.drawLine(490,250,486,248);
                  g.drawLine(490,250,486,252);
                  g.drawString("1",242,150);
                  g.drawString("-π/2",98,262);
                  g.drawString("π/2",382,262);
                  for(int x=10;x<=490;x++){
                        double double_y=250-(Math.cos((x-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi);
                        f.getGraphics().drawString(".",x,(int)double_y);
                        for(int i=0;i<100000;i++);
                        }
                  g.drawString("y=cos x",395,240);                                             
                  }
      } 

class Listener3 implements ActionListener{
      Listener3(Frame f){ 
                this.f=f;
                }
      private Frame f;
      private double x1,y1,x2,y2,a,b;
      private int count=0;
      public void actionPerformed(ActionEvent e){
                  a=100.00;b=400.00;
                  x1=a+0.328*(b-a);x2=a+0.618*(b-a);
                  y1=250-(Math.cos((x1-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi);
                  y2=250-(Math.cos((x2-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi);
                  while(count<=15){
                      if(y1>y2){
                          Graphics g=f.getGraphics();
                          g.setColor(Color.blue);
                          g.drawLine((int)((x1+x2)/2),250, (int)((x1+x2)/2), (int)(250-(Math.cos((((x1+x2)/2)-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi)));
                          for(int i=0;i<10000000;i++);
                          a=x1;x1=x2;y1=y2;
                          x2=a+0.618*(b-a);
                          y2=250-(Math.cos((x2-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi);
                          }
                      else{
                          Graphics g=f.getGraphics();
                          g.setColor(Color.blue);
                          g.drawLine((int)((x1+x2)/2),250, (int)((x1+x2)/2), (int)(250-(Math.cos((((x1+x2)/2)-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi)));
                          for(int i=0;i<10000000;i++);
                          b=x2;x2=x1;y2=y1;
                          x1=a+0.328*(b-a);
                          y1=250-(Math.cos((x1-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi);
                          }
                      count++;
                      if((int)x1==250||(int)x2==250){
                          Graphics g=f.getGraphics();
                          g.setColor(Color.green);
                          g.drawLine(250,250,260,260);                    
                          g.drawString("x=0时y取得最大值1",263,262);
                          Graphics h=f.getGraphics();
                          h.setColor(Color.pink);
                          h.drawLine(250,250, 250, (int)(250-(Math.cos((250-250)*(GoldDiv.Pi/300)))*(300/GoldDiv.Pi)));
                          break;                                                           
                          }
                      }
                  }
                    
                }