example1_9.java

清华大学2002年出版的《科学与工程数值计算算法Java》配套源码

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

class Complex
{ double real,image;
  public static void init(double a,double b,Complex c)
  {c.real=a;c.image=b;}
 public static void Cos(Complex a)
 { double x,y;
   y=Math.exp(a.image);x=a.real;
   a.real=Math.cos(x)*(y+1.0/y)/2;
   a.image=Math.sin(x)*(1.0/y-y)/2;
 }
}

public class Example1_9 extends Applet implements ActionListener
{TextField text1,text2;
 TextArea text3;
 Button button1;
 public void init()
 {text1=new TextField(10);text2=new TextField(10);text3=new TextArea(10,50);
  button1=new Button("计算余弦");
  add(text1);add(text2);add(button1);add(text3);
  text3.setEditable(false);
  button1.addActionListener(this);
 }
 public void actionPerformed(ActionEvent e)
 {double n1,n2;
  Complex a;
  if(e.getSource()==button1)
  {n1=Double.valueOf(text1.getText()).doubleValue();
   n2=Double.valueOf(text2.getText()).doubleValue();
   a=new Complex();Complex.init(n1,n2,a);
   text3.setText("");
   text3.append("复数A=("+a.real+")+("+a.image+")I\n");
   Complex.Cos(a);
   text3.append("它的余弦:\nCosA=("+a.real+")+("+a.image+")I\n");
   }
 }

}