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 jia(Complex a,Complex b,Complex c)
  { c.real=a.real+b.real;
	c.image=a.image+b.image;
  }

  public static void jian(Complex a,Complex b,Complex c)
  { c.real=a.real-b.real;
  	c.image=a.image-b.image;
  }
  public static void cheng(Complex a,Complex b,Complex c)
  { double p,q,s;
    c.real=a.real*b.real-a.image*b.image;
    c.image=a.real*b.image+a.image*b.real;
  }
  public static void chu(Complex a,Complex b,Complex c)
  { double w;
    if(Math.abs(b.real)>Math.abs(b.image))
    {w=b.real+b.image*(b.image/b.real);
     c.real=(a.real+a.image*(b.image/b.real))/w;
     c.image=(a.image-a.real*(b.image/b.real))/w;
    }
    else
	{w=b.real*(b.real/b.image)+b.image;
	 c.real=(a.real*(b.real/b.image)+a.image)/w;
	 c.image=(a.image*(b.real/b.image)-a.real)/w;
    }
 }
}

public class Example1_1 extends Applet implements ActionListener
{TextField text1,text2,text3,text4;
 TextArea text5;
 Button button1;
 public void init()
 {text1=new TextField(10);text2=new TextField(10);
  text3=new TextField(10);text4=new TextField(10);
  text5=new TextArea(10,20);
  button1=new Button("計算乘積");
  add(text1);add(text2);add(text3);add(text4);add(button1);add(text5);

  text5.setEditable(false);
  button1.addActionListener(this);
 }
 public void actionPerformed(ActionEvent e)
 {double n1,n2,n3,n4;
  Complex a,b,c;
  if(e.getSource()==button1)
  {n1=Double.valueOf(text1.getText()).doubleValue();
   n2=Double.valueOf(text2.getText()).doubleValue();
   n3=Double.valueOf(text3.getText()).doubleValue();
   n4=Double.valueOf(text4.getText()).doubleValue();
   a=new Complex();b=new Complex();c=new Complex();
   Complex.init(n1,n2,a);Complex.init(n3,n4,b);Complex.init(0,0,c);
   text5.setText("");
   text5.append("復數A=("+a.real+")+("+a.image+")I\n");
   text5.append("復數B=("+b.real+")+("+b.image+")I\n");
   Complex.cheng(a,b,c);
   text5.append("它們的乘積:\nA*B=("+c.real+")+("+c.image+")I\n");

  }
 }

}