example1_6.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 double abs(Complex a)
  {double x,y,r;
   x=Math.abs(a.real);y=Math.abs(a.image);
   if(x>y)r=x*Math.sqrt(1+(y/x)*(y/x));
   else r=y*Math.sqrt(1+(x/y)*(x/y));
   return r;
  }

 public static void Ln(Complex a)
 {double r,Pi=Math.PI,sita;
  r=Complex.abs(a);
  if(r!=0)
  {if(a.image==0)
    {if (a.real>=0)sita=0;
     else sita=Pi;}
  else if(a.real==0)
    {if(a.real>0)sita=Pi/2;
     else sita=-Pi/2;}
  else {if (a.real>0) sita=Math.atan(a.image/a.real);
        else sita=(Math.atan(a.image/a.real)+Pi);}
  a.real=Math.log(r);a.image=sita;}
 }
}

public class Example1_6 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("计算自然对数");
  add(text1);add(text2);add(button1);add(text3);
  text3.setEditable(false);
  button1.addActionListener(this);
 }
 public void actionPerformed(ActionEvent e)
 {double n1,n2,n3;
  Complex a,b;
  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.Ln(a);
   text3.append("它的自然对数主值为：\n");
   text3.append("("+a.real+")+("+a.image+")I\n");
  }
}
}