// Complex numbers

package homework1b;

import java.io.*;
import java.util.*;

public class Complex {
    private double re, im;
    
    // constructors
    public Complex() { re = 0.0; im = 0.0; }
    public Complex(double re) { this.re = re; im = 0.0; }
    public Complex(double re, double im)
    { this.re = re; this.im = im; }

    public Complex add(Complex z2)
    {
	Complex temp = new Complex();
	temp.re = re + z2.re;
	temp.im = im + z2.im;
	return temp;
    }

    public Complex sub(Complex z2)
    {
	Complex temp = new Complex();
	temp.re = re - z2.re;
	temp.im = im - z2.im;
	return temp;
    }

    public Complex mul(Complex z2)
    {
	Complex temp = new Complex();
	temp.re = re*z2.re - im*z2.im;
	temp.im = im*z2.re + re*z2.im;
	return temp;
    }

    public Complex div(Complex z2) 
	throws ArithmeticException
    {
	Complex temp = new Complex();
	double den = z2.re*z2.re + z2.im*z2.im;
	if (den == 0.0) throw new ArithmeticException();
	temp.re = (re*z2.re + im*z2.im)/den;
	temp.im = (im*z2.re - re*z2.im)/den;
	return temp;
    }

    public String toString()
    {
	return "(" + re + "," + im + ")";
    }

    public double Re(Complex z)
    { return re; }

    public double Im(Complex z)
    { return im; }

    public Complex Conj()
    {
	Complex temp = new Complex();
	temp.re = re;
	temp.im = -im;
	return temp;
    }

    public boolean equals(Object rhs)
    {
	if (! (rhs instanceof Complex))
	    return false;
	Complex z = (Complex) rhs;
	return z.re == re && z.im == im;
    }

    public void readFromKeyboard() 
    {
	BufferedReader in = new BufferedReader( new
	    InputStreamReader( System.in ));
	String line;
	StringTokenizer str;

	System.out.println("Enter complex number in format (a,b): ");
	try {
	    line = in.readLine();
	    str = new StringTokenizer( line, " ()," );
	    if (str.countTokens() != 2)
		throw new NumberFormatException();
	    re = Double.parseDouble(str.nextToken() );
	    im = Double.parseDouble(str.nextToken() );
	} catch (Exception e) {
	    System.err.println("Error: need a complex number " + 
			       "in format (a,b)"); 
	}
    }

}