A Class to Test Complex Numbers

package com.darwinsys;
 
/*
 * 3.0+5.0i 3.0+5.0i.getReal() = 3.0 3.0+5.0i + 2.0-2.0i = 5.0+3.0i 3.0+5.0i + 2.0-2.0i = 5.0+3.0i
 * 3.0+5.0i 2.0-2.0i = 16.0+4.0i -0.5+2.0i
 */
 
/**
 * A class to test Complex Numbers.
 * 
 * @author Ian F. Darwin, http://www.darwinsys.com/
 * @version $Id: ComplexDemo.java,v 1.6 2004/05/13 22:28:59 ian Exp $
 */
public class ComplexDemo {
    /** The program */
    public static void main(String[] args) {
	Complex c = new Complex(3, 5);
	Complex d = new Complex(2, -2);
	System.out.println(c);
	System.out.println(c + ".getReal() = " + c.getReal());
	System.out.println(c + " + " + d + " = " + c.add(d));
	System.out.println(c + " + " + d + " = " + Complex.add(c, d));
	System.out.println(c + " * " + d + " = " + c.multiply(d));
	System.out.println(Complex.divide(c, d));
    }
}
 
/**
 * A class to represent Complex Numbers. A Complex object is immutable once created; the add,
 * subtract and multiply routines return newly-created Complex objects containing the results.
 * 
 * @author Ian F. Darwin, inspired by David Flanagan.
 * @version $Id: Complex.java,v 1.3 2004/05/13 22:28:59 ian Exp $
 */
class Complex {
    /** The real part */
    private double r;
    /** The imaginary part */
    private double i;
 
    /** Construct a Complex */
    Complex(double rr, double ii) {
	r = rr;
	i = ii;
    }
 
    /**
     * Display the current Complex as a String, for use in println() and elsewhere.
     */
    public String toString() {
	StringBuffer sb = new StringBuffer().append(r);
	if (i > 0)
	    sb.append('+'); // else append(i) appends - sign
	return sb.append(i).append('i').toString();
    }
 
    /** Return just the Real part */
    public double getReal() {
	return r;
    }
 
    /** Return just the Real part */
    public double getImaginary() {
	return i;
    }
 
    /** Return the magnitude of a complex number */
    public double magnitude() {
	return Math.sqrt(r * r + i * i);
    }
 
    /**
     * Add another Complex to this one
     */
    public Complex add(Complex other) {
	return add(this, other);
    }
 
    /**
     * Add two Complexes
     */
    public static Complex add(Complex c1, Complex c2) {
	return new Complex(c1.r + c2.r, c1.i + c2.i);
    }
 
    /**
     * Subtract another Complex from this one
     */
    public Complex subtract(Complex other) {
	return subtract(this, other);
    }
 
    /**
     * Subtract two Complexes
     */
    public static Complex subtract(Complex c1, Complex c2) {
	return new Complex(c1.r - c2.r, c1.i - c2.i);
    }
 
    /**
     * Multiply this Complex times another one
     */
    public Complex multiply(Complex other) {
	return multiply(this, other);
    }
 
    /**
     * Multiply two Complexes
     */
    public static Complex multiply(Complex c1, Complex c2) {
	return new Complex(c1.r * c2.r - c1.i * c2.i, c1.r * c2.i + c1.i * c2.r);
    }
 
    /**
     * Divide c1 by c2.
     * 
     * @author Gisbert Selke.
     */
    public static Complex divide(Complex c1, Complex c2) {
	return new Complex((c1.r * c2.r + c1.i * c2.i) / (c2.r * c2.r + c2.i * c2.i), (c1.i * c2.r - c1.r * c2.i)
		/ (c2.r * c2.r + c2.i * c2.i));
    }
 
    /*
     * Compare this Complex number with another
     */
    public boolean equals(Object o) {
	if (!(o instanceof Complex))
	    throw new IllegalArgumentException("Complex.equals argument must be a Complex");
	Complex other = (Complex) o;
	return r == other.r && i == other.i;
    }
 
    /*
     * Generate a hashCode; not sure how well distributed these are.
     */
    public int hashCode() {
	return (int) (r) | (int) i;
    }
}