|
/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.com/javaexamples3.
*/
/**
* This class represents complex numbers, and defines methods for performing
* arithmetic on complex numbers.
*/
public class ComplexNumber {
// These are the instance variables. Each ComplexNumber object holds
// two double values, known as x and y. They are private, so they are
// not accessible from outside this class. Instead, they are available
// through the real() and imaginary() methods below.
private double x, y;
/** This is the constructor. It initializes the x and y variables */
public ComplexNumber(double real, double imaginary) {
this.x = real;
this.y = imaginary;
}
/**
* An accessor method. Returns the real part of the complex number. Note that
* there is no setReal() method to set the real part. This means that the
* ComplexNumber class is "immutable".
*/
public double real() {
return x;
}
/** An accessor method. Returns the imaginary part of the complex number */
public double imaginary() {
return y;
}
/** Compute the magnitude of a complex number */
public double magnitude() {
return Math.sqrt(x * x + y * y);
}
/**
* This method converts a ComplexNumber to a string. This is a method of
* Object that we override so that complex numbers can be meaningfully
* converted to strings, and so they can conveniently be printed out with
* System.out.println() and related methods
*/
public String toString() {
return "{" + x + "," + y + "}";
}
/**
* This is a static class method. It takes two complex numbers, adds them, and
* returns the result as a third number. Because it is static, there is no
* "current instance" or "this" object. Use it like this: ComplexNumber c =
* ComplexNumber.add(a, b);
*/
public static ComplexNumber add(ComplexNumber a, ComplexNumber b) {
return new ComplexNumber(a.x + b.x, a.y + b.y);
}
/**
* This is a non-static instance method by the same name. It adds the
* specified complex number to the current complex number. Use it like this:
* ComplexNumber c = a.add(b);
*/
public ComplexNumber add(ComplexNumber a) {
return new ComplexNumber(this.x + a.x, this.y + a.y);
}
/** A static class method to multiply complex numbers */
public static ComplexNumber multiply(ComplexNumber a, ComplexNumber b) {
return new ComplexNumber(a.x * b.x - a.y * b.y, a.x * b.y + a.y * b.x);
}
/** An instance method to multiply complex numbers */
public ComplexNumber multiply(ComplexNumber a) {
return new ComplexNumber(x * a.x - y * a.y, x * a.y + y * a.x);
}
}
|