# Complex Number Demo : Math « Development Class « Java

Complex Number Demo

```
/*
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 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;
}
}

```

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