Complex.java

package android.ilus.spltest.android.ilus;

public class Complex
{
    private final double re; // the real part
    private final double im; // the imaginary part

    // create a new object with the given real and imaginary parts
    public Complex(double real, double imag)
    {
        re = real;
        im = imag;
    }

    // return a string representation of the invoking Complex object
    public String toString()
    {
        if (im == 0)
            return re + "";
        if (re == 0)
            return im + "i";
        if (im < 0)
            return re + " - " + (-im) + "i";
        return re + " + " + im + "i";
    }

    // return abs/modulus/magnitude and angle/phase/argument
    public double abs()
    {
        return Math.hypot(re, im);
    } // Math.sqrt(re*re + im*im)

    public double phase()
    {
        return Math.atan2(im, re);
    } // between -pi and pi

    // return a new Complex object whose value is (this + b)
    public Complex plus(Complex b)
    {
        Complex a = this; // invoking object
        double real = a.re + b.re;
        double imag = a.im + b.im;
        return new Complex(real, imag);
    }

    // return a new Complex object whose value is (this - b)
    public Complex minus(Complex b)
    {
        Complex a = this;
        double real = a.re - b.re;
        double imag = a.im - b.im;
        return new Complex(real, imag);
    }

    // return a new Complex object whose value is (this * b)
    public Complex times(Complex b)
    {
        Complex a = this;
        double real = a.re * b.re - a.im * b.im;
        double imag = a.re * b.im + a.im * b.re;
        return new Complex(real, imag);
    }

    // scalar multiplication
    // return a new object whose value is (this * alpha)
    public Complex times(double alpha)
    {
        return new Complex(alpha * re, alpha * im);
    }

    // return a new Complex object whose value is the conjugate of this
    public Complex conjugate()
    {
        return new Complex(re, -im);
    }

    // return a new Complex object whose value is the reciprocal of this
    public Complex reciprocal()
    {
        double scale = re * re + im * im;
        return new Complex(re / scale, -im / scale);
    }

    // return the real or imaginary part
    public double re()
    {
        return re;
    }

    public double im()
    {
        return im;
    }

    // return a / b
    public Complex divides(Complex b)
    {
        Complex a = this;
        return a.times(b.reciprocal());
    }

    // return a new Complex object whose value is the complex exponential of
    // this
    public Complex exp()
    {
        return new Complex(Math.exp(re) * Math.cos(im), Math.exp(re)
                * Math.sin(im));
    }

    // return a new Complex object whose value is the complex sine of this
    public Complex sin()
    {
        return new Complex(Math.sin(re) * Math.cosh(im), Math.cos(re)
                * Math.sinh(im));
    }

    // return a new Complex object whose value is the complex cosine of this
    public Complex cos()
    {
        return new Complex(Math.cos(re) * Math.cosh(im), -Math.sin(re)
                * Math.sinh(im));
    }

    // return a new Complex object whose value is the complex tangent of this
    public Complex tan()
    {
        return sin().divides(cos());
    }

    // a static version of plus
    public static Complex plus(Complex a, Complex b)
    {
        double real = a.re + b.re;
        double imag = a.im + b.im;
        Complex sum = new Complex(real, imag);
        return sum;
    }

    // sample client for testing
    public static void main(String[] args)
    {
        Complex a = new Complex(5.0, 6.0);
        Complex b = new Complex(-3.0, 4.0);

        System.out.println("a            = " + a);
        System.out.println("b            = " + b);
        System.out.println("Re(a)        = " + a.re());
        System.out.println("Im(a)        = " + a.im());
        System.out.println("b + a        = " + b.plus(a));
        System.out.println("a - b        = " + a.minus(b));
        System.out.println("a * b        = " + a.times(b));
        System.out.println("b * a        = " + b.times(a));
        System.out.println("a / b        = " + a.divides(b));
        System.out.println("(a / b) * b  = " + a.divides(b).times(b));
        System.out.println("conj(a)      = " + a.conjugate());
        System.out.println("|a|          = " + a.abs());
        System.out.println("tan(a)       = " + a.tan());
    }

}