MathUtilities.java

/*
Asked by Brian ( http://profile.yahoo.com/FZ6MESRR27BQISRYONDQEPJ5MM ) in Yahoo!Answers on June 20, 2013:

Inside a class MathUtilities, write a method calculateRoots which takes as input 3 doubles, representing the quadratic, linear, and constant...
*/
public class MathUtilities
{
    public ComplexNumber[] calculateRoots( double a, double b, double c) {
        ComplexNumber[] roots;
        double B = (0 == b) ? 0 : -b;   // avoid using -0.0 when b is zero
        double discriminant = b*b - 4*a*c;
        if (0 == discriminant) {
            roots = new ComplexNumber[ 1 ];
            roots[0] = new ComplexNumber(B / (2*a), 0);
        }
        else if (0 < discriminant) {
            roots = new ComplexNumber[ 2 ];
            roots[0] = new ComplexNumber(
                (B - Math.sqrt( discriminant )) / (2*a), 0
            );
            roots[1] = new ComplexNumber(
                (B + Math.sqrt( discriminant )) / (2*a), 0
            );
        }
        else {
            roots = new ComplexNumber[ 2 ];
            roots[0] = new ComplexNumber(
                B / (2*a), -Math.sqrt( -discriminant )/ (2*a)
            );
            roots[1] = new ComplexNumber(
                B / (2*a), Math.sqrt( -discriminant )/ (2*a)
            );
        }
        return roots;
    }

    public class ComplexNumber
    {
        private double real;
        private double imaginary;
        public ComplexNumber() {
            this(0, 0);
        }
        public ComplexNumber( double r, double i) {
            real = r;
            imaginary = i;
        }
        public double[] get() {
            double[] complex = new double[2];
            complex[0] = real;
            complex[1] = imaginary;
            return complex;
        }
        public double getReal() {
            return real;
        }
        public double getImaginary() {
            return imaginary;
        }
    }
}