Solving the cubic equation using the Complex struct

/// <summary>
        /// Solve ax^3+bx^2+cx+d=0 for x.
        /// Calculation of the 3 roots of a cubic equation according to
        /// http://en.wikipedia.org/wiki/Cubic_function#General_formula_for_roots
        /// Using the complex struct from System.Numerics
        /// Visual Studio 2010, .NET version 4.0
        /// </summary>
        /// <param name="a">real coefficient of x to the 3th power</param>
        /// <param name="b">real coefficient of x to the 2nd power</param>
        /// <param name="c">real coefficient of x to the 1th power</param>
        /// <param name="d">real coefficient of x to the zeroth power</param>
        /// <returns>A list of 3 complex numbers</returns>
        public List<Complex> SolveCubic(double a, double b, double c, double d)
        {
            const int NRoots = 3;

            double SquareRootof3 = Math.Sqrt(3);
            // the 3 cubic roots of 1
            List<Complex> CubicUnity = new List<Complex>(NRoots) 
                        { new Complex(1, 0), new Complex(-0.5, -SquareRootof3 / 2.0), new Complex(-0.5, SquareRootof3 / 2.0) };
            // intermediate calculations
            double DELTA = 18 * a * b * c * d - 4 * b * b * b * d + b * b * c * c - 4 * a * c * c * c - 27 * a * a * d * d;
            double DELTA0 = b * b - 3 * a * c;
            double DELTA1 = 2 * b * b * b - 9 * a * b * c + 27 * a * a * d;
            Complex DELTA2 = -27 * a * a * DELTA;
            Complex C = Complex.Pow((DELTA1 + Complex.Pow(DELTA2, 0.5)) / 2, 1 / 3.0); //Phew...

            List<Complex> R = new List<Complex>(NRoots);
            for (int i = 0; i < NRoots; i++)
            {
                Complex M = CubicUnity[i] * C;
                Complex Root = -1.0 / (3 * a) * (b + M + DELTA0 / M);
                R.Add(Root);
            }
            return R;
        }