ECEF TO LLA C# code

public static double[] convert_ecef_to_wgs84(double x, double y, double z)
        {
            double lon = 0;
            double lat = 0;
            double alt = 0;
            double[] output = new double[3];
            double a = 6378137;
            double e = 8.1819190842622e-2;
            double b = Math.Sqrt(Math.Pow(a, 2) * (1 - Math.Pow(e, 2)));
            double ep = Math.Sqrt((Math.Pow(a, 2) - Math.Pow(b, 2)) / Math.Pow(b, 2));
            double p = Math.Sqrt(Math.Pow(x, 2) + Math.Pow(y, 2));
            double th = Math.Atan2(a * z, b * p);
            lon = Math.Atan2(y, x);
            lat = Math.Atan2((z + Math.Pow(ep, 2) * b * Math.Pow(Math.Sin(th), 3)), (p - Math.Pow(e, 2) * a * Math.Pow(Math.Cos(th), 3)));
            double N = a / (Math.Sqrt(1 - Math.Pow(e, 2) * Math.Pow(Math.Sin(lat), 2)));
            alt = p / Math.Cos(lat) - N;

            lon = lon % (2 * Math.PI);

            bool k = Math.Abs(x) < 1.0 && Math.Abs(y) < 1.0;
            if (k)
                alt = Math.Abs(z) - b;

            lon = lon * 180 / Math.PI;
            lat = lat * 180 / Math.PI;
            output[0] = lon;
            output[1] = lat;
            output[2] = alt;
            return output;

        }