Microsoft.Scripting.Utils.MathUtils.Hypot C# (CSharp) Method

        public static double Hypot(double x, double y) {
            //
            // sqrt(x*x + y*y) == sqrt(x*x * (1 + (y*y)/(x*x))) ==
            // sqrt(x*x) * sqrt(1 + (y/x)*(y/x)) ==
            // abs(x) * sqrt(1 + (y/x)*(y/x))
            //

            // Handle infinities
            if (double.IsInfinity(x) || double.IsInfinity(y)) {
                return double.PositiveInfinity;
            }

            //  First, get abs
            if (x < 0.0) x = -x;
            if (y < 0.0) y = -y;

            // Obvious cases
            if (x == 0.0) return y;
            if (y == 0.0) return x;

            // Divide smaller number by bigger number to safeguard the (y/x)*(y/x)
            if (x < y) {
                double temp = y; y = x; x = temp;
            }

            y /= x;

            // calculate abs(x) * sqrt(1 + (y/x)*(y/x))
            return x * System.Math.Sqrt(1 + y * y);
        }