Accord.Imaging.MatrixH.Multiply C# (CSharp) Method

        public MatrixH Multiply(MatrixH matrix)
        {
            float na = elements[0] * matrix.elements[0] + elements[1] * matrix.elements[3] + elements[2] * matrix.elements[6];
            float nb = elements[0] * matrix.elements[1] + elements[1] * matrix.elements[4] + elements[2] * matrix.elements[7];
            float nc = elements[0] * matrix.elements[2] + elements[1] * matrix.elements[5] + elements[2];

            float nd = elements[3] * matrix.elements[0] + elements[4] * matrix.elements[3] + elements[5] * matrix.elements[6];
            float ne = elements[3] * matrix.elements[1] + elements[4] * matrix.elements[4] + elements[5] * matrix.elements[7];
            float nf = elements[3] * matrix.elements[2] + elements[4] * matrix.elements[5] + elements[5];

            float ng = elements[6] * matrix.elements[0] + elements[7] * matrix.elements[3] + matrix.elements[6];
            float nh = elements[6] * matrix.elements[1] + elements[7] * matrix.elements[4] + matrix.elements[7];
            float ni = elements[6] * matrix.elements[2] + elements[7] * matrix.elements[5] + 1f;

            return new MatrixH(na, nb, nc, nd, ne, nf, ng, nh, ni);
        }

        public void MultiplyTest()
        {
            MatrixH A = new MatrixH();
            MatrixH B = new MatrixH();

            MatrixH expected = new MatrixH();
            MatrixH actual = A.Multiply(B);

            Assert.IsTrue(Accord.Math.Matrix.IsEqual(
                expected.Elements, actual.Elements));


            double[,] a = 
            {
                { 2, 3, 1 },
                { 2, 1, 7 },
                { 1, 2, 2 }
            };

            double[,] b = 
            {
                {  1,  3,  1 },
                { -2,  1, -4 },
                {  1, -1,  3 }
            };

            A = new MatrixH(a);
            B = new MatrixH(b);

            actual = A.Multiply(B);
            expected = new MatrixH(Accord.Math.Matrix.Multiply(a, b));

            Assert.IsTrue(Accord.Math.Matrix.IsEqual(
                (double[,])actual, (double[,])expected,
                0.001));
        }