LinearMatrix.cs

        public static LinearMatrix operator * (LinearMatrix m1, LinearMatrix m2)
        {
            LinearMatrix ret = new LinearMatrix()
            {
                M11 = m1.M11 * m2.M11 + m1.M12 * m2.M21 + m1.M13 * m2.M31,
                M21 = m1.M21 * m2.M11 + m1.M22 * m2.M21 + m1.M23 * m2.M31,
                M31 = m1.M31 * m2.M11 + m1.M32 * m2.M21 + m1.M33 * m2.M31,

                M12 = m1.M11 * m2.M12 + m1.M12 * m2.M22 + m1.M13 * m2.M32,
                M22 = m1.M21 * m2.M12 + m1.M22 * m2.M22 + m1.M23 * m2.M32,
                M32 = m1.M31 * m2.M12 + m1.M32 * m2.M22 + m1.M33 * m2.M32,

                M13 = m1.M11 * m2.M13 + m1.M12 * m2.M23 + m1.M13 * m2.M33,
                M23 = m1.M21 * m2.M13 + m1.M22 * m2.M23 + m1.M23 * m2.M33,
                M33 = m1.M31 * m2.M13 + m1.M32 * m2.M32 + m1.M33 * m2.M33
            };

            return ret;
        }