'Use the systems math class
Imports System.Math


    ''' <summary>
    ''' Multiply 2 incoming 4 x 4 matrices and
    ''' </summary>
    ''' <param name="mat1"> A matrix as a 4 x 4 array of doubles. </param>
    ''' <param name="mat2"> A matrix as a 4 x 4 array of doubles. </param>
    ''' <returns> Return a the product as a matrix (4 x 4 array of doubles). </returns>
    ''' <remarks></remarks>
    Public Function MultiplyMatrix(ByVal mat1 As Object, ByVal mat2 As Object) As Object
        Dim result(3, 3) As Double
        Dim i As Integer
        Dim j As Integer
        Dim k As Integer

        For i = 0 To 3
            For j = 0 To 3
                For k = 0 To 3
                    result(i, j) = result(i, j) + (mat1(i, k) * mat2(k, j))
                Next k
            Next j
        Next i

        Return result

    End Function

    ''' <summary>
    ''' Transform a point by multiplying it by a transformation matrix.
    ''' </summary>
    ''' <param name="pt"> A point as a 3 element (X, Y, Z) aray of doubles. </param>
    ''' <param name="mat"> A matrix as a 4 x 4 array of doubles. </param>
    ''' <returns> Return a transformed point as a 3 element aray of doubles. </returns>
    ''' <remarks> For converting points based on Coordinate systems, Rotating, and Scaling.</remarks>
    Public Function TransformPoint(ByVal pt As Object, ByVal mat As Object) As Object
        Dim result(2) As Double

        result(0) = (pt(0) * mat(0, 0)) + (pt(1) * mat(0, 1)) + (pt(2) * mat(0, 2)) + (1 * mat(0, 3))
        result(1) = (pt(0) * mat(1, 0)) + (pt(1) * mat(1, 1)) + (pt(2) * mat(1, 2)) + (1 * mat(1, 3))
        result(2) = (pt(0) * mat(2, 0)) + (pt(1) * mat(2, 1)) + (pt(2) * mat(2, 2)) + (1 * mat(2, 3))

        Return result

    End Function