Plus and PlusEquals methods can be used for matrix addition. Unlike the Plus Method, the PlusEquals method does not create a new matrix but instead adds to current matrix elements.

In the same way, Minus and MinusEquals methods can be used for matrix subtraction.

Matrix addition and subtraction is possible only between matrices of the same size.

Times method performs matrix multiplication. TimesScalar multiplies matrix elements by a scalar value.

'Declare 2 matrices and fill them with random values
Dim A As Matrix, B As Matrix
Set A = New Matrix
A.Size 4, 4
A.FillRandom
Set B = New Matrix
B.Size 4, 4
B.FillRandom
'Print the result A + B
Debug.Print "A + B ="
Debug.Print A.Plus(B).GetString
'Print the result A - B
Debug.Print "A - B ="
Debug.Print A.Minus(B).GetString
'Print the result A * B
Debug.Print "A * B ="
Debug.Print A.Times(B).GetString

Inverse and Transpose methods return the matrix inverse and transpose respectively. Not all matrices are invertible. It is a good practice to use error handling to trap the error that would result from this situation.

On Error Resume Next
Set B = A.Inverse
If Err.Number = 1306 + vbObjectError Then
    'put your error handling code here
    Debug.Print "Singular Matrix"
End If
Debug.Print "Inverse of A = "
Debug.Print A.GetString 

Using the Plus, Minus, Times, TimesScalar, Inverse and Transpose methods leaves original matrix unaffected. This gives you the choice to preserve the original matrix for later use or to replace current instance:

Set B = A.Inverse
'Matrix B contains the inverse of matrix A, while A remains unaffected.
Set A = A.Inverse
'Matrix variable A now contains the inverse of the original matrix.

Finally the Determinant method computes and returns the determinant of current matrix.

Debug.Print A.Determinant

What is next:

Matrix Decompositions

See Also:

Referencing ShortName 3.1 | Declaring Matrices | Matrix Properties and Methods | Matrices and Arrays | Eigenvalues and Eigenvectors