Matrix multiplication in VBA using arrays

NewVBA · June 11th, 2006, 06:31 AM

Using VBA, I multiplied 2 arrays as below:

Dim X(1 To 3, 1 To 8) As Single
Dim Y(1 To 3, 1 To 8) As Single
Dim Z() As Single

X=.....
Y=.....

Z = Application.WorksheetFunction.MMult(X, Y)

The matrix multiplication did not work with Z As Single or Double only when it was Variant. I got a Type mismatch error, a similar thing happened if I defined the dimensions of Z (correctly). Why is this?

Is there a way round this if I want to multiply 2-D arrays using Mmult or some other method?

Variant arrays take up too much memory.

Many Thanks

jrogers · June 26th, 2006, 03:15 PM

I had a bit of a play around and came out with the following... I know this may not be an exact solution for you, but I hope you can addapt the code to help

Code:

    Dim X(1 To 8, 1 To 8) As Single
    Dim Y(1 To 8, 1 To 8) As Single
    Dim z(1 To 8, 1 To 8) As Single

' generating values for x and y
' enter your own values
    For a = 1 To 8
        For b = 1 To 8
            X(a, b) = Int(Rnd() * 10)
        Next
    Next

    For b = 1 To 8
        For a = 1 To 8
            Y(a, b) = Int(Rnd() * 10)
        Next
    Next


' populating z
    For a = 1 To 8
        For b = 1 To 8
            z(a, b) = Application.WorksheetFunction.MMult(X, Y)(a, b)
        Next
    Next