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Using O-Matrix as a Math Analysis Library for VBA

Description
For the VBA developer, O-Matrix can be used as a numerical analysis library to expand the mathematical analysis capabilities of VBA. This example defines a function that uses O-Matrix to calculate the rank of a matrix and uses this function to calculate the rank of a matrix defined in a VBA program.

Example
Start O-Matrix. Start Excel and create a new Excel Link workbook. In Excel press Alt-F11 to invoke the VBA editor. Right-click on the Modules folder and select 'Insert | Module'. Paste the following code into the new module.

Function rank(VBMatrix As Variant) As Integer
    Dim status As String
    
    Call OMPutVar("VBMatrix", VBMatrix)
    status = OMEval("vbRank = rank(VBMatrix)")
    If status <> "OM_OK" Then
        MsgBox ("Unable to execute rank command")
        Exit Function
    End If
    
    rank = OMGetVar("vbRank")
End Function

Sub TestRank()
    Dim r(1, 1) As Single
    Dim status As String
    
    r(0, 0) = 1#
    r(0, 1) = 0#
    r(1, 0) = 0#
    r(1, 1) = 2#
    
    status = OMOpen()
    MsgBox ("Rank of sample matrix = " & Str(rank(r)))
End Sub

Press the F5 key to run the example. Excel will post a dialog displaying the rank of the sample matrix.