Question

My user defined function always returns ‘A value used in the formula is of the wrong data type’ (I am passing cell ranges to the function). I’ve searched lots of threads and am quite sure my code should work:

Function SortAndEvaluate(ByRef Probs() As Variant, ByRef ResidualProbs() As Variant, ByRef Costs() As Variant)
    Dim Temp As Double
    Dim i As Integer
    Dim NoExcanges As Integer


    'Exchange values in probs in descending order

    Do
        NoExchanges = True
        ' Loop through each element
        For i = 0 To UBound(Probs) - 1

            'If element is greater than the last exchange, else do nothing

            If Probs(i) > Probs(i + 1) Then
                NoExchanges = False
                ' Exchange probability values
                Temp = Probs(i)
                Probs(i) = Probs(i + 1)
                Probs(i + 1) = Temp
                ' Exchange residual probability values
                Temp = ResidualProbs(i)
                ResidualProbs(i) = ResidualProbs(i + 1)
                ResidualProbs(i + 1) = Temp
                ' Exchange cost values
                Temp = Costs(i)
                Costs(i) = Costs(i + 1)
                Costs(i + 1) = Temp
            End If
        Next i
    Loop While Not (NoExchanges)

    Temp = 0
    For i = 1 To UBound(Probs)
        If i = 1 Then
            Temp = Temp + Probs(i) * Costs(i)
        Else
            Temp = Temp + Probs(i) * ResidualProbs(i - 1) * Costs(i)
        End If
    Next i

    SortAndEvaluate = Temp
End Function

Can anyone give me any feedback please?

Answer 1

Try something like

Option Explicit

Function SortAndEvaluate(ByRef Probs As Range, ByRef ResidualProbs As Range, ByRef Costs As Range)

    Dim NumberOfProbs As Long
    Dim NumberOfProbsRows As Long
    Dim NumberOfProbsColumns As Long
    Dim RangeAddressProbs As String

    ' Dim for ResidualProbs and Costs
    ' ...

    NumberOfProbs = Probs.Cells.Count
    NumberOfProbsRows = Probs.Rows.Count
    NumberOfProbsColumns = Probs.Columns.Count
    RangeAddressProbs = Probs.Address

    ' also for ResidualProbs and Costs
    ' ...

    ' Might want some validation, e.g.
    If NumberOfProbsColumns <> 1 Then Exit Function
    If NumberOfResidualProbsColumns <> 1 Then Exit Function

    ' Get Values from range as an array
    Dim ValuesProbs As Variant
    Dim ValuesResidualProbs As Variant
    Dim ValuesCosts As Variant

    ValuesProbs = Probs
    ValuesResidualProbs = ResidualProbs
    ValuesCosts = Costs

    ' Do your logic stuff using the Values... arrays
    ' ...

    ' This example return value shows how to reference the Values... arrays (note you need to index the column too)
    SortAndEvaluate = ValuesProbs(NumberOfProbsRows, 1)

End Function