Excel VBA Ctrl-Shift-Enter 数组 function 与编写长工作表相比非常慢

Question

I have written a function NA_2_X(Range, Variant) to accept an array, convert all #NA to a Variant, and return the new array:

{=NA_2_X(A1:A3000, 0)}

This is giving much slower execution than writing a laborious worksheet function:

{=IF(ISNA(A1:A3000), 0, A1:A3000)}

300 calls to NA_2_X() takes about 10s, whereas the IF() statement is almost instant. Ultimately I want to do something more complicated and can't use an if() statement.

Function NA_2_X(ByVal rng As Range, ByVal X As Variant) As Variant
    Dim NoRows As Long, NoCols As Long
    Dim r As Long, c As Long
    Dim ret() As Variant

    NoRows = rng.Rows.Count
    NoCols = rng.Columns.Count

    ReDim ret(1 To NoRows, 1 To NoCols)

    For c = 1 To NoCols
        For r = 1 To NoRows
            If Application.IsNA(rng(r, c)) Then
                ret(r, c) = X
            Else
                ret(r, c) = rng(r, c)
            End If
        Next r
    Next c

    NA_2_X = ret
    Exit Function
End Function

The loop itself seems pretty quick, it is just the few lines in the heart of the loop that seem so slow. If I remove the call to IsNA() it takes about half the time, but is still slow.

Answer 1

In addition to BigBen's suggestion, replacing "Application.IsNA(rng(r,c))" with "IsError(tmp(r,c))" has made the routine nice and fast.