Non-volatile UDF always recalculating

Question

I am trying to make a non-volatile UDF but it seems not possible. So here is a my very simple test-UDF:

Option Explicit
Dim i As Integer

Sub Main()

i = 0
[A1]         


        

Answer 1

I found the solution, and it is indeed a very simple one but also made this hard to debug: If you make any change to your VBA code all the UDF get flagged for recalculation! I modified the degug code of David:

Sub main()

'nothing depends on the Value in [A13]
[A13] = "" 
[A13] = "hgdg"
[A13] = ""
i = 46

End Sub

Function f_appvol(rng As Range)

Application.Volatile
Debug.Print "f_appvol"

f_appvol = rng.Value
End Function

Function f_appNOTvol(rng As Range)
Application.Volatile (False)
Debug.Print "f_appNOTvol"

f_appNOTvol = rng.Value
End Function

Function f_omit(rng As Range)

Debug.Print "f_omit"
f_omit = rng.Value

End Function

After entering the code and running it for the first time, only f_appvol is recalculated. If you now change i=46 to i=47 and execute it, all the UDF get recalculated. All subsequent runs after that first run after the change give the expected behaviour.