I have the following function:

Option Explicit

Static Function abc(a, Optional b As Range)
a = a
If a = 0 Then
Dim m
m = Range("rr")
abc = 0
Else
abc = m(a, 1)
End If
End Function

In my sheet I have:
=abc(0,A1:A3)
=abc(1,A1:A3)
=abc(2,A1:A3)
=abc(3,A1:A3)

When I change a cell in A1:A3, why recalc does not start? I am forced
to use Ctrl-Alt-F9, which I don't like.

What's wrong with my code?

Vicente Soler