I would like to indicate the progress of my quicksort. I understand that, per
iteration, progress can be calculated by using something like this:

myRange = iUpper - iLower + 1
Progress = Round((myRange * Log(myRange))/3) + (myRange/3)

...but I can't get any sensible values from it, I am sure I am missing
something major, and I confess my mathematical abilities are not up to the
task.

Can anyone help me to understand what I should be doing?

My quicksort takes a public 2 dimensional (x,y) array and sorts just on the
y part. The array is called FA, and varies in size, but here is how to call
my code assuming FA has 1000 records (0-999):

Call QuickSortFA(0, 999)

Here is my quicksort code:

Public Sub QuickSortFA(Optional iLower As Integer, Optional iUpper As Integer)
Dim iLowerValue As Integer
Dim iUpperValue As Integer
Dim vTest As String
Dim iMidValue As Integer
Dim vTemp As Variant
If iLower < iUpper Then
   iMidValue = Int((iLower + iUpper) / 2)
   vTest = LCase(FA(1, iMidValue))
   iLowerValue = iLower
   iUpperValue = iUpper
   Do
       Do While LCase(FA(1, iLowerValue)) < vTest
           iLowerValue = iLowerValue + 1
       Loop
       Do While LCase(FA(1, iUpperValue)) > vTest
           iUpperValue = iUpperValue - 1
       Loop
       If iLowerValue <= iUpperValue Then
           vTemp = FA(0, iUpperValue)
           FA(0, iUpperValue) = FA(0, iLowerValue)
           FA(0, iLowerValue) = vTemp
           vTemp = FA(1, iUpperValue)
           FA(1, iUpperValue) = FA(1, iLowerValue)
           FA(1, iLowerValue) = vTemp
           iLowerValue = iLowerValue + 1
           iUpperValue = iUpperValue - 1
       End If
   Loop Until iLowerValue > iUpperValue    
   If iUpperValue <= iMidValue Then
       Call QuickSortFA(iLower, iUpperValue)
       Call QuickSortFA(iLowerValue, iUpper)
   Else
       Call QuickSortFA(iLowerValue, iUpper)
       Call QuickSortFA(iLower, iUpperValue)
   End If
End If
End Sub