Inside a loop, how to indicate "all rows" when taking the mean of multiple columns (Visual Basic) - vba

Question

I have a loop wherein I take the mean of several columns of numbers with the same number of rows each.
The point of the loop is to capture these means in a new vector.
So for each loop I need to indicate "all rows". In matlab this would be easy, just use ":" But I can't figure out what the analogy is in VB. Please help! Thanks.
(Please advise me as to what I put in the code below where I have ALLROWS).
My attempt so far:
For i = 1 To CA
mrCA11(i) = Application.WorksheetFunction.Average(revCA11(**ALLROWS**,i))
Next i
In matlab this would be:
For i = 1:CA
mrCA11(i) = mean(revCA11(:,i));
Next i
EDIT: I've also tried this trick to no avail:
For j = 1 To CA
For i = 1 To s11
temp11(i) = revCA11(i, j)
Next i
mrCA11(j) = Application.WorksheetFunction.Average(temp11)
Next j
I get the error message: "Unable to get the Average property of the Worksheet Function class"

Answer 1

As everybody (Tim and shahkalpesh at least) pointed out, we need to understand what is revCall or more specifically, we need to understand how you want to give them ALL ROWS in argument.
Finding the last row (or column or cell)
A common Excel issue is to find the last used row / column / cell.
This will give you the end of your vector.
Excel give you several methods to deal with this:
xlTypeLastCell
Last cell used in the entire sheet (regardless if it's used in column A or not)
lastRow = ActiveSheet.Cells.SpecialCells(xlCellTypeLastCell).Row
End(xlUp)
Last cell used (including blanks in-between) in Column A is as simple as this:
lastRow = Range("A" & Rows.Count).End(xlUp).Row
End(xlToLeft)
Last cell used (including blanks in-between) in Row 1 is as simple as this:
lastRow = ActiveSheet.Cells(1, Columns.Count).End(xlToLeft).Row
UsedRange
Last cell used in the WorkSheet (according to Excel interpretation):
Set rangeLastCell = ActiveSheet.UsedRange
Using an array as argument
The methods above told you how to find the last row (if this is what you need). You can then easily create your vector and use it in your procedure revCA11.
You can either give an array as argument as Tim pointed out in his answer with this kind of statement:
myArray = ActiveSheet.Range("A1", Cells(lastRow, lastColumn).Value
Or you can use the integer (or long) to build your vector inside your procedure as simple as declaring a range:
Range("A1:A" & lastRow)

Answer 2

You might clarify exactly how revCA11 is declared/created, but maybe something along these lines might work for you:
Sub Tester()
Dim arr, x
arr = ActiveSheet.Range("A1:D5").Value '2-D array
'average each column
Debug.Print "Columns:"
For x = 1 To UBound(arr, 2)
Debug.Print x, Application.Average(Application.Index(arr, 0, x))
Next x
'average each row
Debug.Print "Rows:"
For x = 1 To UBound(arr, 1)
Debug.Print x, Application.Average(Application.Index(arr, x, 0))
Next x
End Sub