formula for array max if Excel VBA - excel

Question

So this is my formula:
ws8.Range("Y2:Y" & lrowWFS).FormulaArray = "=Max(if(x2='New Stock Data'!H:H,'New Stock Data'!G:G))"
Problem is it's returning to {=Max(if(x2='New Stock Data'!H:H,'New Stock Data'!G:G))} in Y3 onwards.
Any idea how to solve?

Answer 1

It should be as simple as to change FormulaArray to Formula. (I haven't tested this), try:
ws8.Range("Y2:Y" & lrowWFS).Formula = "=Max(if(x2='New Stock Data'!H:H,'New Stock Data'!G:G))"

Answer 2

Couple of things. The generic formula looks like this: {=MAX(IF(criteria_range=criteria,value_range))}. So, instead of x2='New Stock Data'!H:H, you want to use: 'New Stock Data'!H:H=x2. Other than that, unlike regular formulas, array formulas assigned to a range do not adjust relative cell references.
E.g. Range("A1:A2").Formula = "=B1" will successively lead to =B1 and =B2, while Range("A1:A2").FormulaArray = "=B1" will lead to 2x =B1.
One solution is to loop through your range and assign the array formulas to each cell individually. E.g.
Dim rng As Range
Dim lrowWFS As Long
lrowWFS = 3
Set rng = ws8.Range("Y2:Y" & lrowWFS)
For Each cell In rng
cell.FormulaArray = "=MAX(IF('New Stock Data'!H:H=" & Cells(cell.Row, "X").Address(False, False) & ",'New Stock Data'!G:G))"
Next cell
A better solution would be to use SUMPRODUCT instead. This avoids the use of an array formula, and thus also the need for a loop.
E.g.:
With rng
.Formula = "=SUMPRODUCT(MAX(('New Stock Data'!H:H=X2)*('New Stock Data'!G:G)))"
End With
More in general, I would advise proper specification of the ranges in the formula. Define first_row and last_row and use something like this:
"=SUMPRODUCT(MAX(('New Stock Data'!H$" & first_row & ":H$" & last_row & "=X2)*('New Stock Data'!G$" & first_row & ":G$" & last_row & ")))"