Exponential moving average using array in Excel VBA

[Super P]

The array VBA code below calculates 9 periods exponential moving average of the values in Column U (from row 31 to last row ~row 6983). The output will be in Column V (from row 39 to last row). he problem now the second output value is 39 rows below i.e. cell V78, this should be located in cell V40, appreciate any VBA expert help, thanks

Option Explicit

Sub EMA9()
   
    Dim valArray As Variant
    Dim runSum, EMA9() As Double
    Dim i, lastRow, lRow, firstRow, x1, x2, iPeriod, iCol As Long

    'Step1 - set last row and reference range to calculate
    With Worksheets("Sheet1")
      lastRow = .Cells(Rows.Count, 1).End(xlUp).Row
      valArray = .Range(.Cells(1, 21), .Cells(lastRow, 21)).Value2
    End With
   
    'Step2 - set lower and upper limit
    iPeriod = 9
    x1 = 2 / (iPeriod + 1)
    x2 = 1 - (2 / (iPeriod + 1))
    ReDim EMA9(LBound(valArray, 1) - 38 To UBound(valArray, 1), 1 To 1)
   
    'Step3 - calculate first row value, [sum (row 31 to row 39)]
    firstRow = 31
    runSum = 0
    For i = firstRow To (iPeriod + 30)
      runSum = runSum + valArray(i, 1)
    Next
   
    'Step4 - calculate first row average value, [average (row 31 to row 39)]
    EMA9(1, 1) = runSum / iPeriod
   
    'Step5 - calculate the 2nd row (row 32) value onwards, [current value of valArray * x1 + previous value of EMA9 * x2]
    For i = (iPeriod + firstRow) To UBound(valArray, 1)
        EMA9(i, 1) = valArray(i, 1) * x1 + EMA9(i - 1, 1) * x2
    Next
   
    'Step6 - write the values to worksheet
    iCol = 22
    With Worksheets("Sheet1")
        .Range(.Cells((iPeriod - 8), iCol), .Cells(lastRow, iCol)).Value2 = EMA9
    End With
   
    'Step7 - clear memory
    Erase valArray: Erase EMA9

End Sub

 

[BSALV]

in your 365, perhaps this one is easier to understand

    MyRows = WorksheetFunction.Sequence(6000 - 39 + 1, 1, 39)  '2D-array starting with 39 until 6000

you can also write immediately 5962 instead of that formula.