Excel VBA code (technical index for trading system)

Sub EMA()
'''-----http://www.samurai-logic.com/
'''-----Project of Trading System Development
'''------------------------------------------------------------------
''----Ｂ列（日付）、Ｃ列（始値）、Ｄ列（高値）、Ｅ列（安値）、Ｆ列（終値）
''----
''----TextBox1に期間、TextBox2にずらす日数、
''--------------------------------------------------------------------

Dim length1%, length2%, length3%, LastRow&, i&

 Application.ScreenUpdating = False

 Worksheets("EMA").Activate
 LastRow = (Range("B4").End(xlDown).Row)
    
 Range("H5:H5000").ClearContents
    
 length1 = CInt(ActiveSheet.TextBox1.Value)  'period of moving average
 length2 = CInt(ActiveSheet.TextBox2.Value)  'Move Forword
      
 Range("H3") = "EMA(" & length1 & ":" & length2 & ")"
     
 For i = length1 + 4 To LastRow
    
  If i = length1 + 4 Then
      
    Cells(i + (length2), 8).Value = _
      WorksheetFunction.Average(Range("F" & i - (length1) + 1, "F" & i))
               
  Else
      
    Cells(i + (length2), 8).Value = Cells(i + (length2) - 1, 8).Value + _
     ((Cells(i, 6).Value - Cells(i + (length2) - 1, 8)) * 2 / (1 + length1))
         
      End If

    Next

    Range("H5", "H" & LastRow + (length2)).NumberFormatLocal = "0"
End Sub