Excel VBA code (technical index for trading system)

Sub Kairi()

'''-----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１、TextBox2に期間２
''--------------------------------------------------------------------
Dim length1%, length2%, LastRow&, i&, j%, j2&

Application.ScreenUpdating = False
 
Worksheets("かい離率").Activate

LastRow = Range("B4").End(xlDown).Row

length1 = CInt(ActiveSheet.TextBox1.Value)
length2 = CInt(ActiveSheet.TextBox2.Value)

Range("H3") = "かい離率:" & length1
Range("I3") = "かい離率:" & length2

Range("H5:I5000").ClearContents

For i = length1 + 5 To LastRow

   Cells(i, 8).Value = _
   (Cells(i, 6).Value - WorksheetFunction.Average(Range("F" & i, _
   "F" & i - (length1) + 1))) * 100 / _
   WorksheetFunction.Average(Range("F" & i, "F" & i - (length1) + 1))
   
 If i > (length2) + 5 Then
   Cells(i, 9).Value = _
   (Cells(i, 6).Value - WorksheetFunction.Average(Range("F" & i, _
   "F" & i - (length2) + 1))) * 100 / _
   WorksheetFunction.Average(Range("F" & i, "F" & i - (length2) + 1))
   
 End If

Next i
 
Range("H5", "I" & LastRow).NumberFormatLocal = "0.00"
Application.ScreenUpdating = True
End Sub