Построение графика

Sub Grapher()
Dim a As Double
Dim b As Double
Dim n As Integer
Dim dx As Double
Dim Form As String
Dim i  As Integer
Dim x As Double
Dim adr As String
Dim RR() As String
Dim FF As String
Dim j As Integer
 
    n = 200
    
    a = Range("L2").Value
    b = Range("N2").Value
    dx = (b - a) / n
    
    Form = Range("B2").Value
    
    RR = Parse(Form)
        
    For i = 1 To n
    
        x = a + (i - 1) * dx
    
        adr = "AA" + CStr(i)
    
        Range(adr).Value = x
    
        FF = ""
        For j = 1 To UBound(RR)
            If RR(j) = "x" Then
               FF = FF + adr
            Else
               FF = FF + RR(j)
            End If
        Next j
    
        Range("AC1").Formula = "=" & FF
 
        Range("AB" + CStr(i)).Value = Range("AC1").Value
        
    Next i
 
End Sub
 
Function Parse(F As String) As String()
Dim Res() As String
Dim Tmp As String
Dim i As Integer
Dim j As Integer
Dim s As String
 
    ReDim Res(1 To 1000) As String
    
    i = 0
    
    For j = 1 To Len(F)
        s = Mid(F, j, 1)
        Select Case (s)
               Case "+", "-", "*", "/", "^", "(", ")"
                    If Len(Tmp) > 0 Then
                       i = i + 1
                       Res(i) = Tmp
                    End If
                    i = i + 1
                    Res(i) = s
                    Tmp = ""
                Case Else
                    Tmp = Tmp + s
        End Select
    Next j
    
    If Len(Tmp) > 0 Then
       i = i + 1
       Res(i) = Tmp
    End If
    
    ReDim Preserve Res(1 To i) As String
    
    Parse = Res
 
End Function