Const k2 = 2 / 3
 
Function dot_match(ByVal x0 As Double, ByVal y0 As Double) As Boolean
   Dim r As Integer
   Dim КоличествоПересечений As Byte
    
   r = 3
   Do
      If Cells(r + 1, 2) = "" Then Exit Do
      If Пересекает(Cells(r, 2), Cells(r, 3), _
                       Cells(r + 1, 2), Cells(r + 1, 3), x0, y0) Then
         КоличествоПересечений = КоличествоПересечений + 1
      End If
      r = r + 1
   Loop
   If КоличествоПересечений Mod 2 = 0 Then
      dot_match = False
   Else
      dot_match = True
   End If
End Function
 
Private Function Пересекает(x1 As Double, y1 As Double, _
                    x2 As Double, y2 As Double, x0 As Double, y0 As Double) As Boolean
   Dim x_min As Double, x_max As Double
   Dim k1 As Double, b1 As Double, b2 As Double, x_ As Double
    
   Пересекает = False
    
   If x1 = x2 Then x2 = x1 + 0.001 'для вертикальных отрезков!
    
   If x1 > x2 Then
      x_max = x1
      x_min = x2
   Else
      x_max = x2
      x_min = x1
   End If
    
   k1 = (y2 - y1) / (x2 - x1)
   b1 = y1 - k1 * x1
    
   b2 = y0 - k2 * x0
    
   x_ = -(b2 - b1) / (k2 - k1)
    
   If (x_ > x_min And x_ <= x_max) And (x_ > x0) Then Пересекает = True 'And (x_ > x0) при k=1
End Function