x=a*cos(t)
    y=b*sin(t)

Public Function PointOnEllipse(X As Double, y As Double) As Boolean
    Dim dW As Double
    dW = Acos(X / StreckungsFaktorA)
    PointOnEllipse = Replace(y, ",", ".") = Replace(StreckungsFaktorB * Sin( _
      dW), ",", ".")
End Function
 
Function Acos(ByVal X As Double) As Double
    Acos = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1)
End Function