Private Function ValueOf(ByVal str As String) As Double
    If String.IsNullOrEmpty(str) Then Return 0.0
    Dim l As Integer = str.Length + 1
    Dim ok As Boolean, vl As Double
    While l > 0 And Not ok
        l -= 1
        ok = Double.TryParse(str.Substring(0, l), vl)
    End While
    Return vl
End Function