  The article analyzes similarity of closed polygonal curves in Frechet metric,
which is stronger than the well-known Hausdorff metric and therefore is more
appropriate in some applications. An algorithm that determines whether the
Frechet distance between two closed polygonal curves with m and n vertices is
less than a given number is described. The described algorithm takes O(mn) time
whereas the previously known algorithms take O(mn log(mn)) time.
