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