说明：  对三维向量进行DTW相似度计算,可以很容易地扩展到更高的维数
(* This library includes the dynamic programming solution for vectored input signals represented * by the class Point. Currently, it has 3 dimensions- x, y, z. More can easily be added to this class. * No change would be required to the DTW class. Only keep in mind that the distance code has to be updated * to accomodate more dimensions.)