72. The apparatus of claim 71 wherein a feature vector is calculated as 
 ū i =u i S where u i is a row vector associated with an instance i, and S is the singular diagonal matrix.
72. The apparatus of claim 71 wherein a feature vector is calculated as 
 ū i =u i S where u i is a row vector associated with an instance i, and S is the singular diagonal matrix. 73. The apparatus of claim 72 wherein the distance between two feature vectors is determined by a metric comprising a similarity measure, C, between two feature vectors, ū i and ū j , wherein C is calculated as C ⁡ ( u _ i , u _ j ) = cos ⁡ ( u i ⁢ S , u j ⁢ S ) = u i ⁢ S 2 ⁢ u j T  u i ⁢ S  ⁢  u j ⁢ S  for any 1≦i, j≦M.