BISECTING_NNDSVD - a bisecting form of the the Non-Negative Double
  Singular Value Decomposition Method [2]. 
    BISECTING_NNDSVD applies a bisecting form of the the 
    Non-Negative Double Singular Value Decomposition Method [2] 
    using a PDDP-like [2] clustering Method. 
    [W, H]=BISECTING_NNDSVD(A, k, svd_method) returns a non-negative 
    rank-k approximation of the input matrix A using svd_method for 
    the SVD (possible values svds, propack).
 
    REFERENCES: 
    [1] D.Boley, Principal Direction Divisive Partitioning, Data 
    Mining and Knowledge Discovery 2 (1998), no. 4, 325-344.
    [2] C. Boutsidis and E. Gallopoulos. SVD-based initialization: 
    A head start on nonnegative matrix factorization.  Pattern 
    Recognition, Volume 41, Issue 4, Pages 1350-1362, April 2008.
 
  Copyright 2011 Dimitrios Zeimpekis, Eugenia Maria Kontopoulou, 
                 Efstratios Gallopoulos