BLOCK_DIAGONALIZE - reorders a matrix heuristically using a 
  clustering result
    [A, N_ROWS, N_COLS, ROW_INDS, COL_INDS]=BLOCK_DIAGONALIZE(A, 
    CLUSTERS) reorders matrix A using the clustering result 
    represented by the structure CLUSTERS. N_ROWS and N_COLS 
    store the last row and column index for each row and column 
    block resprectively, while ROW_INDS and COL_INDS contain the 
    permuted row and column indices.
 
  Copyright 2011 Dimitrios Zeimpekis, Eugenia Maria Kontopoulou, 
                 Efstratios Gallopoulos