I = [ 1     1     1     1     2     3     6     6
         1     1     2     1     4     5     6     8
         1     1     1     1    10    15     7     7
         1     1     1     1    20    25     7     7
        20    22    20    22     1     2     3     4
        20    22    22    20     5     6     7     8
        20    22    20    20     9    10    11    12
        22    22    20    20    13    14    15    16];
S = qtdecomp(I,5);
full(S)