Double-centers the matrix so that each rows and each columns sums to zero,
by subtracting the row mean in each row, subtracting the column mean in
each column, and adding the overall mean for each entry.
From a rectangular k x n matrix of dissimilarities, a square k x k
dissimilarity matrix is computed which contains just the dissimilarities
among the k objects described by the k rows.
Given a set of dissimilarity rows, a subsample of rows is constructed which
should be as representative as possible, using a greedy farthest-minimal
dissimilarity approach.
Computes inner product of two vectors of the same length,
the sum of entry-wise products x[0]*y[0]+...+x[n-1]*y[n-1],
where n is the minimum length of the vectors