  In this comment, we investigate a common used algorithm proposed by Newman
[M. E. J. Newman, Phys. Rev. E {\bf 64}, 016132(2001)] to calculate the
betweenness centrality for all vertices. The inaccurateness of Newman's
algorithm is pointed out and a corrected algorithm, also with O($MN$) time
complexity, is given. In addition, the comparison of calculating results for
these two algorithm aiming the protein interaction network of Yeast is shown.
