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12th July 2004

MC13: Permute a sparse matrix to block triangular form

Given the pattern of nonzeros of a sparse matrix \(\mathbf{A}\), finds a symmetric permutation that makes the matrix block lower triangular, i.e. finds \(\mathbf{P}\) such that \(\mathbf{L} = \mathbf{PAP} ^{-1}\) is block lower triangular.