Nested-Dissection Orderings for Sparse LU with Partial Pivoting

We describe the implementation and performance of a novel fill-minimization ordering technique for sparse LU factorization with partial pivoting. The technique was proposed by Gilbert and Schreiber in 1980 but never implemented and tested. Like other techniques for ordering sparse matrices for LU with partial pivoting, our new method preorders the columns of the matrix (the row permutation is chosen by the pivoting sequence during the numerical factorization). Also like other methods, the column permutation Q that we select is a permutation that minimizes the fill in the Cholesky factor of QT AT AQ. Unlike existing column-ordering techniques, which all rely on minimum-degree heuristics, our new method is based on a nested-dissection ordering of AT A. Our algorithm, however, never computes a representation of AT A, which can be expensive. We only work with a representation of A itself. Our experiments demonstrate that the method is efficient and that it can reduce fill significanly rela...

• Type: Conference
• Year: 2000
• Where: NAA
• Authors: Igor Brainman, Sivan Toledo
• Keywords: Fill-minimization Ordering Technique, Mathematics, NAA 2000, Partial Pivoting, Sparse LU Factorization