Abstract de la publi numéro 6602

We consider the LU factorization of unsymmetric sparse matrices using a three-phase approach (analysis, factorization and triangular solution). Usually the analysis phase first determines a set of potentially good pivots and then orders this set of pivots to decrease the fill-in in the factors.We present a family of ordering algorithms that can be used as apreprocessing step prior to performing sparse LU factorization. The ordering algorithms simultaneously achieve the objectives of selecting numerically good pivots and preserving the sparsity. We describe the algorithmic properties and difficulties in its implementation. By mixing the two objectives we show that we can reduce the amount of fill-in the factors and reduce the number of numerical problems during factorization.