Empirically modified block incomplete factorizations
Dynamic variants of modified block incomplete factorization with modulated additive perturbations have been introduced recently and found to be superior to the standard block methods, in particular when applied to difficult problems for which the usual modified version gives rise to strongly isolated largest eigenvalues. We show here that in the case where the PDE coefficients are strongly anisotropic, care should be taken to provide some enough selection of the perturbed nodes in order to avoid a severe loss of efficiency.
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