This paper introduces a simple way to evaluate the preconditioning effect in the shifted ICCG method. The proposed evaluation index is easily calculated with little additional memory in an incomplete factorization process; thus, it can be used for setting appropriate parameters for the solver, such as an acceleration factor and the ordering of unknowns, prior to the time-consuming iteration process. Numerical results show that the evaluation index gives the good estimate of the number of iterations necessary for convergence.

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The Algebraic multigrid (AMG) method is an efficient preconditioner for large-scale finite element analyses. However, in edge-element analyses, the large null space of the coefficient matrices causes difficulties in applying the AMG techniques. We present a new algebraic multigrid preconditioning for edge-element analyses. Numerical results show the advantage of the proposed preconditioner.