Parallel frequency filtering

The frequency filtering method is a robust and efficient ILU-like solver for large sparse systems (cf. [9,10]). Combining this method with the so-called Schur-complement DD method, we obtain a fast parallel solver. In this context, frequency filtering can be applied as solver inside the subdomains as well as for the treatment of the arising Schur complements. Especially for those, the method is well suited since it is highly parallelizable by recursively applying the same decomposition as to the original system. In this paper, an implementation of the frequency filtering domain decomposition (FFDD) method on a multiprocessor system will be presented and the numerical results of some variants thereof be discussed. The scaling behaviour of the algorithm for an increasing number of processors is almost optimal.