Optimal 2-cyclic MSOR for ``bowtie'' spectra and the ``continuous'' Manteuffel algorithm (Q1369343)

Let a linear system be given with a matrix which is in a block partitioned form, has nonsingular diagonal blocks, and is block 2-cyclic consistently ordered. For such problems a stationary successive overrelaxation method (MSOR) is given, to solve its cyclically reduced linear system by a two-step iterative method. The method is asymptotically faster than any of other known methods for the same problem and can also cover a wider class of matrices.