Correction: Random reordering in SOR-type methods

My joint paper (Numerische Mathematik 135:1207–1220, 2017. https://doi.org/10.1007/s00211-016-0829-7 ) with W. Zhou contains two errors which concern the derivation of some auxiliary norm estimates of the lower triangular projection for positive semi-definite Hermitean matrices in dependence on coordinate permutations. These errors are corrected. The main results of Oswald and Zhou (Numerische Mathematik 135:1207–1220, 2017. https://doi.org/10.1007/s00211-016-0829-7 ) about the convergence behavior of so-called shuffled and preshuffled SOR iterations are not affected.