“…There exist various generalizations of the Lanczos process, like block variants, e.g., [36,12,4], and variants with different numbers of left-hand and right-hand side starting vectors, e.g., [1]. Recently, Lanczos processes with s ∈ N left-hand side starting vectors and one right-hand side starting vector are enjoying a renaissance: in disguise, namely, as the workhorses of the IDR [39] and IDR(s) [34,10] based methods, see, e.g., [15,33,32].…”