“…The very idea of iterations with truncation has been already advocated in several papers, chiefly for Toeplitz-like matrices [8,9,[31][32][33], rank-structured matrices [4,5,12,13,21,27,32] (see also [22][23][24][25][26]) and wavelet-based sparsification [1,6,12,13]. However, the proofs provided so far only for some particular cases of structures have appeared as different individual proofs.…”