“…Large-scale linear discrete ill-posed problems with constraints arise in many applications and several different approaches to their solution have been proposed; see, e.g., Bardsley [13], Bertero and Boccacci [14, Section 6.3], Calvetti et al [15], Hanke et al [16], Kim [17], Morigi et al [18], Nagy and Strakoš [19], and references therein, in addition to the references already mentioned. There is presently not one best solution method for all constrained large-scale ill-posed problems.…”