
Changing the target functions requires re-computing steps 4 through
6. In this variant of the algorithm the k acts as the regularization
parameter; increasing k requires additional steps of the LSQR
algorithm to be computed in step 4. If k is decreased no extra
Lanczos iterates are needed, provided the iteration vectors
are saved. In any case steps 5 through 6 need to be
re-computed.