RQ Node4 gerq2:          RQ factor, level 2 Node1 RQ Node1->Node4 Node3 gerqf:          RQ factor Node1->Node3 Node8 {un,or}gr2:     step in ungrq Node1->Node8 Node5 {un,or}grq:     generate explicit Q from gerqf Node1->Node5 Node7 {un,or}mr2:     step in unmrq Node1->Node7 Node6 {un,or}mrq:     multiply by Q from gerqf Node1->Node6 Node2 Orthogonal/unitary factors (QR, CS, etc.) Node2->Node1 .