LQ, triangular-pentagonal Node1 LQ, triangular-pentagonal Node3 tplqt:          QR factor Node1->Node3 Node4 tplqt2:         QR factor, level 2 Node1->Node4 Node5 tpmlqt:         applies Q Node1->Node5 Node2 Orthogonal/unitary factors (QR, CS, etc.) Node2->Node1 .