An N-periodic discrete-time system in z-domain given by an N-periodic colle
ction of rational matrices is considered. Doubly coprime decomposition of t
hese matrices is studied. For such decompositions, the block-ordered concep
t is used. Further, the eight matrices in the generalized Bezout identity,
so that all of them are block-ordered, can be chosen. A relation among thes
e matrices at consecutive times is established. (C) 1999 Elsevier Science L
td. All rights reserved.