New upper bounds for the solution of the discrete algebraic Lyapunov equati
on (DALE) P = APA(T) + Q are presented. The only restriction on their appli
cability is that A be stable; there are no restrictions on the singular val
ues of A nor on the diagonalizability of A. The new bounds relate the size
of P to the radius of stability of A. The upper bounds are computable when
the large dimension of A make direct solution of the DALE impossible. The n
ew bounds are shown to reflect the dependence of P on A better than previou
sly known upper bounds. (C) 1999 Elsevier Science Ltd. All rights reserved.