Stability radii of positive discrete-time systems under affine parameter perturbations

In this paper we study stability radii of positive linear discrete-time systems under affine parameter perturbations. It is shown that real and complex stability radii of positive systems coincide for arbitrary perturbation structures, in particular, for blockdiagonal disturbances as considered in mu-analysis. Estimates and computable formulae are derived for these stability radii. The results are derived for arbitrary perturbation norms induced by monotonic vector norms (e.g. p-norms, 1 less than or equal to p less than or equal to infinity). (C) 1998 John Wiley & Sons, Ltd.