1 Introduction
Positive systems whose states and outputs always remain nonnegative whenever both initial conditions and inputs take nonnegative values can be easily encountered in real world, for instance, power system chemical engineering, networks of reservoirs [1] and population dynamics [2], and so forth. However, the positive constraint of systems may give rise to invalidation of some existing results on general systems. Accordingly, positive systems have captured widespread attention of researchers in control community over the past few years. Meanwhile, some achievements for positive systems in theory and applications have been proposed [1, 3–5].