  A class of discrete-time nonlinear positive time-delay switched systems with
sector-type nonlinearities is studied. Sufficient conditions for the existence
of common and switched diagonal Lyapunov--Krasovskii functionals for this
system class are derived; these are expressed as feasibility conditions for
systems of linear algebraic inequalities. Corresponding spectral conditions for
the existence of common L--K functionals are also described. Furthermore, it is
shown that the proposed approaches can be applied to discrete-time models of
digital filters and neural networks. Finally, a numerical example is given to
illustrate the effectiveness of theoretical results.
