If I understand correctly z transform analysis can't work as these systems are fundamentally non linear. In fact, the "non linear" part, i.e. the activation fun

If I understand correctly z transform analysis can't work as these systems are fundamentally non linear. In fact, the "non linear" part, i.e. the activation functions, are the part of these networks that allow for them to be universal function approximators and learn arbitrary things, versus just becoming a simple linear system.