In Simulink, I defined a Discrete State Space model. However it only has a an input port for u and another for y, but I need to track the state x. How can I do it without building a state observer (which in this case should not be needed since the input is generated from Simulink itself with step blocks)? Note that I cannot modify C to be eye(n) and D to be zeros(n,m), because the discrete system I'm working with comes from the minimal representation of an identified transfer function, so I cannot just modify the matrices because that would modify the underlying process too.