I am stydying control systems, and I am trying to understand better the topic of causality.
I know that a system is causal if the actual state depends only on the past states and on the present state, so I can represent a causal system for example as:
And also I could represent a transfer function of a causal system as for example:
which has as step response:
which is not related to the previous example in state space, but I wrote this just as an example.
Now, I would like to understand better the behavior of a non-causal system. As far as I know, a non-causal system is not realizable, since it is a system in which the actual state depends on the future states, and this is impossible.
But I can't understand well this concept of non causality. For example what is an example of transfer function of a non causal system and its step response or frequency response?