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R. B. Pachori and V. Gupta
Example of a dynamic system is as follows:
y(t) = 3x(t) + x (t − 3)
(12.17)
12.3.2.5 Causal and Noncausal Systems
For causal system, the output depends on the present and past values of the input
signal. On the other hand, the noncausal system output also depends on the future
values of the input signal.
Example of causal system is as follows:
y(t) = x(t) + x (t − 2)
(12.18)
The following is the example of a noncausal system:
y(t) = x (t + 2)
(12.19)
12.3.2.6 Invertible and Non-invertible Systems
A system can be considered as an invertible system if the input signal can be
obtained on the output signal of the system. When input signal cannot be obtained
on the output of the system, then a system is known as non-invertible system.
Example of an invertible system is as follows:
y(t) = 3x(t)
(12.20)
Example for a non-invertible system is as follows:
y(t) = 0
(12.21)
12.3.2.7 Stable and Unstable Systems
In stable system, bounded input signal provides bounded output signal, whereas in
unstable system, we will get unbounded output signal for the bounded input signal.
Example of stable system is given as follows:
y(t) = x(t)
(12.22)
Example of unstable system is as follows:
y(t) =
x(t)dt
(12.23)