Induction step:
Assume
is summable for (k-1) case .we proceed to prove it
for k case.
A neccesary
and sufficient conditon for a continuos rational
system to be a Causal and Stable
is that all the poles must lie in the left half
plane, i.e.
Re (s)< 0.
THEOREM :
A neccesary
and sufficient conditon for a discrete rational
system to be a Causal and Stable
is that all the poles must lie inside the unit circle,
i.e.|z|
< 1 .