my questions is about the relationship between polynomial modeling and transfer function.
As well known, the transfer function h(t) for LTI system has the relationship between input x(t) and output y(t):
y(t) = x(t) * h(t) ----- eq(1)
where * is convolution operation.
Then, a system is modeled using a polynomial series as
y(t) = Σ a(i) [x(t)]^i ----- eq(2)
where i is an index for the polynomial series, and a(i) is the polynomial coefficient.
Here is a question.
The polynomial model itself " Σ a(i) [x(t)]^i " in eq(2) corresponds to
" x(t) * h(t) " in eq(1)
OR
" h(t) " in eq(1)?
I'm asking because a polynomial model which represents a certain system is considered as "transfer function" of the system in some articles.