Recursive filter with repeated poles

1. What are repeated poles?
2. What do you mean by recursive filter?
3. What is the difference between recursive and non recursive filters?

What are repeated poles?

Repeated poles simply means there are more than one pole at the same location. If a pole is not repeated then it is a Distinct Pole. Consider the simple case of a cascade of two integrators (in s) which is similar to the cascade of two accumulators (in z).

What do you mean by recursive filter?

In signal processing, a recursive filter is a type of filter which re-uses one or more of its outputs as an input.

What is the difference between recursive and non recursive filters?

In mathematics, a nonrecursive filter only uses input values like x[n − 1], unlike recursive filter where it uses previous output values like y[n − 1].