Sorry this is very simple but I do not know. Why the H-infinity methods that are used in control theory are said to work on Hardy space? If the question is not appropriate then how H-infinity methods are related to Hardy space? May I request few comments? Sorry if the question is not clear:It refers to the Wikipedia link:
http://en.wikipedia.org/wiki/Hardy_space
In the page it is written as:
Hardy spaces have a number of applications in mathematical analysis itself, as well as in control theory (such as H∞ methods) and in scattering theory.
So my question was what is the best way to understand how Hardy space is utilized by control theory. Hope it is clear now.