Editing Norbert Wiener (section)

=== Nonlinear control theory ===
Wiener studied [[polynomial chaos]], a key piece of which is the Hermite-Laguerre expansion. This was developed in detail in ''Nonlinear Problems in Random Theory''.

Wiener applied Hermite-Laguerre expansion to nonlinear system identification and control. Specifically, a nonlinear system can be identified by inputting a white noise process and computing the Hermite-Laguerre expansion of its output. The identified system can then be controlled.<ref>{{cite journal |last=Brick |first=Donald B. |date=March 1968 |title=On the applicability of Wiener's canonical expansions |journal=IEEE Transactions on Systems Science and Cybernetics |volume=4 |issue=1 |pages=29–38 |doi=10.1109/TSSC.1968.300185 |issn=0536-1567 |url=https://ieeexplore.ieee.org/document/4082114 }}</ref><ref>{{Cite journal |last1=Harris |first1=G.H. |last2=Lapidus |first2=Leon |date=1967-06-01 |title=Identification of Nonlinear Systems |journal=Industrial & Engineering Chemistry |language=en |volume=59 |issue=6 |pages=66–81 |doi=10.1021/ie50690a012 |issn=0019-7866 |url=https://pubs.acs.org/doi/abs/10.1021/ie50690a012 }}</ref>
[[File:Norbert Wiener.webp|thumb|Norbert Wiener in [[Massachusetts Institute of Technology|MIT]], 1963]]