Editing Signal processing (section)

===Nonlinear===
Nonlinear signal processing involves the analysis and processing of signals produced from [[nonlinear system]]s and can be in the time, [[frequency]], or spatiotemporal domains.<ref name="Billings">{{cite book |last=Billings |first=S. A. |title=Nonlinear System Identification: NARMAX Methods in the Time, Frequency, and Spatio-Temporal Domains |publisher=Wiley |year=2013 |isbn=978-1-119-94359-4 }}</ref><ref name="VSA">{{cite book |author=Slawinska, J. |author2=Ourmazd, A. |author3=Giannakis, D. |title=2018 IEEE Statistical Signal Processing Workshop (SSP) |chapter=A New Approach to Signal Processing of Spatiotemporal Data |pages=338–342 |publisher=IEEE Xplore |year=2018 |doi=10.1109/SSP.2018.8450704|isbn=978-1-5386-1571-3 |s2cid=52153144 }}</ref> Nonlinear systems can produce highly complex behaviors including [[bifurcation theory|bifurcations]], [[chaos theory|chaos]], [[harmonics]], and [[subharmonics]] which cannot be produced or analyzed using linear methods. 

Polynomial signal processing is a type of non-linear signal processing, where [[polynomial]] systems may be interpreted as conceptually straightforward extensions of linear systems to the nonlinear case.<ref>{{cite book |author1=V. John Mathews |author2=Giovanni L. Sicuranza |title=Polynomial Signal Processing |date=May 2000 |isbn=978-0-471-03414-8 |publisher=Wiley}}</ref>