Editing Signal (section)

==Signals and systems==
In [[electrical engineering]] (EE) programs, signals are covered in a class and field of study known as ''signals and systems''. Depending on the school, undergraduate EE students generally take the class as juniors or seniors, normally depending on the number and level of previous [[linear algebra]] and [[differential equation]] classes they have taken.<ref name="McMahon s and s">{{cite book|isbn=978-0-07-147578-5|url=https://www.amazon.com/gp/product/0071475788?selectObb=new|title=Signals & Systems Demystified|author=David McMahon|location=New York|publisher=McGraw Hill|year=2007|access-date=2017-09-11|archive-date=2020-01-22|archive-url=https://web.archive.org/web/20200122152613/https://www.amazon.com/gp/product/0071475788?selectObb=new|url-status=live}}</ref>

The field studies input and output signals, and the mathematical representations between them known as systems, in four domains: time, frequency, ''s'' and ''z''. Since signals and systems are both studied in these four domains, there are 8 major divisions of study. As an example, when working with continuous-time signals (''t''), one might transform from the time domain to a frequency or ''s'' domain; or from discrete time (''n'') to frequency or ''z'' domains. Systems also can be transformed between these domains like signals, with continuous to ''s'' and discrete to ''z''.

Signals and systems is a subset of the field of [[mathematical model]]ing. It involves circuit analysis and design via mathematical modeling and some numerical methods, and was updated several decades ago with [[dynamical system]]s tools including differential equations, and recently, [[Lagrangian mechanics|Lagrangians]]. Students are expected to understand the modeling tools as well as the mathematics, physics, circuit analysis, and transformations between the 8 domains.

Because mechanical engineering (ME) topics like friction, dampening etc. have very close analogies in signal science (inductance, resistance, voltage, etc.), many of the tools originally used in ME transformations (Laplace and Fourier transforms, Lagrangians, sampling theory, probability, difference equations, etc.) have now been applied to signals, circuits, systems and their components, analysis and design in EE. Dynamical systems that involve noise, filtering and other random or chaotic attractors and repellers have now placed stochastic sciences and statistics between the more deterministic discrete and continuous functions in the field. (Deterministic as used here means signals that are completely determined as functions of time).

EE taxonomists are still not decided where signals and systems falls within the whole field of signal processing vs. circuit analysis and mathematical modeling, but the common link of the topics that are covered in the course of study has brightened boundaries with dozens of books, journals, etc. called "Signals and Systems", and used as text and test prep for the EE, as well as, recently, computer engineering exams.<ref name="Signals and systems">{{cite book |isbn= 978-0073380681 |title= Signals and Systems: Analysis Using Transform Methods & MATLAB|author= M.J. Roberts |location=New York|publisher=McGraw Hill|year=2011}}</ref>