Cybernetics Forrester at MIT in the 1950s, is a related field. Cybernetics has been defined in a variety of ways, by a variety of people, from a variety of disciplines. Cybernetician Stuart Umpleby reports some notable definitions: Other notable definitions include: The term "cybernetics" stems from κυβερνήτης ("cybernḗtēs") "steersman, governor, pilot, or rudder". As with the ancient Greek pilot, independence of thought is important in cybernetics. French physicist and mathematician André-Marie Ampère first coined the word "cybernetique" in his 1834 essay "Essai sur la philosophie des sciences" to describe the science of civil government. The term was borrowed by Norbert Wiener,
Wiener algebra functions on the unit circle. On the other hand an integration by parts, together with the Cauchy–Schwarz inequality and Parseval's formula, shows that More generally, for formula_8 (see ). proved that if has absolutely convergent Fourier series and is never zero, then its inverse also has an absolutely convergent Fourier series. Many other proofs have appeared since then, including an elementary one by . which is equivalent to Wiener's theorem. Wiener algebra In mathematics, the Wiener algebra, named after Norbert Wiener and usually denoted by , is the space of absolutely convergent Fourier series. Here denotes the circle group. The