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–Khinchin theorem errors can show up as a divergence when the sequence length is modified. Some authors refer to formula_23 as the autocovariance function. They then proceed to normalise it, by dividing by formula_24, to obtain what they refer to as the autocorrelation function. Wiener–Khinchin theorem In applied mathematics, the Wiener–Khinchin theorem, also known as the Wiener–Khintchine theorem and sometimes as the Wiener–Khinchin–Einstein theorem or the Khinchin–Kolmogorov theorem, states that the autocorrelation function of a wide-sense-stationary random process has a spectral decomposition given by the power spectrum of that process. Norbert Wiener proved this theorem for the case of a deterministic function