Cyberman choosing to fill in gaps in the history of the Cybermen or depict new encounters between them and the Doctor. The species also appeared in the "Doctor Who" TV spin-off "Torchwood", appearing in the fourth episode, "Cyberwoman" (2006). The name "Cyberman" comes from cybernetics, a term used in Norbert Wiener's book "Cybernetics or Control and Communication in the Animal and the Machine" (MIT Press, 1948). Wiener used the term in reference to the control of complex systems in the animal world and in mechanical networks, in particular self-regulating control systems. By 1960, doctors were performing research into surgically or mechanically
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