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–Hopf method Wiener–Hopf method The Wiener–Hopf method is a mathematical technique widely used in applied mathematics. It was initially developed by Norbert Wiener and Eberhard Hopf as a method to solve systems of integral equations, but has found wider use in solving two-dimensional partial differential equations with mixed boundary conditions on the same boundary. In general, the method works by exploiting the complex-analytical properties of transformed functions. Typically, the standard Fourier transform is used, but examples exist using other transforms, such as the Mellin transform. In general, the governing equations and boundary conditions are transformed and these transforms are used to define