Blum–Shub–Smale machine
In computation theory, the Blum–Shub–Smale machine, or BSS machine, is a model of computation introduced by Lenore Blum, Michael Shub and Stephen Smale, intended to describe computations over the real numbers. Essentially, a BSS machine is a random-access machine with registers that can store arbitrary real numbers and that can compute rational functions over reals in a single time step.