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Computation is a general term for any type of information processing. This includes phenomena ranging from simple calculations to human thinking. In a more narrow meaning, computation is a process following a well defined model that is understood and can be expressed in an algorithm, protocol, network topology, etc.
Classes of computation Computation can be classified by at least three orthogonal criteria: digital vs analog, sequential vs parallel, batch vs interactive. In computer science, several formal models for digital computation were proposed. They have different expressive power to describe computation. Most common models describe computability of functions: finite state automaton, push-down automaton, Turing machine. In these models, input data is transformed into output data by a computer. In this case, computation proceeds in a series of state transitions computer performs on a given input. In practice, digital computation is often used to simulate natural processes (for example, Evolutionary computation), including those that are more naturally described by analog models of computation (for example, Artificial neural network). In this situation, it is important to distinguish between the mechanism of computation and the simulated model. Computations as a physical phenomenon A typical example of a physical computation is the evolution over time of a digital computer. Other examples of physical computations are derived from quantum computers, DNA computers, molecular computers or analog computers. Computations as a mathematical object In computer science (which is sometimes described as the discipline that studies computations) and in mathematical logic, mathematical models of computers are defined; a typical model is the Turing machine. In this context, a computation thus becomes a mathematical object: the evolution over time of a Turing machine. The sub-field of computer science which studies mathematical models of computations is called the theory of computation. History The word computation has an archaic meaning (from its Latin etymological roots), but the word has come back in use with the arising of a new scientific discipline: computer science. See also | ||||||||
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