Analog computer
A form of computer using electronic or mechanical phenomena to model the problem being solved by using one kind of physical quantity to represent another.
Used in distinction to digital computers, in which physical or mechanical phenomena are used to construct a finite-state machine which is then used to model the problem being solved.
Analog computers operate on real numbers and are differential, whereas digital computers are limited to rational numbers and are algebriac. This means that analog computers have a larger potential computing domain than do digital computers. (see Godel's Theorom of Incompleteness) This enables analog computers to solve problems that are inextricable on digital computers.
Also see signals, set theory, computability theory, differential equation, dynamical systems, chaos theory.
An example:
- the abacus is a hand-operated digital computer
- the slide rule is a hand-operated analog computer
Examples of analog computers:
- Tide predictors
- Mechanical integrators
- Target predictors
- Hydraulic model of UK economy
- and (trivially) the slide rule