# recursion

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## recursion

[ri′kər·zhən]
(computer science)
A technique in which an apparently circular process is used to perform an iterative process.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## recursion

(mathematics, programming)
When a function (or procedure) calls itself. Such a function is called "recursive". If the call is via one or more other functions then this group of functions are called "mutually recursive".

If a function will always call itself, however it is called, then it will never terminate. Usually however, it first performs some test on its arguments to check for a "base case" - a condition under which it can return a value without calling itself.

The canonical example of a recursive function is factorial:

factorial 0 = 1 factorial n = n * factorial (n-1)

Functional programming languages rely heavily on recursion, using it where a procedural language would use iteration.