recursion

recursion (rɪˈkɜːʃən)
—n
1.	the act or process of returning or running back
2.	logic, maths the application of a function to its own values to generate an infinite sequence of values. The recursion formula or clause of a definition specifies the progression from one term to the next, as given the base clause f(0) = 0, f(n + 1) = f(n) + 3 specifies the successive terms of the sequence f(n) = 3n
[C17: from Latin recursio, from recurrererecur]
re'cursive
—adj

recursion definition

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.
See also recursion, recursive definition, tail recursion.
[Jargon File]
(1996-05-11)