Category:Recursion

Recursion is the idea that a function can come to an answer by repeatedly "calling itself" with new arguments until a "base case" is met. One good example is a factorial function. The base case for factorial is "0!" (some people like to use 1 or 2, but for instructional purposes 0 is OK). When 5 is sent as an argument to a recursive factorial function, the function does no know the answer right away. All it knows is that 5! = 5 * 4!. so it calls itself to find out what 4! is. This process continues until it gets to 0!, which is 1. Now it has built up a train of answers: 5! = 5 * 4! = 5 * 4 * 3! etc. and it can find the answer.

A pseudocode-ish function to demonstrate recursion would look something like this:

function F with arguments
    if end condition is not met
      return F called with new set of arguments
    else
      return end condition value

Below is a list of examples of recursion in computing.