To visualize the execution of a recursive function, it is helpful to diagram the call stack of currently-executing functions as the computation proceeds. Which leads to two different implementations: Iterativeįor ( int i = 1 i 0, where we compute the result with the help of a recursive call to obtain (n-1)!, then complete the computation by multiplying by n. We can define factorial in two different ways: In a recursive step, we compute the result with the help of one or more recursive calls to this same function, but with the inputs somehow reduced in size or complexity, closer to a base case.Ĭonsider writing a function to compute factorial.

Otherwise, we can represent pow(x, n) as x pow(x, n - 1).In maths, one would write x n x x n-1. In a base case, we compute the result immediately given the inputs to the function call. If n 1, then everything is trivial.It is called the base of recursion, because it immediately produces the obvious result: pow(x, 1) equals x.Comfort with recursive implementations will be necessary for upcoming classes.Ī recursive function is defined in terms of base cases and recursive steps. Today’s class will delve more deeply into recursion than you may have gone before. Since you’ve taken 6.01, recursion is not completely new to you, and you have seen and written recursive functions like factorial and fibonacci before.

We want you to be comfortable and competent with recursion, because you will encounter it over and over.

Recursion is not appropriate for every problem, but it’s an important tool in your software development toolbox, and one that many people scratch their heads over. We’ll focus on one particular technique, recursion. In today’s class, we’re going to talk about how to implement a method, once you already have a specification.

You dont know js recursion