Recursion

You’ve seen functions that call other functions.

If a function calls itself, we call that recursion

Like with other functions, a call within a call establishes a call stack

With recursion, if you are not careful, this stack can get very deep.

Python has a maximum limit to how much it can recurse. This is intended to save your machine from running out of RAM.

Recursion is especially useful for a particular set of problems.

For example, take the case of the factorial function.

In mathematics, the factorial of an integer is the result of multiplying that integer by every integer smaller than it down to 1.

5! == 5 * 4 * 3 * 2 * 1

We can use a recursive function nicely to model this mathematical function