## Factorial Approximations

31/03/2020

$n!$ (and its logarithm) keep showing up in the analysis of algorithm. Unfortunately, it’s very often unwieldy, and we use approximations of $n!$ (or $\log n!$) to simplify things. Let’s examine a few!

## Stirling’s series

02/12/2014

Last week, we had a look at how g++ handles tail-recursion. Turns out it does a great job. One of the example used for testing the compiler was the factorial function, $n!$.

We haven’t pointed it out, but the factorial function in last week’s example computed the factorial modulo the machine-size (unsigned) integer. But what if we want to have the best possible estimation?