---
categories: Combinatorics
---

## Operations

### Multiplication
Multiplying two finite formal power series is the same as multiplying two polynomials. That can be done in $O(n\log n)$ time with [Fast Fourier transform]().

### Division
Calculating the multiplicative inverse of a formal power series can be done in $O(n\log n)$. [^1]

### Square root
Calculating the square root of a formal power series can be done in $O(n\log n)$. [^1]

## See also
- [Generating function]()

## External links
- [HOPS - Handy Operations on Power Series](http://akc.is/hops/)
- [Power serious: power series in ten one-liners](https://www.cs.dartmouth.edu/~doug/powser.html)


[^1]: <http://codeforces.com/blog/entry/12513>