# Expectation Symbol in LaTeX

After looking for a builtin expectation symbol in LaTeX, and coming up with none, I’ve defined one. Just add:

```% Expectation symbol \DeclareMathOperator*{\E}{\mathbb{E}}```

to your LaTeX preamble and you’re done. You’ll also need to add `\usepackage{amsmath}` or in LyX to tick “Use AMS math package” under Document->Settings->Math Options.

Using the starred version of `\DeclareMathOperator` makes sure subscripts goes beneath the symbol in display mode.

## One thought on “Expectation Symbol in LaTeX”

1. Shane

Thanks for the tip. You need to import `\usepackage{amssymb}` in order for this to work.