# How to typeset boldface ell?

I know that \ell gives me this nice mathematical "calligraphic" letter l, which I want to use throughout my document. However, it is also a common typographic convention that vectors are typeset in boldface as opposed to having a little arrow on top of them.

Hence: How do I get a boldface \ell? Simply enclosing it in \mathbf does not work...

You can use \boldsymbol from the amsbsy package; if you are going to use the symbol very often, then you can define a new command, as in the following example:

\documentclass{article}
\usepackage{amsmath,amsbsy}

\newcommand*\Bell{\ensuremath{\boldsymbol\ell}}

\begin{document}

\Bell

\end{document}

• Two remarks: \ensuremath serves no purpose here; and bm is recommended over amsbsy; it provides \boldsymbol as an alias to \bm (it should be loaded after amsmath). – egreg Jul 23 '17 at 14:39
\documentclass{article}
\begin{document}

$\ell$\boldmath$\ell$\unboldmath

\end{document}


I could only get it to work using:

\usepackage{bm}

\newcommand*\boldell{\pmb{\ell}}

• \pmb is not needed: \bm{\ell} does the job. – egreg Jul 23 '17 at 14:37