# Bold brackets in equations

I want to write an equation with bold extended brackets.

For instance in:

\left[ \frac{1}{2} \vec{\nabla} \times \vec{v} \right]


I want \left[ and \right] to be bold. I already tried https://tex.stackexchange.com/a/99286/15659 nothing is doing the trick.

You can do

\documentclass{article}
\usepackage{bm}
\showoutput
\begin{document}

$[ \vec{\nabla} \times \vec{v} ]$

$\bm{[} \vec{\nabla} \times \vec{v} \bm{]}$

\end{document}


It does not work with \left, \right with the default cm fonts as there is no bold extension font (for large brackets) in that font set. However extended brackets are not needed here.

• The example is bad. I need extended brackets actually. – Kyle_the_hacker Apr 15 '15 at 10:20
• @Kyle_the_hacker cm doesn't have bold extended, so you need to switch fonts or accept they are not bold (or resort to some fake bold over-printing horror:-) – David Carlisle Apr 15 '15 at 10:22
• why the downvote? The answer is correct to report cm doesn't have a bold font for this, "don't shoot the messenger" :-) – David Carlisle Apr 15 '15 at 10:41

Here is the best solution I could found:

\pmb{\left[\vphantom{\frac{1}{2}}\right.}
\frac{1}{2} \vec{\nabla} \times \vec{v}
\pmb{\left.\vphantom{\frac{1}{2}}\right]}


It is dirty, but it does exactly what I want:

• You can define a macro to handle the phantom automatically by defining it as: \pmb{\left[\vphantom{#1}\right.} #1 \pmb{\left.\vphantom{#1}\right]} – Mobius Pizza Apr 15 '15 at 12:47