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.


2 Answers 2


You can do

enter image description here


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

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


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. Commented Apr 15, 2015 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:-) Commented Apr 15, 2015 at 10:22
  • 2
    why the downvote? The answer is correct to report cm doesn't have a bold font for this, "don't shoot the messenger" :-) Commented Apr 15, 2015 at 10:41

Here is the best solution I could found:

\frac{1}{2} \vec{\nabla} \times \vec{v}

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

enter image description here

  • 2
    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]} Commented Apr 15, 2015 at 12:47

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