How to writing "Double brace" in LaTeX

[chin_b]

Who knows that how to writing "Double Brace" using LaTeX ? Please help
me.

Explanatin: the "Double Brace" usually use in wave propagation to
show the "jump" or "shock condition" at wavefront,
for example, jump of v is [[v]].

[Daniel Koeb]

Post by chin_b
Explanatin: the "Double Brace" usually use in wave propagation to
show the "jump" or "shock condition" at wavefront,
for example, jump of v is [[v]].

Sounds as if you're looking for double bracket, not brace:

\documentclass{article}
\usepackage{stmaryrd}
\begin{document}
$\llbracket v\rrbracket$
\end{document}


HTH
Daniel