# Spacing between triple vertical lines

I would like to create a norm-like operator with 3 verticals bars instead of two. It has to look like $|||\cdot|||$. I would like to know how to decrease the spacing between the vertical bars such that it has the same spacing as the $\lVert .. \rVert$ command.

There is a command available in the stmaryrd package called \biginterleave, but this command has to much spacing between the vertical bars, especially in display math mode.

Is there some work-around to adjust the spacing between to vertical bars?

\end{document}


A solution using \vvvert of package mathabx. The symbol can also be used with \left and \right. Since the package changes many math symbols, the following example only defines \vvvert and the symbol fonts, needed for it without changing other math symbols:

\documentclass{article}
%\usepackage{mathabx}

% Math symbol font matha
\DeclareFontFamily{U}{matha}{\hyphenchar\font45}
\DeclareFontShape{U}{matha}{m}{n}{
<5> <6> <7> <8> <9> <10> gen * matha
<10.95> matha10 <12> <14.4> <17.28> <20.74> <24.88> matha12
}{}
\DeclareSymbolFont{matha}{U}{matha}{m}{n}
\DeclareFontSubstitution{U}{matha}{m}{n}

% Math symbol font mathb
\DeclareFontFamily{U}{mathx}{\hyphenchar\font45}
\DeclareFontShape{U}{mathx}{m}{n}{
<5> <6> <7> <8> <9> <10>
<10.95> <12> <14.4> <17.28> <20.74> <24.88>
mathx10
}{}
\DeclareSymbolFont{mathx}{U}{mathx}{m}{n}
\DeclareFontSubstitution{U}{mathx}{m}{n}

% Symbol definition
\DeclareMathDelimiter{\vvvert}{0}{matha}{"7E}{mathx}{"17}

\begin{document}
$\left\vvvert \frac{A}{B}\right\vvvert$
\end{document}