How can I make a scaling matrix norm symbol in overleaf with three bars?

Question

How can I write |||A||| with three bars in equal distances that scale? I read through the exiting entries and none of the solutions worked for me, the closest one was with "vertiii" but this put out bars in different sizes.

score 2 · Answer 1 · answered May 27 '21 at 17:36

2

Using barbara's approach at Extensible double angle, etc, which essentially uses triple nested \left| and likewise \right|, with kerning added.

\documentclass{article}
\usepackage{mathtools}
\makeatletter
\def@tvsp{\mathchoice{{}\mkern-4.5mu}{{}\mkern-4.5mu}{{}\mkern-2.5mu}{}}
\def\ltrivert{\left|@tvsp\left|@tvsp\left|}
\def\rtrivert{\right|@tvsp\right|@tvsp\right|}
\makeatother
\newcommand\tnorm[1]{\ltrivert#1\rtrivert}
\begin{document}
[
\tnorm{x}  \tnorm{ \frac{A}{B} }
]
\end{document}

answered May 27 '21 at 17:36

Steven B. Segletes

237,551

Thank you for your answer. Sadly the same problem occurcs. All three lines are in different sizes... – relativeentropy May 30 '21 at 13:46
@milenteor You haven't provided enough information in your question to even attempt to explain why. – Steven B. Segletes May 30 '21 at 15:36
Hello. What additional information do you wish for? It does not work in overleaf, I do get 3 bars but they cascade in size. – relativeentropy Jun 02 '21 at 09:05
@milenteor So that I understand, you say that my MWE, run in overleaf, exhibits this behavior you describe? (FYI, I am not a user of Overleaf) – Steven B. Segletes Jun 02 '21 at 09:10
Yes, exactly. Thank you for pointin this out. – relativeentropy Jun 02 '21 at 09:14
@milenteor That is inexplicable to me, and definitely strange behavior, that three successive \left| (essentially) give different sizes. – Steven B. Segletes Jun 02 '21 at 09:15

score 2 · Answer 2 · answered May 27 '21 at 18:35

The mathabx package defines a \vvvert delimiter. Here is a code to use it without loading the package, based on \DeclarePairedDelimiterX from mathtools:

\documentclass{article}
\usepackage{mathtools}
\usepackage{etoolbox}
\DeclareFontFamily{U}{matha}{\hyphenchar\font45}
\DeclareFontShape{U}{matha}{m}{n}{
<-6> matha5 <6-7> matha6 <7-8> matha7
<8-9> matha8 <9-10> matha9
<10-12> matha10 <12-> matha12
}{}
\DeclareSymbolFont{matha}{U}{matha}{m}{n}
\DeclareFontFamily{U}{mathx}{\hyphenchar\font45}
\DeclareFontShape{U}{mathx}{m}{n}{
<-6> mathx5 <6-7> mathx6 <7-8> mathx7
<8-9> mathx8 <9-10> mathx9
<10-12> mathx10 <12-> mathx12
}{}
\DeclareSymbolFont{mathx}{U}{mathx}{m}{n}
\DeclareMathDelimiter{\vvvert} {0}{matha}{"7E}{mathx}{"17}%
\DeclarePairedDelimiterX{\normiii}[1]
{\vvvert}
{\vvvert}
{\ifblank{#1}{: · :}{#1}}
\begin{document}
[ \normiii[\Big]{A^k } \qquad \normiii{} ]
[ \normiii*{∑_{k \geq 0}^∞ A_k} ]
\end{document}

How can I make a scaling matrix norm symbol in overleaf with three bars?

2 Answers2