Stretching left, "inside" and right delimiters

Question

The following MWE shows a way to stretch left, "inside" and right delimiters. Is the use of \vphantom the good way to do that?

\documentclass{article}
\usepackage{amsmath}
\NewDocumentCommand\interlike{mm}{
  \left[ \vphantom{#2}#1 \right|\left.\vphantom{#1} #2 \right>
}
\begin{document}
$\interlike{\dfrac{X^X}{p_p}}{z}$
$\interlike{z}{\dfrac{X^X}{p_p}}$
\end{document}

score 5 · Accepted Answer · answered Aug 30 '23 at 21:05

I'd prefer the mathtools way.

\documentclass{article}
\usepackage{amsmath,mathtools}
\DeclarePairedDelimiterX{\interlike}[2]{\lbrack}{\rangle}{%
  #1 ,\delimsize|, #2%
}
\begin{document}
\begin{gather}
\interlike{a}{b} \
\interlike[\big]{a}{b} \
\interlike[\Big]{a}{b} \
\interlike{\frac{X^X}{p_p}}{z} \
\interlike[\bigg]{z}{\frac{X^X}{p_p}}
\end{gather*}
\end{document}

See the documentation for \DeclarePairedDelimiterX for more details.

I was about to rebuild the Moon... :-) – projetmbc Aug 30 '23 at 21:26 — projetmbc, Aug 30 '23 at 21:26

score 4 · Answer 2 · answered Aug 30 '23 at 19:39

It works, but the spacing is off, and not because of the \vphantom. It's better to use \middle for this, which works with a \left...\right pair:

\documentclass{article}
\usepackage{amsmath}
\NewDocumentCommand{\interlike}{m m}{%
  \left[ \vphantom{#2}#1 \right|\left.\vphantom{#1} #2 \right]
}
\NewDocumentCommand{\newinterlike}{m m}{%
  \left[ #1 \middle| #2 \right]
}
\begin{document}
$\interlike{\dfrac{X^X}{p_p}}{z}$
$\newinterlike{\dfrac{X^X}{p_p}}{z}$
$\interlike{z}{\dfrac{X^X}{p_p}}$
$\newinterlike{z}{\dfrac{X^X}{p_p}}$
\end{document}

Thanks for pointing me to the middle of your proposition... :-) I had never seen this before... Good point also for the spacing issue. — projetmbc, Aug 30 '23 at 19:43

Stretching left, "inside" and right delimiters

2 Answers2