# Length of \underbracket with Libertinus Math

The combination of Libertinus Math and \underbracket (provided by mathtools) produces unreasonably large brackets if the argument of \underbracket becomes too long.

(One can probably also argue that in the second to fourth example the bracket is a bit too short.)

The same output occurs with \Uunderbracket (provided by unicode-math) instead of \underbracket. The problem also occurs with \overbracket and \Uoverbracket.

The problem does not occur with \underbrace or \overbrace (but one could again argue that some of the braces are too short).

It this a problem with Libertinus Math (which I would then report to the developer) or a problem with mathtools / unicode-math (in which case I don’t know what to do about it)?

\documentclass[a5paper]{scrartcl}

\usepackage{mathtools}
\usepackage{unicode-math}
\setmathfont{Libertinus Math}

\begin{document}

\noindent\texttt{underbracket}
$\underbracket{a} + \underbracket{ab} + \underbracket{abc} + \underbracket{abcd} + \underbracket{abcde} + \underbracket{abcdeh} + \underbracket{abcdehi} + \underbracket{abcdehik}$
\texttt{Uunderbracket}
$\Uunderbracket{a} + \Uunderbracket{ab} + \Uunderbracket{abc} + \Uunderbracket{abcd} + \Uunderbracket{abcde} + \Uunderbracket{abcdeh} + \Uunderbracket{abcdehi} + \Uunderbracket{abcdehik}$
\noindent\texttt{overbracket}
$\overbracket{a} + \overbracket{ab} + \overbracket{abc} + \overbracket{abcd} + \overbracket{abcde} + \overbracket{abcdeh} + \overbracket{abcdehi} + \overbracket{abcdehik}$
\texttt{Uoverbracket}
$\Uoverbracket{a} + \Uoverbracket{ab} + \Uoverbracket{abc} + \Uoverbracket{abcd} + \Uoverbracket{abcde} + \Uoverbracket{abcdeh} + \Uoverbracket{abcdehi} + \Uoverbracket{abcdehik}$
\texttt{underbrace}
$\underbrace{a} + \underbrace{ab} + \underbrace{abc} + \underbrace{abcd} + \underbrace{abcde} + \underbrace{abcdeh} + \underbrace{abcdehi} + \underbrace{abcdehik}$
\texttt{overbrace}
$\overbrace{a} + \overbrace{ab} + \overbrace{abc} + \overbrace{abcd} + \overbrace{abcde} + \overbrace{abcdeh} + \overbrace{abcdehi} + \overbrace{abcdehik}$

\end{document}

• It seems a problem specific to Libertinus Math. May 6, 2020 at 22:49
• These “large” symbols are pieced together by repeated rules (in the middle). Libertinus Math’s middle rules were rather inconsistently designed (some were too long while some were too short). May 7, 2020 at 18:50