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The other day I was reading a rather old math book. I noticed it uses a different typeset style to represent a conjugate matrix as shown below in the attached picture. Is there a way to do this in LaTEX? enter image description here

5

Maybe using \overbracket and \underbracket from the mathtools package.

\documentclass{article}
\usepackage{mathtools}
\newcommand\conj[1]{%
  \overbracket[.4pt][1pt]{%
    \underbracket[.4pt][1pt]{\mkern2mu#1\mkern2mu}%
  }\nolimits}
\begin{document}

$A' = \conj{a}_n^m$

\end{document}

enter image description here

Or with Lua/XeLaTeX and unicode-math

\documentclass{article}
\usepackage{unicode-math}
\newcommand\conj[1]{%
  \mathop{%
    \Umathaccent 7\symoperators "023B4{%
      \Umathaccent bottom 7\symoperators "023B5{%
        \mkern2mu#1\mkern2mu
      }%
    }%
  }}
\begin{document}

$A' = \conj{a}_n^m$

\end{document}

enter image description here

2
  • Thank you. I use TeXLive and it works. However, is there a way to adjust the bracket legs to make shorter like the one shown using the Lua/XeLaTeX? – user91822 Nov 27 '18 at 4:00
  • @user91822 See the updated answer. – Henri Menke Nov 27 '18 at 4:19
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Older books are abundant in notation that's no longer used.

With rotated brackets:

\documentclass{article}
\usepackage{amsmath}
\usepackage{graphicx}

\makeatletter
\newcommand{\over@bracket}[1]{%
  \vbox{\m@th\ialign{\hfil##\hfil\cr
    \rotatebox[origin=bl]{90}{$\rbrack$}\cr
    \noalign{\nointerlineskip\vskip1pt}
    #1\vphantom{$by$}\cr
  }}%
}
\newcommand{\under@bracket}[1]{%
  \vtop{\m@th\ialign{\hfil##\hfil\cr
    #1\cr
    \noalign{\nointerlineskip}
    \rotatebox[origin=bl]{90}{$\lbrack$}\cr
  }}%
}
\newcommand{\transpose}[1]{%
  \mathinner{\under@bracket{\over@bracket{$#1$}}}%
}
\makeatother

\begin{document}

\begin{gather*}
% to see the baseline
\rlap{\vrule height 0pt depth 0.1pt width 3cm}
A' + B' = \transpose{a}^{m}_{n} + \transpose{b}^{m}_{n}
\\
A' + B' = \transpose{a}^{m}_{n} + \transpose{b}^{m}_{n}
\\
\transpose{a}\transpose{b}\transpose{y}\transpose{m}
\end{gather*}

\end{document}

enter image description here

2
  • This works OK with a single character as shown in your attached picture. Unfortunately, it does NOT work to show a transpose of an mxn matrix, i.e. the size of both the over/under brackets remains the same as shown in your attached picture and doesn't get stretched to cover all elements of the matrix. – user91822 Nov 27 '18 at 12:53
  • @user91822 That's indeed a completely different matter. I based on the single picture you showed. – egreg Nov 27 '18 at 12:54

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