Does anyone know how to produce a half-box symbol in LaTeX which comprises a bar over an entire expression and a vertical line on the right meeting in the corner, like the top and the right edge of a box?

I currently use \overline{abc}\vert as a compromise (say, abc is the text I wish to enclose) but clearly the bar and the vertical line do not meet each other in the top-right corner.



3 Answers 3


You probably want an actuarial symbol annuity. One of the solutions is the following macro, taken from ftp://ftp.mackichan.com/swandswp30/support/actuarial.tex,‎ with the usage {\bx argument}:



\def\BX#1{\setbox\tmp=\hbox{$\overline{\scriptstyle #1}$}
              \advance\dropdist by .7pt
              \advance\height by \dp\tmp
              \lower \dropdist \hbox{\vrule height
              \height width .25pt\relax}

{\bx x+y+z\,}

enter image description here

If it will not be used in such a context, some modifications are needed, in particular remowing \scriptstyle before an argument.

  • That's brilliant. It was indeed for typesetting an actuarial science document which I am helping out with.
    – user42427
    Dec 9, 2013 at 8:58
  • 6
    The rules have different widths. There are far better solutions around
    – egreg
    Dec 9, 2013 at 9:00
  • @egreg Yes, these solutions look nicer. However, for some reason the author made such a box. With the suggested knowledge OP can seek for the best solution. And an argument only for fun: the hunting for two gold badges begun. ;-) Dec 11, 2013 at 16:30

A TikZ approach.



  \tikz[baseline=(n.base)]{\node(n)[inner sep=1pt]{$#1$};
    \draw[line cap=round](n.north west)--(n.north east)--(n.south east);




enter image description here


The following takes most of the elements from the LaTeX kernel \framebox to construct a \halfbox:

enter image description here




\fbox{abc}\ \halfbox{abc}


Since it uses the same construction as \framebox, lengths \fboxrule and \fboxsep can be adjusted in the same way.

  • 1
    this would look nicer if there wasn't quite so much white space between the rules and the expression. Dec 9, 2013 at 15:36

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