# '\underline' & '\underbar' (if exists)?

I met a problem in equation editing:

The problem is that the underline is too long comparing with the bar over the letter. So I am wondering is there any symbol like \underbar so that I can get a bar under the characters which is of the same length as the over bar.

• $$\underbar$$ why doesn't it work here? is it possible to put it in math exchange somehow? – Charlie Parker Sep 27 '18 at 0:14

If you use \overline instead of \bar the lines will appear more even.

ETA: The \doublebar macro

\newcommand{\doublebar}[2][0]{\skew#1\bar{\textit{\b #2}}}

will perform the trick I mentioned in the comment; the optional argument is the skew factor for the top bar. E.g., \doublebar{F} or \doublebar[7]{F}.

• Thanks @Jon. Actually, I want the underline to be smaller. It looks wierd like that using an underline. Do you have any idea? – user123 Dec 12 '15 at 3:34
• @David There's the Plain TeX \b, but that's reserved for text mode. Something like \skew5\bar{\textit{\b K}} will do the trick. I put in a skew to make the bars look more in-line with each other. – Jon Dec 12 '15 at 3:59
• $$\underbar$$ why doesn't it work here? is it possible to put it in math exchange somehow? – Charlie Parker Sep 27 '18 at 0:14

You can use a tikz-based solution: Play around with the distances to achieve the desired look. I personally would shift the overline a bit to the right because of the slanting of the math font.

\documentclass{standalone}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{calc}

\newcommand{\tikzul}[2][2pt]{
\tikz[baseline=(content.base)]{
\node(content)[inner sep=0pt]{$#2$};
\draw($(content.south west)+(#1,-1pt)$)--($(content.south east)-(#1,1pt)$);
}
}
\newcommand{\tikzol}[2][2pt]{
\tikz[baseline=(content.base)]{
\node(content)[inner sep=0pt]{$#2$};
\draw($(content.north west)+(#1,1pt)$)--($(content.north east)-(#1,-1pt)$);
}
}
\begin{document}
0: $\tikzul[0pt]{\tikzol[0pt]{K}}*\tikzul[0pt]{\tikzol[0pt]{D}} = \tikzul[0pt]{\tikzol[0pt]{E}}$, 1:
$\tikzul[1pt]{\tikzol[1pt]{K}}*\tikzul[1pt]{\tikzol[1pt]{D}} = \tikzul[1pt]{\tikzol[1pt]{E}}$, 2:
$\tikzul{\tikzol{K}}*\tikzul{\tikzol{D}} = \tikzul{\tikzol{E}}$

\end{document}


• $$\underbar$$ why doesn't it work here? is it possible to put it in math exchange somehow? – Charlie Parker Sep 27 '18 at 0:14