# Shorten fraction line

I understand that this request may sound stupid, but my eyes are just bleeding when I see how $\frac{x^-}{2}$ is rendered: I'm wondering if there's a moderately simple way to make it look like this?

(Please do not suggest $\frac{x^-}{2^{\phantom{-}}}$ or $\frac{{}^{\phantom{-}}x^-}{2}$.)

UPDATE

Well, OK, I've realized that \frac{x}{2}^{-} may work as a temporary solution, but now my eyes are bleeding when looking at the source code.

• How about \frac{x^{\mathmakebox[0pt][l]{-}}}{2} with mathtools?
– user121799
Nov 30, 2018 at 4:28
• Cool, thanks. What exactly is happening here? Nov 30, 2018 at 4:30
• (Even though, it would be preferable to ensure that minus does not stay above the following symbols.) Nov 30, 2018 at 4:30
• Maybe the result of \frac{x^{-}}{2} is not that pretty, but the proposed layout is much worse to my eyes. Nov 30, 2018 at 11:31
• Not only your eyes are bleeding when you look at the code $\frac{x}{2}^{-}$, it gives undesired output in non-display mathmode, especially if the denominator is not a single character, as in $\frac{x}{222}^{-}$. Putting two ~ in front of x does a reasonable job, no matter what the denominator is, as in $\displaystyle \frac{~~x^{-}}{2}$ Dec 5, 2018 at 4:26

My eyes bleed with your proposal. Anyway

\documentclass{article}
\usepackage{amsmath}

\makeatletter
\newcommand{\fracto}{%
{\mathpalette\frac@to{{#1}{#2}{#3}}}%
}
\newcommand{\frac@to}{\frac@@to#1#2}
\newcommand{\frac@@to}{%
% #1 = mathstyle
% #2 = full numerator
% #3 = denominator
% #4 = reduced numerator
\begingroup
\sbox\z@{$\m@th#1\frac{#2}{#3}$}%
\sbox\tw@{$\m@th#1\frac{#4}{#3}$}%
\settowidth\dimen@{$\m@th\frac@to@demote#1#4$}%
\frac{{}\makebox[\dimen@][l]{$\frac@to@demote#1#2$}}{#3}%
\kern-\wd\tw@
\kern\wd\z@
\endgroup
}
\newcommand\frac@to@demote{%
\ifx#1\displaystyle\textstyle\else
\ifx#1\textstyle\scriptstyle\else
\scriptscriptstyle\fi\fi
}
\makeatother

\begin{document}

\begin{gather*}
X + \frac{x^{-}}{2} + \frac{x^{-}}{100} + X \\
X + \fracto{x^{-}}{2}{x} + \fracto{x^{-}}{100}{x} + X \\
\end{gather*}

\end{document} First I typeset the standard fraction, then the same but with the “reduced numerator” in two boxes, so I can use their widths. I also measure the reduced numerator.

Then I typeset the fraction with the numerator having the same width as the reduced one (aligned left). This fraction is as wide as box 2, so I back up by this amount and reinstate the width of the standard fraction, which is the width of box 0.

• Oh God, I will not even ask how this works. Nov 30, 2018 at 18:03
• @mavzolej Added short explanation. Nov 30, 2018 at 18:16

I'll be happy to remove this but you could do

\documentclass{article}
\usepackage{mathtools}
\begin{document}
$\frac{x^{\mathrlap{-}}}{2}\hphantom{-}x$
\end{document} • Not bad! This is smth that can be easily generalised for more complicated cases. Nov 30, 2018 at 4:37