# Align numerator and denominator of a fraction

How do I align the numerator and denominator of a fraction? I am looking for something that achieves the following psuedocode:

\frac{a^2 & b}{c & d}


(The b and d should be aligned vertically on top of one another.)

• How should the a^2 and c items be aligned relative to each other? Both left-aligned, centered, or right-aligned, or something else entirely? Please advise. – Mico Jul 18 '15 at 6:40

If you also want a on top of c, you can simply add a \hfill between c and d.

MWE:

\documentclass{article}

\begin{document}
$\frac{a^2 b}{c\hfill d}$
\end{document}


If, instead, you want a^2 on top of c, also add a \hfill before c:

MWE:

\documentclass{article}

\newlength\mylength
\settowidth\mylength{$a^2$}

\begin{document}
$\frac{a^2 b}{\hfill c\hfill d}$
\end{document}


Here's a last possibility, but I don't think it is what you are looking for.

\documentclass{article}

\newlength\mylength
\settowidth\mylength{$a^2$}

\begin{document}
$\frac{a^2 b}{\hfill c d}$
\end{document}


You can get this with mathpartir package. You can use \inferrule for typesetting logical inference rules.

\documentclass{article}
\usepackage{mathpartir}

\begin{document}

\inferrule{a \\ b}{c \\ d}

\end{document}

• Welcome to TeX.SX! As far as I know, mathpartir.sty is not on CTAN, so a pointer to it would make for a better answer. Another minor point: the minimal class should not be used for examples; better using article. – egreg Jul 18 '15 at 5:45