# Can't make Line-less Fraction

I'm trying to make a line-less fraction to more accurately show vector coordinates. At least my teacher wants us to show them in brackets one above the other like a fraction, but without the fraction line as it isn't a fraction.

I'm using LyX and have been trying to look around on how to get this functionality. It seems that the macro is \bfrac but LyX doesn't know this macro or actually seem to have the ability to do this.

Anyone of you know, how I could solve this?

• Welcome to TeX.SE. Have you tried the plain-TeX macro \atop, e.g., $\left[ {a \atop b} \right]$. Note the special syntax.
– Mico
Oct 7, 2015 at 15:35
• Huh, It was \atop. That's weird, I didn't see that anywhere in the toolbars ._. Thanks dude! If you want to make it an answer I'll accept it :) Oct 7, 2015 at 15:40
• If you got \bfrac from latex-community.org/forum/viewtopic.php?f=46&t=14773 (it is not in standard LaTeX nor amsmath) you will need to copy the \newcommand line into the LaTeX preamble and use an ERT I suppose. Oct 7, 2015 at 15:45
• See my answer tex.stackexchange.com/a/152208/4427 Oct 7, 2015 at 20:53

You may want to use the plain-TeX directive \atop. It uses so-called infix notation. If you end up using \atop a lot, you may want to create a LaTeX-style macro.

\documentclass{article}
\newcommand\myatop[2]{\left[{{#1}\atop#2}\right]} % "wrapper macro"
\begin{document}

%% plain-TeX syntax
$\left[ {u \atop v} \right]$, $\displaystyle \left[ {u \atop v} \right]$

\bigskip
%% LaTeX-type syntax
$\myatop{u}{v}$, $\displaystyle \myatop{u}{v}$

\end{document}


here's another method, based on the amsmath command \genfrac.

\documentclass{article}
\usepackage{amsmath}

\DeclareRobustCommand{\brkbinom}{\genfrac[]{0pt}{}}

\begin{document}
$\brkbinom{a}{b}$, $\displaystyle\brkbinom{a}{b}$
\end{document}


this is actually essentially the same as this answer:
Latex \binom with other types of brackets.

• Or smallmatrix? (Which doesn't scale, I know). Oct 7, 2015 at 20:01