# Horizontal line representing row vector in matrix

I would like to produce a graphical representation of a matrix as stack of row vectors. Because I will be publishing the math on a website, I have access to the amsmath package but no others. I find that I can produce a representation of a matrix as a stack of column vectors using the following code

\left(
\begin{array}{ccc}
\vline & \vline & \vline \\
\vline & \vline & \vline \\
\vline & \vline & \vline \\
\end{array}
\right)


What I would like is a transpose of this.

This question is similar to How do I typeset vertical and horizontal lines inside a matrix? and Long dashes for denoting omitted columns of a matrix, but when I apply the approaches found in those posts, I do not obtain a continuous horizontal line.

• Not great, but try \left(\begin{array}{ccc} & & \\ \hline & & \\ \hline & & \\ \hline & & \end{array} \right)
– Vivi
Jun 12, 2012 at 19:02
• Welcome to TeX.SX! Just use one column and say \rule[2.2pt]{4em}{0.4pt} in each row. Here 4em is the width, adjust to suit. Jun 12, 2012 at 19:03
• In essence, what @egreg says is the same as what the accepted answer to the first linked question proposes. Can you say more precisely what your problems with this approach are? Jun 12, 2012 at 19:09
• @egreg Thanks! That would seem to do the trick. Jun 13, 2012 at 21:14
• @Hendrik Yes, I agree now. I think I didn't understand the answer well enough at the time I posted. Jun 13, 2012 at 21:16

Saying simply \vline is not the best method, in my opinion. Try

\documentclass{article}
\usepackage{amsmath}

\begin{document}
$\begin{pmatrix} \kern.6em\vline & \kern.2em\vline\kern.2em & \vline\kern.6em \\ \kern.6em\vline & \kern.2em\vline\kern.2em & \vline\kern.6em \\ \kern.6em\vline & \kern.2em\vline\kern.2em & \vline\kern.6em \\ \end{pmatrix} \begin{pmatrix} \rule[.5ex]{3.5em}{0.4pt}\\ \rule[.5ex]{3.5em}{0.4pt}\\ \rule[.5ex]{3.5em}{0.4pt} \end{pmatrix}$
\end{document} Here is a mild mockup of two different approaches that doesn't require amsmath. The second requires graphicx though. It duplicates your existing column representation, just horizontally: \documentclass{article}
\usepackage{graphicx}% http://ctan.org/pkg/graphicx
\begin{document}
$\left( \begin{array}{ccc} \vline & \vline & \vline \\ \vline & \vline & \vline \\ \vline & \vline & \vline \end{array} \right) \quad \left( \begin{array}{p{3em}} \raisebox{.5ex}{\rule{3em}{.4pt}} \\[\dimexpr-2\normalbaselineskip+2\tabcolsep] \raisebox{.5ex}{\rule{3em}{.4pt}} \\[\dimexpr-2\normalbaselineskip+2\tabcolsep] \raisebox{.5ex}{\rule{3em}{.4pt}} \end{array} \right)$
$\left( \begin{array}{ccc} \vline & \vline & \vline \\ \vline & \vline & \vline \\ \vline & \vline & \vline \end{array} \right) \quad \left( \begin{array}{c} \rotatebox{90}{ \begin{array}{ccc} \vline & \vline & \vline \\ \vline & \vline & \vline \\ \vline & \vline & \vline \end{array}} \end{array} \right)$
\end{document}