# Latex label right and left side of augmented matrix

How do I label both the right and left side of a augmented matrix ?

begin{document}
$\left[ \begin{array}{ccc|c} a & b & c & d\\ a & b & c & d\\ a & b & c &d \\ \end{array} \right] [\begin{array}{l} R_{1} \\ R_{2a} \\ R_{3a} \end{array}$
\end{document}


I have tried this which allows me to label the right side but not sure how to label the left

• Welcome to TeX.SE. It would be helpful if you composed a fully compilable minimal working example (MWE) including \documentclass and the appropriate packages that sets up the problem. While solving problems can be fun, setting them up is not. Then, those trying to help can simply cut and paste your MWE and get started on solving the problem. – user36296 Dec 12 '18 at 1:28

Perhaps the following works for you:

\documentclass{article}

\usepackage{array}

\newenvironment{rowlabels}{
\begin{array}{ @{} >{\scriptstyle}l @{} }
}{
\end{array}
}

\begin{document}

$\begin{rowlabels} L_1 \\ L_{2a} \\ L_{3a} \end{rowlabels} \left[ \begin{array}{ @{} c c c | c @{} } a & b & c & d \\ a & b & c & d \\ a & b & c & d \\ \end{array} \right] \begin{rowlabels} R_1 \\ R_{2a} \\ R_{3a} \end{rowlabels}$

\end{document}


The new environment rowlabels sets a regular array with the elements in \scriptstyle.

\documentclass{article}
\usepackage{blkarray}
\begin{document}

$\begin{blockarray}{c[ccc|c]c} L_1 & a & b & c & d & R_1\\ L_2 & a & b & c & d & R_2\\ L_3 & a & b & c & d & R_3\\ L_4 & a & b & c & d & R_4\\ \end{blockarray}$

\end{document}