# Split within a matrix environment

I have an array that looks like this:

I'm not sure how I can add the curly brackets and text there.

I formatted the array like this:

\begin{equation*}
\begin{array}{r*{10}{l}}
\trom{1} & 2 + x_1 -2 = x_1 & \\
\trom{2} & 1 + 2s + 0t = x_2 & \\
& 1 + 2s = x_2 \\
\trom{3} & 0 + 2s + 3t = x_3 \\
& \text{Some more calculations}
\end{array}
\end{equation*}


I tried to use the split environment within the array environment:

\begin{equation*}
\begin{array}{r*{10}{l}}
\left .
\begin{split}
\trom{1} & 2 + x_1 -2 = x_1 & \\
\trom{2} & 1 + 2s + 0t = x_2 & \\
& 1 + 2s = x_2 \\
\end{split}

\right \} \textit{Test....}
\\

\trom{3} & 0 + 2s + 3t = x_3 \\
& \text{Some more calculations}

\end{array}
\end{equation*}


But that messes up the "grid":

How can I use the split environment within an array environment? If that's not possible (or if there's a more elegant way), please post it instead.

split is not intended to be used in that way, you really want aligned instead.

\documentclass{article}

\usepackage{mathtools}

\newcommand{\trom}[1]{\makebox[0pt][r]{\MakeUppercase{\romannumeral #1}}}

\begin{document}

\begin{equation*}
\begin{split}
&\!\left .  \!\begin{aligned}
\trom{1}\quad & 2 + x_1 -2 = x_1  \\
\trom{2}\quad & 1 + 2s + 0t = x_2  \\
& 1 + 2s = x_2 \\
\end{aligned}
\right \} \textit{Test....}
\\
&\trom{3}\quad  0 + 2s + 3t = x_3 \\
\end{split}
\end{equation*}

\end{document}

• Thanks. That's what I've been looking for. I still have a question, though. Why did you add \!? A google search for Latex exclamation point|mark didn't turn up anything useful. May 15, 2015 at 17:54
• Never mind. I just found it in another answer. May 15, 2015 at 18:20

Here is another option using arrays:

\documentclass{article}

\usepackage{amsmath}
\newcommand{\toRoman}[1]{\text{\MakeUppercase{\romannumeral #1}}}
\begin{document}

\begin{equation*}
\renewcommand{\arraystretch}{1.2}% http://tex.stackexchange.com/a/31704/5764
\begin{array}{r l}
\multicolumn{2}{l}{\left.\kern-\nulldelimiterspace\begin{array}{@{}r l}
\hphantom{\toRoman{3}}\makebox[0pt][r]{\toRoman{1}} & 2 + x_1 -2 = x_1 \\
\toRoman{2} & 1 + 2s + 0t = x_2 \\
& 1 + 2s = x_2