%%
%% An UIT Edition example
%%
%% Example 06-03-22 on page 97.
%%
%% Copyright (C) 2010 Herbert Voss
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See
http://www.latex-project.org/lppl.txt for details.
%%
%%
%% ====
% Show page(s) 1
%%
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{201.70511pt}
\AtBeginDocument{\setlength\parindent{0pt}
\setcounter{equation}{46}
\renewcommand\theequation{6.\arabic{equation}}}
\usepackage{amsmath}
\makeatletter
\def\env@matrix{\hskip -\arraycolsep
\let\@ifnextchar\new@ifnextchar
\array{*\c@MaxMatrixCols r}}% r for right
\renewenvironment{smallmatrix}{\null\,\vcenter\bgroup
\Let@\restore@math@cr\default@tag
\baselineskip6\ex@ \lineskip1.5\ex@ \lineskiplimit\lineskip
\ialign\bgroup\hfil$\m@th\scriptstyle##$%
&&\thickspace\hfil
$\m@th\scriptstyle##$%
\crcr
}{\crcr\egroup\egroup\,}
\makeatother
\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\begin{align}
\begin{pmatrix}
1 &-2 & 1 & 2\\ 2 & 3 &-2 & 3\\
4 &-1 & 3 &-1\\ 3 & 2 &-4 & 5
\end{pmatrix}
\end{align}
\begin{align}
\left(\begin{smallmatrix}
1 &-2 & 1 & 2\\ +2 & 3 &-2 & 3\\
4 &-1 & 3 &-1\\ +3 & 2 &-4 & 5
\end{smallmatrix}\right)
\end{align}
\end{document}
