%% 
%%  A DANTE-Edition example
%% 
%%  Example 02-04-6 on page 40.
%% 
%%  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[]{article}
\pagestyle{empty}
\setlength\textwidth{201.70511pt}
\setlength\parskip{10pt}
\AtBeginDocument{\setbox0\hbox{$ $}}

\usepackage{blkarray}

\begin{document}
\begin{blockarray}{>{\scriptsize}ccccl}
\begin{block}{*{5}{>{\scriptsize}c}}
1 & 2 & 3 & 4 & columns\\
\end{block}
\begin{block}{\Left{demo} \{ >{\scriptsize}cccc
     \Right\}{3$\times$3 matrix} l}
2 & 22 & 32 & 42\\ 3 & 23 & 33  & 43\\
4 & 24 & 34 & 44\\
\end{block}
\makebox[0pt][l]{\scriptsize rows}
\end{blockarray}
\end{document}