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%%  Ein Beispiel der DANTE-Edition
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%%  1. Auflage
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%%  Beispiel 09-07-40 auf Seite 459.
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%%  Copyright (C) 2011 Herbert Voss
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%%  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.
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% Show page(s) 1
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\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{352.81416pt}
\AtBeginDocument{\setlength\parindent{0pt}
\setcounter{equation}{55}
\renewcommand\theequation{9-\arabic{equation}-}}
\usepackage{blkarray}
\newcommand\bigstrutht{\vrule width0pt height 12pt depth0pt\relax}
\newcommand\bigstrutdp{\vrule width0pt height 0pt depth5pt\relax}
\StartShownPreambleCommands
\usepackage{amsmath,blkarray}
\renewcommand\theequation{\thesection-\arabic{equation}-}
\StopShownPreambleCommands
\begin{document}
\begin{align}\begin{blockarray}{*{4}{c}}
  \begin{block}{[ccc]c}
    \bigstrutht 1-\lambda x & 0 & 0 & \ell_1 \\  0 & 1-\lambda x & 0 & \ell_2 \\
    \bigstrutdp 0 & 0 & 1-\lambda x & \ell_3 \\
  \end{block}
  c_1 & c_2 & c_3
\end{blockarray}\end{align}
\end{document}