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%%  An UIT Edition example
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%%  Example 10-03-2 on page 202.
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%%  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.
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% Show page(s) 1
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\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\setcounter{equation}{1}
\renewcommand\theequation{10.\arabic{equation}}
\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\begin{equation}
\begin{array}{rcl}
\underline{RS} & = & \left(\begin{array}{*8c}
01 & a4 & 55 & 87 & 5a & 58 & db & 9e\\ a4 & 56 & 82 & f3 & 1e & c6 & 68 & e5\\
02 & a1 & fc & c1 & 47 & ae & 3d & 19\\ a4 & 55 & 87 & 5a & 58 & db & 9e & 03
\end{array}\right)\\~\\
\left(\begin{array}{c}  s_{i,0}\\  s_{i,1}\\  s_{i,2}\\  s_{i,3}
\end{array}\right) & = & \underline{RS} \times
\left(\begin{array}{c}  m_{8i+0}\\ m_{8i+1}\\ \cdots\\ m_{8i+6}\\ m_{8i+7}
\end{array}\right)\\~\\
  S_{i} & = & \sum_{j=0}^{3}s_{i,j}\times2^{8j}\qquad i=0,1,...,k-1\\
  S & = & \left(S_{k-1},S_{k-2},...,S_{1},S_{0}\right)
\end{array}
\end{equation}
\end{document}