%% 
%%  Ein Beispiel der DANTE-Edition
%%  Mathematiksatz mit LaTeX
%%  3. Auflage
%%  Beispiel 06-11-2 auf Seite 113.
%%  Copyright (C) 2018 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[10pt]{exareport}
\pagestyle{empty}
\setlength\textwidth{170.40707pt}
\AtBeginDocument{\setlength\parindent{0pt}
\setcounter{equation}{51}
\setcounter{chapter}{6}\setcounter{section}{11}}
%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
\begin{flalign} z &= f(x,y) \end{flalign}
\numberwithin{equation}{section}
\begin{align}
\bordermatrix{%
   & c & o & l & u & m & n \cr
 l & 1 & 0 & 0 & 0 &\cos \phi&\sin\phi\cr
 i & 0 & 1 & 0 & 0 &-\sin\phi&\cos\phi\cr
 n & 0 & 0 & 1 & 0 &    0    &    0   \cr
 e & 0 & 0 & 0 & 1 &    0    &    0   \cr}
\end{align}
\renewcommand\theequation{\arabic{equation}}
\begin{flalign} y &= f(x) \end{flalign}
\end{document}