%% 
%%  Der Mathematiksatz mit LaTeX, 1. Auflage 2009
%% 
%%  Example 4-8-11 on page 57.
%% 
%%  Copyright (C) 2009 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.
%% 

\documentclass[]{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{170.59192pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands
\usepackage{setspace}
\newenvironment{Array}[2][1]
  {\setstretch{#1}\array{#2}}
  {\endarray}
\StopShownPreambleCommands
\begin{document}
\[ \begin{Array}[0.75]{|ccc|}
a &=& b\\ 1 &=& y\\ X &=& z
\end{Array} \]

Text $\begin{Array}[2]{|ccc|}
a &=& b\\ 1 &=& y\\ X &=& z
\end{Array}$ Text
\end{document}