%%
%% The LaTeX Graphics Companion, 2ed (first printing May 2007)
%%
%% Example 7-4-35 on page 503.
%%
%% Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss
%%
%% 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{183.83385pt}
\StartShownPreambleCommands
\usepackage[all,web]{xy}\usepackage{ifthen}
\StopShownPreambleCommands
\begin{document}
\[\renewcommand{\latticebody}{%
\ifthenelse{\latticeA=1}{%
\ifthenelse{\latticeB=1}{\drop{\dir{*}}}%
{\drop{\dir{o}}}}%
{\drop{\dir{x}}}}
\begin{xy}
*\xybox{0;<8mm,4mm>:<4mm,8mm>::
,0,{\croplattice{-6}{6}{-6}{6}%
{-3}{3}{-3.5}{3.5}}%
}="S"
,{"S"+L \ar "S"+R*+!L{z_1}}
,{"S"+D \ar "S"+U*+!D{z_2}}
\end{xy}\]
\end{document}
