%% The LaTeX Graphics Companion, 2ed (first printing May 2007)

%%
%% The LaTeX Graphics Companion, 2ed (first printing May 2007)
%%
%% Example 7-3-2 on page 476.
%%
%% 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[curve]{xy}
\StopShownPreambleCommands
\begin{document}
\[\begin{xy}
0*+{L};(50,20)*+{R}
**\crv{~*=<2mm>{.}(20,30)&(30,35)}
**\crv~Lc{~**@{==}~*{\bullet}%
(20,-15)&(30,-15)}
\end{xy}\]

\end{document}