evdpgf.tex

\documentclass{article}
\title{Edwards-Venn Diagrams with PGF}
\author{Matthew Leingang}
\usepackage{tikz}
\usepackage{fp}

% This is to recreate the Edwards-Venn Diagrams such as I found in
% chapter 4 of "Another Fine Math you Got me Into...

%% From Alain Matthes
%% http://www.nabble.com/TikZ-for-geometric-drawings--tf3210067.html#a8914364
%\makeatletter
%\newcommand*{\extractvect}[2]{%  \vx et \vy
%\pgfextractx{\pgf@x}{\pgfpointanchor{#1}{center}}
%\pgf@xa=\pgf@x%
%\pgfextracty{\pgf@y}{\pgfpointanchor{#1}{center}}
%\pgf@ya=\pgf@y%
%\pgfextractx{\pgf@x}{\pgfpointanchor{#2}{center}}
%\pgfextracty{\pgf@y}{\pgfpointanchor{#2}{center}}
%\advance\pgf@x by-\pgf@xa\relax%
%\advance\pgf@y by-\pgf@ya\relax%
%\global\expandafter\edef\csname tkz@vx\endcsname{\the\pgf@x}%
%\global\expandafter\edef\csname tkz@vy\endcsname{\the\pgf@y}
%}

%\newdimen\@tmplen
%% longueur entre deux noeuds
%\newcommand*{\dist}[2]{
%\extractvect{#1}{#2}
%\@tmplen=\tkz@vx
%\edef\@vx{\strip@pt\@tmplen}%
%\FPmul\@vxc{\@vx}{\@vx}
%\@tmplen=\tkz@vy
%\edef\@vy{\strip@pt\@tmplen}%
%\FPmul\@vyc{\@vy}{\@vy}
%\FPadd{\@sdc}{\@vxc}{\@vyc}
%\FProot{\@sdc}{\@sdc}{2}
%\global\let\@sdc\@sdc
%}

%
%\define@cmdkey[TKZ]{tkzcc}{pos}{}
%\define@cmdkey[TKZ]{tkzcc}{color}{}
%\define@cmdkey[TKZ]{tkzcc}{size}{}
%\define@cmdkey[TKZ]{tkzcc}{style}{}
%\presetkeys[TKZ]{tkzcc}{color = black,%
%                          size  = 0.8 pt,%
%                          pos   = above}{}

%\newcommand*{\tkzcc}[1][]{\tkz@cc[#1]}%
%\def\tkz@cc[#1](#2,#3){%
%\dist{#2}{#3}
%\draw[] (#2) circle (\@sdc pt);}

%\newcommand*{\tkzarcc}[1][]{\tkz@arcc[#1]}%
%\def\tkz@arcc[#1](#2:#3:#4:#5){%
%\dist{#4}{#5}
%\draw[#1] (#4) arc (#2:#3:\@sdc pt);}

% 2007-04-29
% Now that I understand the FP package, it should be easier than I 
% thought.  Use that to compute the radii and angles for pi divided by each
% power of two.

 
\makeatother

\begin{document}
\begin{center}
\begin{tikzpicture}[scale=3]
\draw (0,0) coordinate (O) circle (1cm);
\draw (45:1) node (A) {$\bullet$} node[above right] {$A$};
\draw (-45:1) node (B) {$\bullet$} node[above right] {$B$};
\draw (A) +(-45:1) node (C) {$\bullet$} node[above right] {$C$};
\draw (B) arc (-135:135:1);
\draw (A) arc (-45:-135:1);
\end{tikzpicture}
\end{center}
\end{document}