A loop like a circle

[Alain Matthes-2]

Hi,

This idea comes when I try to create a graph probabilist
I would a loop but


like an arc of circle



Th idea  was to choice a first node with a shape circle and to design  
two anchors
North east(C) and south east(D) then to build an arc with a center


\documentclass[a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[upright]{fourier}
\usepackage{fullpage}
\usepackage{tikz}
\usetikzlibrary{arrows,calc}

\newcommand{\tikzAngleOfLine}{\tikz@AngleOfLine}
\def\tikz@AngleOfLine(#1)(#2)#3{%
\pgfmathanglebetweenpoints{%
\pgfpointanchor{#1}{center}}{%
\pgfpointanchor{#2}{center}}
\pgfmathsetmacro{#3}{\pgfmathresult}%
}
\thispagestyle{empty}
\begin{document}


\begin{tikzpicture}[>=stealth']
\node [circle,draw](A) {first node};
\coordinate  (C) at (A.north east);
\coordinate  (D) at (A.south east);
\coordinate  (B) at ([xshift=1cm]A);

\tikzAngleOfLine(B)(D){\AngleStart}
\tikzAngleOfLine(B)(C){\AngleEnd}
\draw[red,thick,->]%
    let \p1 = ($ (B) - (D) $), \n2 = {veclen(\x1,\y1)}
    in
      (B) ++(0:\n2) node[fill=white]{$\alpha$}
      (D) arc (\AngleStart-360:\AngleEnd:\n2);
  \end{tikzpicture}

\end{document}

I would to know if it exists a more simple solution

Best Regards

Alain Matthes



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