[Tex/LaTex] Arrows coordinates in TikZ

Question

I want to write a macro that uses TikZ to create a photo like this:

_{(source: msdn.com)} .

But, finally I came up with something like this:

As you see, the problem is that the arrows go to the wrong side of the end circle (they always go to the right side). Here is the source code of my example:

\documentclass[11pt]{scrartcl}
\usepackage[utf8]{inputenc}  
\usepackage{tikz}
\usetikzlibrary{calc} 
\makeatletter 
\@namedef{color@1}{red!40}
\@namedef{color@2}{green!40}   
\@namedef{color@3}{blue!40} 
\@namedef{color@4}{cyan!40}  
\@namedef{color@5}{magenta!40} 
\@namedef{color@6}{yellow!40}    

\newcommand{\graphitemize}[1]{%
\begin{tikzpicture}[every node/.style={align=center}]  

\foreach \gritem [count=\xi] in {#1}  {\global\let\maxgritem\xi}  

\foreach \gritem [count=\xi] in {#1}
{% 
\pgfmathtruncatemacro{\angle}{360/\maxgritem*\xi}
\edef\col{\@nameuse{color@\xi}}
\node[circle,
     ultra thick,
     draw=white,
     fill opacity=.5,
     fill=\col,
     minimum size=3cm] (satellite\xi) at (\angle:4cm) {\gritem };
}%

\foreach \gritem [count=\xi] in {#1}
{% 
\pgfmathsetmacro{\xj}{mod(\xi, \maxgritem) + 1}
\edef\col{\@nameuse{color@\xi}}
\draw[<-,line width=.5cm,opacity=.5,\col] (satellite\xj) to[bend left] (satellite\xi);
}%
\end{tikzpicture}  
}%

\begin{document}

\graphitemize{Phase 1,Phase 2, Phase 3, Phase 4}

\end{document} 

Note that I adapted the code from Altermundus answer to this question. How can I fix the end position of the arrows?

Answer 1

The problem comes from the math operation mod(\xi, \maxgritem) + 1. TikZ is giving the result with a number with decimal point such as 1.0, 2.0 etc. and later since you use it in the node naming it becomes satellite1.0,satellite2.0. Coincidentally, this means that the arrow shoud go to the node border at zero angle, hence the weird right side tracking.

You can fix it easily by replacing the operation line with

\pgfmathtruncatemacro{\xj}{mod(\xi, \maxgritem) + 1)}