# Comma in the formula in tikz

I'm trying to compile a picture with the following formula in the label

\begin{tikzpicture}
\node[label=left:$f_{23}(r(x_2,\tau))$] (F012) at (0,2) {};
\end{tikzpicture}


However, every time I put a comma inside the formula, TeX writes me an error message:

Missing \endcsname inserted.
\tau
l.207 \node[label=left:$f_{23}(r(x_2,\tau))$]


I understand that this comma violates some internal rule of tikz, but how can I overcome this problem?

• Have you tried enclosing it with braces? \node[label=left:{$f_{23}(r(x_2,\tau))$}] – clemens Jul 29 '12 at 9:14

\begin{tikzpicture}
\node[label=left:{$f_{23}(r(x_2,\tau))$}] (F012) at (0,2) {};

\pgfkeys{ key list }