multiline graphviz node with math mode

Question

I have a node which represents a multiline label in math mode. However, I failed to include the newline symbol \n into the node label. Here is my try

\begin{dot2tex}[neato,scale=.5,options=-t math]
digraph G
{
c[shape=none,label="x_1",pos="1,.25!"];
d[label="D",pos=".5,-1.6!"];


}
\end{dot2tex}

How can I add newline for the node c?

Answer 1

I found the solution here by using matrix package from tikz

\begin{dot2tex}[neato,scale=.8,options=-t math]
digraph G
{
c[shape=none,texlbl="$
\begin{matrix}
x_1
\\ x_2
\end{matrix}$"
,pos="1,-1.2!"];

}
\end{dot2tex}

will add node with two lines $x_1$ and $x_2$.