I am trying to put piece-wise functions into nodes in a Tikz diagram. Using cases works fine in a Tikz node that is separate within a tikzpicture environment. Putting the same node in a matrix breaks the use of & to divide a single line within the cases block.
Is there any way to get the output of the node inside the matrix to match that of the separate node?
\documentclass{article}
\usepackage{tikz, amsmath}
\usetikzlibrary{shapes, positioning}
\begin{document}
\tikzstyle{block} = [draw, rectangle, align=center]
\begin{tikzpicture}
\node[block] (b1) {Separate node:\\
\(
u_{out}=
\begin{cases}
255 & \mbox{if } u_{in} > 255
\end{cases}
\)};
\matrix[below=of b1] (m)
{
\node[block] (b2) {Node in matrix:\\
\(
u_{out}=
\begin{cases}
255 & \mbox{if } u_{in} > 255
\end{cases}
\)};\\
};
\end{tikzpicture}
\end{document}