Highlight elements in the matrix (continued)

Question

Using @Stefan Kottwitz's solution of Highlight elements in the matrix, is it possible to select one single entry in the matrix? Where does one need to place the left and the right marks?

Answer 1

For a single element you don't need to use external mechanisms but a node option instead via |[....]|. This will pass the options to the cell as node options. A simple example taken from the linked question:

\documentclass[tikz]{standalone}
\usetikzlibrary{matrix}
\begin{document}
    \begin{tikzpicture}
        \matrix [matrix of math nodes,left delimiter=(,right delimiter=)] (m)
        {
            8 &8 &1 &6 \\
            3 &8 &5 &7 \\
            4 &8 &9 &|[draw=red,fill=blue!10,outer sep=0,inner sep=2pt]|5 \\
        };  
    \end{tikzpicture}
\end{document}