# Partition Matrices, merge two cells

I have the following code for a MWE:

$D = \left[ \begin{array}{c|c|c} D_{1} & 0 & D_{2} \\ \hhline{-|-|-} D_{3} & & 0 \\ \hhline{~|~} \end{array} \right]$


This results in the first row as desired, but in the second row, it leaves the second spot blank but maintains the vertical line on either side. This is not the desired result. Instead, I am seeking to have the first D3 entry take up the first two spaces with no vertical line in between, then a vertical line, then 0. I am unsure of how to do this and am seeking help.

Like this?

\documentclass[12pt,oneside]{book}

\begin{document}
$D = \left[ \begin{array}{c|c|c} D_{1} & 0 & D_{2} \\ \hline \multicolumn{2}{c|}{D_{3}} & 0 \\ \end{array} \right]$
\end{document}


Addendum: If you like to have more vertical spaces around matrix cells, than you can change \arraystreatch. Foe example as is done inthe following MWE:

\documentclass[12pt,oneside]{book}

\begin{document}
$\renewcommand\arraystretch{1.5}% <--- D = \left[ \begin{array}{c|c|c} D_{1} & 0 & D_{2} \\ \hline \multicolumn{2}{c|}{D_{3}} & 0 \\ \end{array} \right]$
\end{document}