Splitting a large matrix into two arrays with horizontal dots

And I was wondering how to copy that into a TeX code, I'm not sure how to split this matrix properly while including the name of it and having it numbered as one equation (the exact entries are not necessary).

• Where should the equation number be placed: in the first row, the second row, or halfway between the two rows? Please advise.
– Mico
Jul 26 at 18:14
• Next to the bottom half of the matrix (there's more space there) Jul 26 at 18:17

I suggest you embed an aligned[b] environment in an equation environment, so that the equation number gets placed on the bottom row. Then use a

\left( \begin{matrix} ... \end{matrix} \right.


construct in the upper row and a

\right. \begin{matrix} ... \end{matrix} \left)


construct in the lower row.

\documentclass{article} % or some other suitable document class
\usepackage{amsmath}    % for 'aligned' environment

\begin{document}

\begin{aligned}[b] \mathbf{Y}_{\ell}(r) &= \left( \begin{matrix} a & b & 0 \\ c & d & 0 \\ e & f & \rho_0 r^l \\ g & h & 0 \\ 0 & 0 & r^l\\ i & j & k \end{matrix} \right. \ \cdots \\ &\qquad \cdots \ \left. \begin{matrix} l & m & 0 \\ n & o & 0 \\ p & q & r \\ s & t & 0 \\ 0 & 0 & u \\ v & w & 0 \end{matrix} \right) \end{aligned}

\end{document}