Writing a matrix over two lines

\documentclass{article}
\usepackage{mathtools}
\def\mtrm#1{\rule{#1}{1.5ex}}

\begin{document}

\begin{multline}
\bar{L}_2 = \left(
  \begin{matrix}
    \mtrm{15ex} & \mtrm{15ex}\\ 
    \mtrm{7ex}  & \mtrm{7ex} \\ 
    \mtrm{4ex}  & \mtrm{4ex} \\ 
    \mtrm{18ex} & \mtrm{18ex}\\
  \end{matrix}\right.                
\\
  \left.
  \begin{matrix}
    \mtrm{16ex} & \mtrm{6ex} \\ 
    0           & 0          \\ 
    \mtrm{4ex}  & \mtrm{14ex}\\ 
    \mtrm{19ex} & \mtrm{19ex}
  \end{matrix}\right)
\end{multline}

\end{document}

\documentclass{standalone}

\begin{document}
    \begin{tabular}{ccc}
        $L=$ & $\left( \begin{tabular}{c}A\\B\\C\\D\\\end{tabular} \right.$ & $\begin{tabular}{c}E\\F\\G\\H\\\end{tabular}$ \\
        & $\begin{tabular}{c}I\\J\\K\\L\\\end{tabular}$ & $\left. \begin{tabular}{c}M\\N\\O\\P\\\end{tabular} \right)$\\
    \end{tabular}
\end{document}

One can also use \substack:

Notes:

• The matrix used here is from I want to write an element of a matrix on two lines is possible.
• Corrected use of \sin, \cos and defined a macro for the font selection.

Code:

\documentclass{article}

\newcommand{\MyFont}[1]{\textrm{\fontfamily{lmr}\fontshape{ui}\selectfont #1}}

\usepackage{mathtools}

\begin{document}
$\tilde{A}_{Long}=\begin{pmatrix}
X_{\MyFont{u}}&X_{\MyFont{w}}&X_q-M_{33}\MyFont{w}_0&-(mg-B_u)\cos(\theta_0)\\[1.0ex]
Z_{\MyFont{u}}&Z_{\MyFont{w}}&Z_q-M_{11}\MyFont{u}_0&-(mg-B_u)\sin(\theta_0)\\[1.0ex]
M_{\MyFont{u}}&M_{\MyFont{w}}
    &\substack{M_{q}-M_{11}.x_G\MyFont{u}_0 \\ -M_{33}.z_G\MyFont{w}_0}
    &\substack{\hphantom{-}(x_Gmg+x_BB_u)\sin(\theta_{0})\\ -(z_Gmg+z_BB_u) \cos(\theta_{0})} 
    \\[1.0ex]
 0&0&1&0\\
\end{pmatrix}$
\end{document}