this is a matrix i tried to add parentheses or brackets to
\begin{array}{cccc|ccc|cc}
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
b_F & a_F & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
0 & v & 0 & v & 0 & 0 & 0 & 0 & 0 \\
c_F & 0 & 0 & 0 & -v & 0 & 0 & 0 & 0 \\
\hline
0 & 0 & 0 & 0 & 0 & v & 0 & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & -3\frac{v}{L} & 3\frac{v}{L} & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
\hline
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & v \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0
\end{array}
this is the result for brackets
\left[ \begin{array}{cccc|ccc|cc}
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
b_F & a_F & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
0 & v & 0 & v & 0 & 0 & 0 & 0 & 0 \\
c_F & 0 & 0 & 0 & -v & 0 & 0 & 0 & 0 \\
\hline
0 & 0 & 0 & 0 & 0 & v & 0 & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & -3\frac{v}{L} & 3\frac{v}{L} & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
\hline
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & v \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0
\end{array}\right]
it may be a little hard to see and since pasting with ":set list" sadly just produces the same output believe me that a level of indentation is added on every line :)
same happens for parentheses and braces and no matter wether line or character visual selection is used