arydshln not working well with multicolumn

Question

I am having some problems with arydshln and multicolumn. The following document:

\documentclass{article}
\usepackage{amsmath}
\usepackage{arydshln}

\begin{document}
\[
        \begin{pmatrix}
        \multicolumn{1}{|c|}{1}  & \multicolumn{1}{|c|}{2}   & \multicolumn{1}{|c|}{3} & \multicolumn{1}{|c|}{4}\\[5ex] \cline{1-4}
        \end{pmatrix}
\]
\end{document}

generates this output:

with the vertical lines too short. If I remove the \usepackage{arydshln} line, the output is fine:

So arydshln doesn't seem to work well with multicolumn and the [5ex] height spec, it seems.

The same happens if I use multicolumn with {:c:} for alignment (which is actually what I wanted, and won't work):

\multicolumn{1}{:c:}{1}  & \multicolumn{1}{:c:}{2}   & \multicolumn{1}{:c:}{3} & \multicolumn{1}{:c:}{4}\\[5ex] \cdashline{1-4}

So is there a way to get the second result? Am I using the packages the wrong way?

Thank you!

Answer 1

In my point of view it's better to provide a real tabular environment inside of the pmatrix environment -- it works out of the box then!

\documentclass{article}
\usepackage{amsmath}
\usepackage{arydshln}

\begin{document}
\[
\begin{pmatrix}
  \begin{tabular}{:*{4}{c:}}
    1 & 2 & 3 & 4 \tabularnewline
    &   &   &   \tabularnewline[4ex]
    \cdashline{1-4} % or \hdashline
  \end{tabular}
\end{pmatrix}
\]
\end{document}

Answer 2

It's not really clear what your aim is, but you should use a regular array environment:

\documentclass{article}
\usepackage{amsmath}
\usepackage{arydshln}

\begin{document}
\[
\left(\,
\begin{array}{:*{4}{c:}}
1 & 2 & 3 & 4 \\[5ex]
&   &   &   \\
\cdashline{1-4}
\end{array}
\,\right)
\]
\end{document}