Matrix looks flat

Question

I would like to typeset a partitioned matrix in LaTeX with dashed lines. After a quick search on TeX.SE, I found this post with a nice example of such matrices. I tried it on my computer and the result looks "flat". By "flat", I mean that the matrix doesn't look square.

Here is my example :

\documentclass[a4paper,10pt]{article}
\usepackage{arydshln}
\setlength{\dashlinegap}{2pt}

\begin{document}
\[ \Gamma = \left(\begin{array}{c:c} \Gamma_{A} & \Gamma_{AB} \\ \hdashline (\Gamma_{AB})^\top & \Gamma_{B} \end{array} \right) \]
\end{document}

Here is the result of the previous code :

How can I make the matrix look square ?

Answer 1

You can move the lines further apart by specifying arraystretch:

\documentclass[a4paper,10pt]{article}
\usepackage{arydshln}
\setlength{\dashlinegap}{2pt}

\begin{document}

\[
  \Gamma = \left({\renewcommand*{\arraystretch}{1.5}
    \begin{array}{c:c}
      \Gamma_{A} & \Gamma_{AB} \\
      \hdashline
      (\Gamma_{AB})^\top & \Gamma_{B}
    \end{array}}
  \right)
\]

\end{document}

Here I have localised the change to a group containing the array.

An alternative way to tweak this, avoid the delimiters increasing too much is to add inisible vertical rules of appropiate height / depth:

\documentclass[a4paper,10pt]{article}
\usepackage{arydshln}
\setlength{\dashlinegap}{2pt}

\begin{document}

\[
  \Gamma = \left(
    \begin{array}{c:c}
      \vrule width 0pt depth 6pt \Gamma_A & \Gamma_{AB} \\
      \hdashline
      \vrule width 0pt height 12pt (\Gamma_{AB})^\top & \Gamma_{B}
    \end{array}
  \right)
\]

\end{document}

but choosing the correct values here is rather more ad hoc.