To be specific, I want to set the following matrix: enter image description here

I already read Draw a box around matrix elements, but I dont know, how one makes a block "T" of this size.

How do I do this?

2 Answers 2


A normal pmatrix from amsmath can serve what you want. To construct that "T block", just use \boxed{~T~}. The tildes ~ are there to make the T wider, and you can also add the superscript 1 by doing \makebox[0pt]{$^1~~$} to cancel its width.

Finally, observe that \setlength\arraycolsep{0pt} for removing spacing between columns only for this matrix.



A = \begin{pmatrix}
\boxed{~T~} &       &        &       \\
            & \tblk &        &       \\
            &       & \ddots &       \\
            &       &        & \tblk 


enter image description here


Since you tag this tikz-matrix, I use one of these. There it is pretty straightforward to put nodes with any desired property.

\[ A=\vcenter{\hbox{
\begin{tikzpicture}[T-block/.style={draw,minimum width=12mm,minimum height=5mm}]
   \matrix (m)[matrix of math nodes,nodes in empty cells,
   left delimiter=(,right delimiter=)]
           |[T-block]| T & & &  \\
           & |[T-block]| T & &  \\
           & & |[T-block,draw=none]|&  \\
           & & & |[T-block]| T  \\
       } ;
        \draw[dotted,thick] (m-2-2)  -- (m-4-4);
        \node[left=0pt of m-2-2.north west,anchor=north east,inner sep=1pt,
        font=\small] {1};
        \node[left=0pt of m-4-4.north west,anchor=north east,inner sep=1pt,
        font=\small] {1};

enter image description here

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