4

I have the following matrix:

\documentclass{article} 
\usepackage{amsmath,multirow} 
\begin{document}
\[
\begin{pmatrix}
1 & 0 & 0                             & 0                            \\
0 & 1 & 0                             & 0                            \\
0 & 0 & \multicolumn{2}{l}{\multirow{R}} \\
0 & 0 & \multicolumn{2}{l}{}   
\end{pmatrix}
\]
\end{document}

I would like to know how to put the R in the middle of these four empty cells.

  • Welcome to TeX.SE! – Mico Jun 25 '20 at 4:53
4

Isn't it a block matrix?

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
\begin{pmatrix}
\begin{matrix} 1 & 0 \\ 0 & 1 \end{matrix} &
\begin{matrix} 0 & 0 \\ 0 & 0 \end{matrix} \\
\begin{matrix} 0 & 0 \\ 0 & 0 \end{matrix} &
R
\end{pmatrix}
\qquad
\begin{pmatrix}
\begin{matrix} 1 & 0 \\ 0 & 1 \end{matrix} &
\begin{matrix} 0 & 0 \\ 0 & 0 \end{matrix} \\
\begin{matrix} 0 & 0 \\ 0 & 0 \end{matrix} &
\text{\Large$R$}
\end{pmatrix}
\]
\[
\begin{pmatrix}
0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0
\end{pmatrix}
\qquad
\begin{pmatrix}
0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0
\end{pmatrix}
\]

\end{document}

The bottom row is just for comparison.

enter image description here

  • Thanks a lot, it worked wonderfully. – Edison Santos Jun 25 '20 at 11:29
6

A simple way would be to use the nicematrix package.

\documentclass{article}
\usepackage{nicematrix}
\begin{document}
\[
\begin{pNiceArray}{CCCC}
1 & 0 & 0              & 0 \\
0 & 1 & 0              & 0 \\
0 & 0 & \Block{2-2}{R} &   \\
0 & 0 &                & 
\end{pNiceArray}
\]
\end{document}

4

Raise it into place:

enter image description here

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\[
  \begin{pmatrix}
    1 & 0 & 0 & 0 \\
    0 & 1 & 0 & 0 \\
    0 & 0         \\
    0 & 0 & \multicolumn{2}{c}{\raisebox{.5\normalbaselineskip}[0pt][0pt]{$R$}}
  \end{pmatrix}
\]

\end{document}
4

A solution that keeps the existing pmatrix setup and combines \multicolumn and \multirow directives:

enter image description here

\documentclass{article} 
\usepackage{amsmath,multirow} 
\begin{document}
\[
\begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & \multicolumn{2}{c}{\multirow{2}{*}{$R$}} \\
0 & 0    
\end{pmatrix}
\]
\end{document}

In short, all you need to do is replace \multicolumn{2}{l}{\multirow{R}} in row 3 of your code with \multicolumn{2}{c}{\multirow{2}{*}{$R$}} and delete \multicolumn{2}{l}{} in row 4 of the pmatrix.

  • I tried this method but it did not work somehow. – Edison Santos Jun 25 '20 at 11:28
  • @EdisonSantos - Please clarify what "it did not work somehow" entails. (The method quite evidently worked just fine for the exaxmple shown above.) What, exactly, isn't working? Do you get error and/or warning messages? If so, what do they say? Did you modify the math part somehow? If so, how? Please be specific. – Mico Jun 25 '20 at 11:58

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