Representing the following matrix in Katex/HTML [closed]

Question

I need to write this matrix, but how can I make it in KaTeX and HTML?

Answer 1

With a normal array along with \multicolumns this can be quite easy.

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\[
J(2)=\left(\begin{array}{lllll}
\cline{1-1}
\multicolumn{1}{|l|}{2} & 0 & 0                      & 0 & 0                      \\ \cline{1-3}
\multicolumn{1}{l|}{0}  & 2 & \multicolumn{1}{l|}{0} & 0 & 0                      \\
\multicolumn{1}{l|}{0}  & 1 & \multicolumn{1}{l|}{2} & 0 & 0                      \\ \cline{2-5} 
0                       & 0 & \multicolumn{1}{l|}{0} & 2 & \multicolumn{1}{l|}{0} \\
0                       & 0 & \multicolumn{1}{l|}{0} & 1 & \multicolumn{1}{l|}{2} \\ \cline{4-5} 
\end{array}\right)
\]

\end{document}

Answer 2

With {NiceArray} of nicematrix.

\documentclass{article}
\usepackage{nicematrix}

\begin{document}

\NiceMatrixOptions{exterior-arraycolsep}

$J(2) = 
\left(\,\begin{NiceArray}{ccccc}
\Block[draw]{}{}2 & 0 & 0 & 0 & 0 \\
0 & \Block[draw]{2-2}{}2 & 0 & 0 & 0 \\
0 & 1 & 2 & 0 & 0 \\
0 & 0 & 0 & \Block[draw]{2-2}{}2 & 0 \\
0 & 0 & 0 & 1 & 2 
\end{NiceArray}\,\right)$\

\end{document}

You need several compilations (because nicematrix uses PGF/Tikz nodes under the hood).

If you prefer, you can also draw the rules with an Tikz instruction after the content of the matrix. The output is the same.

\documentclass{article}
\usepackage{nicematrix,tikz}

\begin{document}

\NiceMatrixOptions{exterior-arraycolsep}

$J(2) = 
\left(\,\begin{NiceArray}{ccccc}
2 & 0 & 0 & 0 & 0 \\
0 & 2 & 0 & 0 & 0 \\
0 & 1 & 2 & 0 & 0 \\
0 & 0 & 0 & 2 & 0 \\
0 & 0 & 0 & 1 & 2 
\CodeAfter 
  \tikz \draw (1-|1) -| (4-|2) -| (last-|last) -| (2-|4) -| cycle ; 
\end{NiceArray}\,\right)$\

\end{document}

Answer 3

A starting point (without the lines within the matrix).

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation}
J(2) = 
\begin{pmatrix}
2 & 0 & 0 & 0 & 0\\
0 & 2 & 0 & 0 & 0\\
0 & 1 & 2 & 0 & 0\\
0 & 0 & 0 & 2 & 0\\
0 & 0 & 0 & 2 & 1
\end{pmatrix}\,.
\end{equation}
% the "\," adds a small space before the dot.

\end{document}