# [Tex/LaTex] Upper triangular matrix with big zero in lower triangular

math-modematrices

I can represent an upper trapezoidal matrix say as shown below. I would like to replace all those zeros with a single big zero that spans across the low triangle rows and columns, and maybe also add a delimiter along the diagonal that clearly shows it is an upper diagonal matrix. How can I do that?

\newcommand\x{\XSolid}
%\newcommand\x{\ding{53}}
$$\left( \begin{array}{*5{c}} \x & \x & \x & \x & \x \\ 0 & \x & \x & \x & \x \\ 0 & 0 & \x & \x & \x \\ 0 & 0 & 0 & \x & \x \\ 0 & 0 & 0 & 0 & \x \\ \end{array}\right)$$


Separate question … why the \x command I define outputs # rather than the intended cross symbol? It outputs the same symbol # no matter if I use \XSolid or \ding{53}

UPDATE: taking the answer as input, I ended doing this:

\newcommand\x{\times}
\newcommand\bigzero{\makebox(0,0){\text{\huge0}}}
\newcommand*{\bord}{\multicolumn{1}{c|}{}}
$$\left( \begin{array}{ccccc} \x & \x & \x & \x & \x \\ \cline{1-1} \bord & \x & \x & \x & \x \\ \cline{2-2} & \bord & \x & \x & \x \\ \cline{3-3} & \bigzero & \bord & \x & \x \\ \cline{4-4} & & & \bord & \x \\ \cline{5-5} \end{array}\right)$$


which produces this:

\documentclass[]{article}
$\left( \begin{array}{ccccc} 1 \\ & 1 & & \text{\huge0}\\ & & 1 \\ & \text{\huge0} & & 1 \\ & & & & 1 \end{array} \right)$

or \makebox(0,0){\text{\huge0}} if you want to have the same line spacing.