Latex: How to write single cross arrow in a 2x2 matrix?

Question

Is there a way to make a version of the diagram provided above?
Thank you very much.

gernot · Accepted Answer

I'm adapting my answer to "How to add arrow in equations and matrix?"; see there for some explanations on how to draw arrows between text elements.

First, typeset the text without arrows.
Wrap all elements, that will be the origin or target of an arrow, into a tikznode command. This assigns a name to the text element and stores its size and position.
Add a tikzpicture environment with the options remember picture,overlay below. It contains the graphical elements, in this case the arrows. Here you will use the names assigned in the previous step.
Run LaTeX at least two times to propagate the information about the nodes and arrows everywhere.

documentclass{article}
usepackage{tikz}
usetikzlibrary{arrows}% only needed for the arrow tip stealth'
newcommandtikznode[3][]{%
  tikz[remember picture,baseline=(#2.base)]
    node[minimum size=0pt,inner sep=0pt,#1](#2){#3};%
}
begin{document}
begin{tabular}{r@{qquad}r}
    tikznode{-x}{$-x$} & tikznode{1}{$1$} [2ex]
    tikznode{2x}{$2x$} & tikznode{3}{$3$} 
    cline{2-2}
                        & $-x$
end{tabular}
begin{tikzpicture}[remember picture,overlay,> = stealth',shorten <= 4pt,shorten > = 4pt]
  draw[->] (-x.east) -- (3.west);
  draw[->] (2x.east) -- (1.west);
end{tikzpicture}
end{document}

F. Pantigny · Answer

Here is a solution with {NiceArray} of nicematrix.
That environment is similar to the classical environment {array} (of array) but creates PGF nodes under the cells of the array. Then, it's possible to use Tikz to draw the required arrows.
documentclass{article}
usepackage{nicematrix}
usepackage{tikz}

begin{document}

$begin{NiceArray}{r@{qquad}r}
    -x & 1 [2ex]
    2x & 3 
    cline{2-2}
         & -x
CodeAfter
begin{tikzpicture}[shorten <= 4pt,shorten > = 4pt]
  draw[->] (1-1.east) -- (2-2.west);
  draw[->] (2-1.east) -- (1-2.west);
end{tikzpicture}
end{NiceArray}$

end{document}

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

Latex: How to write single cross arrow in a 2x2 matrix?

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