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I'm able to draw matrices on LaTeX but I don't know how to put crossing arrows on it as the second matrix in the figure.

Example of what I want

I tried to make it 5 x 5 matrices and put \diagup, \diagdown on diagonals but it didn't seem like a good idea.

N.N.
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Burak
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1 Answers1

30

I once worked out a similar thing with pgf/tikZ (surprise, surprise!) as a solution to a question where else.

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{calc,matrix}

\begin{document}
  \begin{tikzpicture}[>=stealth]
    \matrix [%
      matrix of math nodes,
      column sep=1em,
      row sep=1em
    ] (sarrus) {%
      a_{11} & a_{12} & a_{13} & a_{11} & a_{12} \\
      a_{21} & a_{22} & a_{23} & a_{21} & a_{22} \\
      a_{31} & a_{32} & a_{33} & a_{31} & a_{32} \\
    };

    \path ($(sarrus-1-1.north west)-(0.5em,0)$) edge ($(sarrus-3-1.south west)-(0.5em,0)$)
          ($(sarrus-1-3.north east)+(0.5em,0)$) edge ($(sarrus-3-3.south east)+(0.5em,0)$)
          (sarrus-1-1)                          edge            (sarrus-2-2)
          (sarrus-2-2)                          edge[->]        (sarrus-3-3)
          (sarrus-1-2)                          edge            (sarrus-2-3)
          (sarrus-2-3)                          edge[->]        (sarrus-3-4)
          (sarrus-1-3)                          edge            (sarrus-2-4)
          (sarrus-2-4)                          edge[->]        (sarrus-3-5)
          (sarrus-3-1)                          edge[dashed]    (sarrus-2-2)
          (sarrus-2-2)                          edge[->,dashed] (sarrus-1-3)
          (sarrus-3-2)                          edge[dashed]    (sarrus-2-3)
          (sarrus-2-3)                          edge[->,dashed] (sarrus-1-4)
          (sarrus-3-3)                          edge[dashed]    (sarrus-2-4)
          (sarrus-2-4)                          edge[->,dashed] (sarrus-1-5);

    \foreach \c in {1,2,3} {\node[anchor=south] at (sarrus-1-\c.north) {$+$};};
    \foreach \c in {1,2,3} {\node[anchor=north] at (sarrus-3-\c.south) {$-$};};
  \end{tikzpicture}
\end{document}

If you need help with further adaptations, feel free to ask.

enter image description here

David Carlisle
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Thorsten Donig
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    +1 for the picture. I usually don't teach the Sarrus' rule. – egreg Oct 28 '11 at 15:57
  • Hi! there is a way to transforme your command in a 9-arguments math-command that we can call, for istance, '' \sarrus{arg1}{arg2}{arg3}{arg4}{arg5}{arg6}{arg7}{arg8}{arg9} '' ? @Thorsten Donig – Andrea Leo Oct 14 '16 at 11:45
  • @egreg I want to reproduce the picture. I tried wit align. I want to write D=. Could you please help me? I tried \begin{align*} D & = \begin{tikzpicture}[>=stealth].....but it does not work – Student Jun 26 '21 at 14:54