Math & Science ⇒ How to type complexity equation in overleaf

[Ethan_Tran]

I tried to type an equation below in Overleaf. Please help me with how I could type it.
Thank you all,

[agsh]

Hello!

You need use nicematrix package. It definitelly can do such matrices.

https://ctan.org/pkg/nicematrix

Unfortunatelly, I'm not LaTeX professional, so this is the best I can do, sorry.

Code: Select all

\documentclass{article}

\usepackage{tikz}
\usepackage{nicematrix}

\begin{document}

$$
    \begin{pNiceArray}{ccccccccc}[first-row,first-col]
        & n + 1 & \cdots & n + m & 1 & \cdots & m & m +1 & \cdots & n \\
        {n + 1}& \Block[borders={bottom, right, tikz={dashed}}]{3-3}{\vec a} & & &
               \Block[borders={bottom, right, tikz={dashed}}]{3-3}{\vec b} & & &
               \Block[borders={bottom, tikz={dashed}}]{3-3}{\vec c} & & \\
        {\Vdots} & & & & & & & & & \\
        {n + m} & & & & & & & & & \\
        {1} & \Block[borders={bottom, right, tikz={dashed}}]{3-3}{\vec x} & & & \Block{6-6}{\vec a} & & & & & \\
        {\Vdots} & & & & & & & & & \\
        {m} & & & & & & & & & \\
        {m + 1} & \Block[borders={right, tikz={dashed}}]{3-3}{\vec y} & & & & & & & & \\
        {\Vdots} & & & & & & & & & \\
        {n} & & & & & & & & & \\
    \end{pNiceArray}
$$

\end{document}

The main problem of my solution is that left exterior column is right aligned. According nicematrix documentation this is by design (page 24 on pdf documentation). In footnote 35 on this page I read that we need to use \CodeAfter and \Submatrix to make left exterior column be centering or to have other alignment. I tried this without success. The error is about the last column is empty, and I have no idea how to solve this. Of course there is an email of package author on the top of nicematrix documentation...

AGSH

[FPantigny]

Here is a solution with nicematrix and the first column left-aligned (by using the command \SubMatrix in the so-called \CodeAfter.

Code: Select all

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

\begin{document}

\[
    \begin{NiceArray}{lccccccccc}[first-row]
        & n + 1 & \cdots & n + m & 1 & \cdots & m & m +1 & \cdots & n \\
        n + 1& \Block[borders={bottom, right, tikz=dashed}]{3-3}{\vec{a}} & & &
               \Block[borders={bottom, right, tikz=dashed}]{3-3}{\vec{b}} & & &
               \Block[borders={bottom, tikz=dashed}]{3-3}{\vec{c}} & & \\
        \vdots & & & & & & & & & \\
        n + m & & & & & & & & & \\
        1 & \Block[borders={bottom, right, tikz=dashed}]{3-3}{\vec{x}} & & & \Block{6-6}{\vec{a}} & & & & & \\
        \vdots & & & & & & & & & \\
        m & & & & & & & & & \\
        m + 1 & \Block[borders={right, tikz=dashed}]{3-3}{\vec{y}} & & & & & & & & \\
        \vdots & & & & & & & & & \\
        n & & & & & & & & & \\
    \CodeAfter
        \SubMatrix({1-2}{9-10})
    \end{NiceArray}
\]

\end{document}