Augmented matrix with labeled rows at the right

Question

I would like to write an augmented matrix with labeled rows out of the right bracket of the matrix, in such a way to enlight operations by row for Gaussian elimination procedure. I'm using this code for writing augmented matrices

Preamble:

\newenvironment{sysmatrix}[1]
{\left(\begin{array}{@{}#1@{}}}
{\end{array}\right)}

Result:

$$
  \begin{sysmatrix}{rrr|r}
   1 &  2 & 0 & 0 \\
  -1 &  1 & 2 & 0 \\
   1 &  0 & 1 & 5 \\
   0 & -2 & 1 & 4
   \end{sysmatrix}
$$

So now, how can I get labeled rows at the right? Have you some suggestions for sample codes?

Thank you

Answer 1

With {pNiceArray} of nicematrix.

\documentclass{article}
\usepackage{nicematrix}

\begin{document}

\newenvironment{sysmatrix}
{\begin{pNiceArray}[last-col]}
{\end{pNiceArray}}

\[\begin{sysmatrix}{rrr|r}
 1 &  2 & 0 & 0 & L_1 \\
-1 &  1 & 2 & 0 & L_2 \\
 1 &  0 & 1 & 5 & L_3 \\
 0 & -2 & 1 & 4
\end{sysmatrix}\]

\end{document}

You need several compilations.

Answer 2

I solved by creating a matrix with

\begin{matrix}
\end{matrix}

at the right of the main one, and putting operations by rows into its elements.

Thank you anyway.