centering figure

I want to put this figure (Matrix) at the center but I can't, even though the title is centered:

I have this code :

\begin{center}
\begin{figure}[H]
\begin{center}
$\begin{blockarray}{cccccc} 123 & 12,3 & 13,2 & 1,23 & 1,2,3\\ \begin{block}{(ccccc)c} 0 & 1 & 1 & 1 & 0 & 123 \\ 1 & 0 & 0 & 0 & 1 & 12,3 \\ 1 & 0 & 0 & 0 & 1 & 13,2 \\ 1 & 0 & 0 & 0 & 1 & 1,23 \\ 0 & 1 & 1 & 1 & 0 & 1,2,3 \\ \end{block} \end{blockarray}$
\end{center}

\caption{ Matrice d'adjacence de treillis de 5 partitions de $E = \{1,2,3\}$}
\end{figure}
\end{center}

• It seems that blockarray belongs to the blkarray package. – Karlo Mar 13 '19 at 20:58

You have too many center environments:
\begin{figure}
$\begin{blockarray}{cccccc} 123 & 12,3 & 13,2 & 1,23 & 1,2,3\\ \begin{block}{(ccccc)c} 0 & 1 & 1 & 1 & 0 & 123 \\ 1 & 0 & 0 & 0 & 1 & 12,3 \\ 1 & 0 & 0 & 0 & 1 & 13,2 \\ 1 & 0 & 0 & 0 & 1 & 1,23 \\ 0 & 1 & 1 & 1 & 0 & 1,2,3 \\ \end{block} \end{blockarray}$
\caption{Matrice d'adjacence de treillis de 5 partitions de $E = \{1,2,3\}$}

I've removed the [H] specification that I usually recommend not to use, particularly with big objects such as this.