# How do I make a double \hline in the vertical direction

When you put two \hline in a latex table it separates it in two different blocks. I want to make that, but in the vertical direction I have tried putting in the tabular options{|c||cccc|} but this doesn't work beause horizontal lines cross the entire table without leaving a blanck between the first and second column.

My table is as follows.

\begin{table}[]
\centering
\begin{tabular}{|c||ccccccccc|}
\hline
r,s & 0&1& 2&3&4&5&6&7&8 \\ \hline \hline
0& 1&$\R\oplus \R$ & $\R(2)$ & $\C(2)$&$\H(2)$&$\H(2)\oplus\H(2)$&$\H(4)$&$\H(4)\oplus\H(4)$&$\R(16)$\\
\hline
\end{tabular}
\caption{Caption}
\label{tab:my_label}
\end{table}

• use || and then use \hhline from the package of that name if you don't want the hlines to cross. – David Carlisle Feb 8 '17 at 22:40
• Welcome to TeX SX! What are \R, \C, \H? – Bernard Feb 8 '17 at 22:43
• @Bernard, I'm almost sure that it means \mathbb{R} and so on... very popular new commands for math papers.... lol – Sigur Feb 8 '17 at 22:54
• \H is a very bad idea for that purpose because it is already defined, this could make bibliographies entertaining – Au101 Feb 8 '17 at 22:59
• @Au101 -- for some definition of "entertaining". (in a production environment, "exasperating" is more often closer to the epithet used, while striving to remain polite.) – barbara beeton Feb 9 '17 at 2:17

\documentclass{article}

\usepackage{hhline}

\begin{document}

\begin{table}
\centering
\begin{tabular}{|c||ccccccccc|}
\hhline{-||---------}
r,s & 0&1& 2&3&4&5&6&7&8 \\ \hhline{=::=========}
0& 1&$R\oplus R$ & $R(2)$ & $C(2)$&$H(2)$&
$H(2)\oplus H(2)$&$H(4)$&$H(4)\oplus H(4)$&$R(16)$\\
\hhline{-||---------}
\end{tabular}
\caption{Caption}
\label{tab:my_label}
\end{table}
\end{document}