Using the \hhline
command i found some imperfection in the double line. How can i fix it?
Imperfection
Table
\documentclass[11pt]{amsart}
\usepackage{amssymb}
\usepackage{hhline}
\usepackage{siunitx}
\sisetup{output-decimal-marker={.}, group-separator={\,}}
\usepackage{eurosym}
\usepackage{dcolumn}
\usepackage{multirow}
\begin{document}
\begin{table}[htbp]
\begin{center}
\begin{tabular}{|lr|lr l|} \hline
H & 5 & $W_N$ & 250 & \si{\gram} \\
L & 26 & $W_L$ & 241 & \si{\gram} \\
P & \num{3000} & $C_u$ & 3E{-4} & \euro/\si{\gram} \\
$n_C$ & \num{142506} & $c_0$ & 2E-01 & \euro/pack \\
$\delta$& 1 & $c_1$ & 5E-01 & \euro/h \\
\hhline{=====}
& \multicolumn{2}{c}{$r.s_{std}$} & \multicolumn{2}{c|}{$r.s_{iter}$} \\
\hhline{=====}
Media(W) & \multicolumn{2}{D{.}{.}{3.4}}{245.9463} & \multicolumn{2}{D{.}{.}{3.4}|}{245.9459}\\
DevStd(W) & \multicolumn{2}{D{.}{.}{3.4}}{3.9932} & \multicolumn{2}{D{.}{.}{3.4}|}{3.9939}\\
\emph{f.o} & \multicolumn{2}{D{.}{.}{3.4}}{0.27395} & \multicolumn{2}{D{.}{.}{3.4}|}{0.27395}\\
$n_B$ & \multicolumn{2}{D{.}{.}{3.4}}{3000} & \multicolumn{2}{D{.}{.}{3.4}|}{3000}\\
$t_{tot}$ & \multicolumn{2}{D{.}{.}{3.4}}{2612.22} & \multicolumn{2}{D{.}{.}{3.4}|}{6906.10}\\
\hhline{=====}
Config. & \multicolumn{2}{c}{10 20 40 50 200} & \multicolumn{2}{c|}{40 130 130 220 220}\\ \hline
\end{tabular}
\begin{footnotesize}
\caption{Confronto $r.s_{std}$ Vs $r.s_{iter}$ [$C_u > 0$]}
\label{tab:Confronto_rs_C_mag_0}
\end{footnotesize}
\end{center}
\end{table}
\end{document}
r.s_{std}
refers to the column underneath it? Well, with that table format they won't understand. In Italian one says “Confronto tra A e B”, not “Confronto A Vs B”. If you prefer to use Itanglish, at least write “vs” (lowercase).