How to create a table like the following picture? I read latex table styles post in here. But I don' t find.
begin{tabular}{||c|c|c|c|c|c|c|}
\hline \hline$x$ & $t$ & Exact solution $u(x, t)$ & $u_{4}(x, t)$ & HPM and DTM $u_{4}(x, t)$ & Abssolute error $u_{4}(x, t)$ & Abssolute error HPM and DTM $u_{4}(x, t)[17,18]$ \\
\hline 0.25 & 0.25 & $3.2101 \cdot 10^{-1}$ & $3.2101 \cdot 10^{-1}$ & $3.21004 \cdot 10^{-1}$ & $5.7849 \cdot 10^{-7}$ & $2.1224 \cdot 10^{-6}$ \\
\hline 0.25 & 0.5 & $4.1218 \cdot 10^{-1}$ & $4.1216 \cdot 10^{-1}$ & $4.12109 \cdot 10^{-1}$ & $2.00 \cdot 10^{-5}$ & $7.09427 \cdot 10^{-5}$ \\
\hline 0.25 & 0.75 & $5.2925 \cdot 10^{-1}$ & $5.2909 \cdot 10^{-1}$ & $5.28687 \cdot 10^{-1}$ & $1.6439 \cdot 10^{-4}$ & $5.63481 \cdot 10^{-4}$ \\
\hline 0.25 & $1 .$ & $6.7957 \cdot 10^{-1}$ & $6.7882 \cdot 10^{-1}$ & $6.77083 \cdot 10^{-1}$ & $7.5129 \cdot 10^{-4}$ & $2.48712 \cdot 10^{-3}$ \\
\hline 0.5 & 0.25 & $6.4201 \cdot 10^{-1}$ & $6.4201 \cdot 10^{-1}$ & $6.42008 \cdot 10^{-1}$ & $1.157 \cdot 10^{-6}$ & $4.2448 \cdot 10^{-6}$ \\
\hline 0.5 & 0.5 & $8.2436 \cdot 10^{-1}$ & $8.2432 \cdot 10^{-1}$ & $8.24219 \cdot 10^{-1}$ & $4.00 \cdot 10^{-5}$ & $1.41885 \cdot 10^{-4}$ \\
\hline 0.5 & 0.75 & 1.0585 & 1.0582 & 1.05737 & $3.2879 \cdot 10^{-4}$ & $1.12696 \cdot 10^{-3}$ \\
\hline 0.5 & $1 .$ & 1.3591 & 1.3576 & 1.35417 & $1.5026 \cdot 10^{-3}$ & $4.97425 \cdot 10^{-3}$ \\
\hline 0.75 & 0.25 & $9.6302 \cdot 10^{-1}$ & $9.6302 \cdot 10^{-1}$ & $9.63013 \cdot 10^{-1}$ & $1.7355 \cdot 10^{-6}$ & $6.3672 \cdot 10^{-6}$ \\
\hline 0.75 & 0.5 & 1.2365 & 1.2365 & 1.23633 & $6.00 \cdot 10^{-5}$ & $2.12828 \cdot 10^{-4}$ \\
\hline 0.75 & 0.75 & 1.5878 & 1.5873 & 1.58606 & $4.9318 \cdot 10^{-4}$ & $1.69044 \cdot 10^{-3}$ \\
\hline 0.75 & $1 .$ & 2.0387 & 2.0365 & 2.03125 & $2.2539 \cdot 10^{-3}$ & $7.46137 \cdot 10^{-3}$ \\
\hline $1 .$ & 0.25 & 1.284 & 1.284 & 1.28402 & $2.314 \cdot 10^{-6}$ & $8.4896 \cdot 10^{-6}$ \\
\hline $1 .$ & 0.5 & 1.6487 & 1.6486 & 1.64844 & $8.00 \cdot 10^{-5}$ & $2.83771 \cdot 10^{-4}$ \\
\hline $1 .$ & 0.75 & 2.117 & 2.1163 & 2.11475 & $6.5758 \cdot 10^{-4}$ & $2.25392 \cdot 10^{-3}$ \\
\hline $1 .$ & $1 .$ & 2.7183 & 2.7153 & 2.70833 & $3.0052 \cdot 10^{-3}$ & $9.9485 \cdot 10^{-3}$ \\
\hline
\end{tabular}
\usepackage{hhline}
and ` \hhline{|t:==:t:==:t:==:t|}`... – MadyYuvi May 30 '20 at 6:07