# [Tex/LaTex] ‘Undefined control sequence’ error when typesetting table

errorstables

The error is

Undefined control sequence.

Here is the code:

\begin{table}[htb!!]
\center
\begin{tabular}{|c|c|c|c|c|c|}
\hline
\multicolumn{2}{|c|}{Experiment} & Initial tip deflection & frequency $\omega$ & base acceleration $a_b$ & Magnet gap $\delta$ \\
\hline
TC 1 &
\begin{tabular}{c}a \\ b\end{tabular} & \begin{tabular}{c} $10^{-3}\ mm$ \\ $5\ mm$\end{tabular} & Uniform $\in [9,14]\ Hz$ & $1\ m/s^2$ & $50\ mm$ \\
\hline
TC 2 &
\begin{tabular}{c}a \\ b\end{tabular} & \begin{tabular}{c} $10^{-3}\ mm$ \\ $5\ mm$\end{tabular} & $11.5 \ Hz$ & Uniform $\in \left[ 0.5,1.5 \right]\ m\s^2$ & $50\ mm$\\
\hline
TC 3 &
\begin{tabular}{c}a \\ b\end{tabular} & \begin{tabular}{c} $10^{-3}\ mm$ \\ $5\ mm$\end{tabular} & $11.5\ Hz$ & $1\ m/s^2$ & Uniform $\in [45,55]\ mm$\\
\hline
\multicolumn{2}{|c|}{TC 4} & Uniform $\in [0,5]\ mm$ & Uniform $\in [9,14]\ Hz$ & Uniform $\in [0.5,1.5]\ m/s^2$ & Uniform $\in [45,55]\ mm$ \\
\hline
\end{tabular}
\caption{Uncertain parameters/initial conditions }\label{table_exp}
\end{table}


! Undefined control sequence.

You have \s instead of /s