I have code for wherein I tried to insert the title for each column but I am getting an error. The error says:
Missing control sequence inserted
How to overcome this?
\documentclass[twocolumn,10pt]{article}%{asme2ej}
\usepackage{graphicx}
\usepackage{stfloats}
\usepackage{adjustbox}
\usepackage{scalerel}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{mathtools}
\usepackage{cuted}
\usepackage[Symbol]{upgreek}
\usepackage{epstopdf}
%\usepackage{float}
\usepackage{siunitx}
%\usepackage{caption}
\usepackage{enumitem}
\usepackage{caption}
\usepackage{subcaption}
\captionsetup{compatibility=false}
\usepackage{multirow, tabularx}
\usepackage{tikz}
\usepackage{pifont}
\usepackage{setspace}
\usepackage{multicol}
\usepackage{lipsum}
\begin{document}
\lipsum[1]
\begin{figure}[htb]
\centering
\includegraphics[width=\columnwidth]{example-image}
\caption{}
\label{fig:Transition_curves_spring}
\end{figure}
\lipsum[1]
\begin{figure}[htb]
\centering
\includegraphics[width=\columnwidth]{example-image}
\caption{}
\label{fig: Transition_curves_spring}
\end{figure}
\lipsum[12]
\begin{figure}[!htb]
\setkeys{Gin}{width=\linewidth, height=0.25\textheight}
\begin{subfigure}{\columnwidth}
\includegraphics{example-image}
\caption{Cantilever}
\label{fig:mode_1_max_beta}
\end{subfigure}
\begin{subfigure}{\columnwidth}
\includegraphics{example-image}
\caption{Simple Support}
\label{fig:mode_2_max_beta}
\end{subfigure}
\begin{subfigure}{\columnwidth}
\includegraphics{example-image}
\caption{Clamped-Clamped }
\label{fig:mode_3_max_beta}
\end{subfigure}
\caption{xxxxx}
\label{fig:location of max beta}
\end{figure}
\lipsum[2]
\begin{table}[tb]
\caption{}
\label{table:three spring beam}
\setlength\tabcolsep{0pt}
\begin{tabular*}{\linewidth}{@{\extracolsep{\fill}}
*{3}{S[table-format=4.0]}
S[table-format=1.4]
S[table-format=1.5]
S[table-format=1.3]
S[table-format=1.4]
}
\hline
\multicolumn{3}{c}{\begin{tabular}[c]{@{}c@{}}Non-dimensional\\ Stiffness\end{tabular}} & \multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Mode 1\\ $\beta_{1}$\end{tabular}} & \multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Mode 2\\ $\beta_{2}$\end{tabular}}\\ \hline
$K_{t}$ & $M$ & $K_{r}$ & \begin{tabular}[c]{@{}c@{}}Present\\ Method\end{tabular} & FEM & \begin{tabular}[c]{@{}c@{}}Present\\ Method\end{tabular} & FEM \\ \hline
0 & 0 & 0 & 3.142 & 3.140 & 6.281 & 6.2739 \\
50 & 0 & 0 & 3.458 & 3.461 & 6.382 & 6.374 \\
0 & 100 & 0 & 0.829 & 0.830 & 6.281 & 6.273 \\
0 & 0 & 200 & 4.118 & 4.136 & 6.281 & 6.273 \\
100 & 200 & 0 & 0.812 & 0.813 & 6.456 & 6.449 \\
300 & 0 & 400 & 4.741 & 4.757 & 6.883 & 6.875 \\
0 & 500 & 100 & 0.733 & 0.736 & 6.281 & 6.273 \\
$\infty$ & 0 & 1000 & 5.231 & 5.220 & 9.412 & 9.372 \\
$\infty$ & 100 & $\infty$ & 1.471 & 1.467 & 7.244 & 7.220 \\
300 & 800 & 1000 & 0.761 & 0.764 & 6.696 & 6.685 \\
1000 & 500 & 3000 & 0.918 & 0.922 & 7.007 & 6.990 \\
500 & 4000 & 800 & 0.525 & 0.527 & 6.837 & 6.824 \\
$\infty$ & $\infty$ & $\infty$ & 0.0046 & 0.00464 & 7.239 & 7.214 \\
\hline
\end{tabular*}
\medskip
\begin{tabular*}{\linewidth}{@{\extracolsep{\fill}}
*{3}{S[table-format=4.0]}
*{4}{S[table-format=2.3]}
}
\hline
\multicolumn{3}{c}{\begin{tabular}[c]{@{}c@{}}Non-dimensional\\ Stiffness\end{tabular}} & \multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Mode 1\\ $\beta_{1}$\end{tabular}} & \multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Mode 2\\ $\beta_{2}$\end{tabular}}\\ \hline
$K_{t}$ & $M$ & $K_{r}$ & \begin{tabular}[c]{@{}c@{}}Present\\ Method\end{tabular} & FEM & \begin{tabular}[c]{@{}c@{}}Present\\ Method\end{tabular} & FEM \\ \hline
0 & 0 & 0 & 9.403 & 9.393 & 12.298 & 12.492 \\
50 & 0 & 0 & 9.418 & 9.408 & 12.298 & 12.492 \\
0 & 100 & 0 & 7.857 & 7.830 & 12.273 & 12.492 \\
0 & 0 & 200 & 9.950 & 9.909 & 13.524 & 13.652 \\
100 & 200 & 0 & 7.968 & 7.943 & 12.273 & 12.492 \\
300 & 0 & 400 & 10.049 & 10.009 & 13.617 & 13.734 \\
0 & 500 & 100 & 7.950 & 7.918 & 13.075 & 13.064 \\
{$\infty$} & 0 & 1000 & 13.611 & 13.484 & 15.701 & 15.434 \\
{$\infty$} & 100 & {$\infty$} & 13.122 & 13.071 & 15.720 & 15.490 \\
300 & 800 & 1000 & 8.325 & 8.297 & 13.173 & 13.130 \\
1000 & 500 & 3000 & 9.196 & 9.173 & 13.189 & 13.144 \\
500 & 4000 & 800 & 8.583 & 8.557 & 13.172 & 13.130 \\
{$\infty$} & {$\infty$} & {$\infty$} & 13.123 & 13.024 & 15.799 & 15.490 \\
\hline
\end{tabular*}
\end{table}
\lipsum[12]
\begin{figure*}[b]
\setkeys{Gin}{width=\linewidth, height=0.25\textheight}
\begin{tabularx}{\linewidth}{*{2}{X}}
\includegraphics{example-image}
\caption{xxxxx}
\label{fig:mode shape with three springs}
&
\includegraphics{example-image}
\caption{xx}
\\
\includegraphics{example-image}
\caption{xxx}
\label{fig:Transition_curves_mass}
&
\includegraphics{example-image}
\caption{xx}
\label{fig:Linear-rotational spring}
\end{tabularx}
\end{figure*}
\lipsum[2-4]
\end{document}
siunitx'sStype columns and is text but not numbers in a set of{}(for example{$K_{t}$}instead of$K_{t}$). Apart from that, please note that your code is not a MWE as it contains a lot of code that is not needed to reproduce your problem. Also, where is the connection tolongtableas you've used this tag in your question but your code does not use thelongtablepackage? – leandriis Feb 12 at 14:39