# I'm getting the error “Undefined control sequence”?

I am getting the error "undefined control sequence" on running the MWE given below. Please help me sort it out....

     \documentclass[journal,12pt,draftclsnofoot,onecolumn]{IEEEtran}
\usepackage{amsmath}
\usepackage{cite}
\usepackage{multirow}
\usepackage{multicol}
\begin{document}
\begin{table}[h!]
\centering
\caption{Optimized Parameter Values}
\renewcommand{\arraystretch}{1}
\scalebox{1}
{
\begin{tabular}
{|p{2.5cm}|p{1.5cm}|p{1cm}|p{1cm}|p{2cm}|p{1.5cm}|p{1.5cm}|}
\multicolumn{7}{}{} \\ \hline
Type of Controller & Parameter & Xmax & Xmin & Iter. reqd. for
convergence & Optimized value & $Wmin$ \\ \hline
\multirow{6}{*}{PSO-SOSMC} & $c_1$ & 5 & 0.1 & 37 & 4.75& 68.43 \\
\cline{2-7}
& $c_2$ & 5 & 0.1 & 10 & 4.273& 20.45 \\ \cline{2-7}
& $\lambda_1$& 5 & 0.1 & 37 & 2.75 & 68.43\\ \cline{2-7}
& $\lambda_2$& 5 & 0.1 & 10 & 3.59 & 20.45\\ \cline{2-7}
& $W_1$& 1 & 0.05 & 37 & 0.43 & 68.45\\ \cline{2-7}
& $W_2$& 1 & 0.05 & 10 & 0.218 & 20.43\\ \hline
\multirow{4}{*}{PSO-BELBIC} & $W_1$ & 5 & 0.1 & 36 & 4.5 &
27.34 \\ \cline{2-7}
& $W_2$ & 5 & 0.1 & 14 & 4.5 & 61.63 \\ \cline{2-7}
& $G_1$ & 5 & 0.1 & 36 & 1.4 & 27.34 \\ \cline{2-7}
& $G_2$ & 5 & 0.1 & 14 & 1.4 & 61.63\\ \hline
\end{tabular}
}
\label{optimized_values}
\end{table}
\end{document}

• Welcome to TeX.SX! \usepackage{graphicx} is missing (apart from the final \end{document}). – gernot Oct 9 '16 at 10:57
• you need graphicx for \scalebox but what is the point of \scalebox{1} ? It just makes tex do a lot of work to multiply the size of everything by 1 ??? also if you do use scalebox do not have space after the { and before the } as you have it or you get unwanted white space in the output. – David Carlisle Oct 9 '16 at 11:00
• I bet your paper is due within the next tenty minutes. I don't see another reason for crossposting – Johannes_B Oct 9 '16 at 11:01

scalebox is defined by package graphicx, but you don't even need it. I would suppose a different approach to tables, though. Keep it simple.

\documentclass[journal,12pt,draftclsnofoot,onecolumn]{IEEEtran}
\usepackage{amsmath}
\usepackage{cite}
%\usepackage{graphicx}  %unneeded
\usepackage{multirow}  %unneeded
%\usepackage{multicol}  %unneeded
\usepackage{showframe}
\usepackage{booktabs}
\begin{document}
\begin{table}%[h!]
\centering
\caption{Optimized Parameter Values}
\begin{tabular}{llllp{7em}p{7em}l}
\toprule
Type of Controller & Parameter    & Xmax & Xmin & \raggedright Iter. reqd. for convergence & Optimized value & $W_\mathrm{min}$ \\ \midrule
PSO-SOSMC        & $c_1$        & 5    & 0.1  & 37                                       & 4.75            & 68.43 \\
& $c_2$        & 5    & 0.1  & 10                                       & 4.273           & 20.45 \\
& $\lambda_1$ & 5    & 0.1  & 37                                       & 2.75            & 68.43\\
& $\lambda_2$ & 5    & 0.1  & 10                                       & 3.59            & 20.45\\
& $W_1$       & 1    & 0.05 & 37                                       & 0.43            & 68.45\\
& $W_2$       & 1    & 0.05 & 10                                       & 0.218           & 20.43\\ \cmidrule(lr){2-7}
PSO-BELBIC       & $W_1$        & 5    & 0.1  & 36                                       & 4.5             & 27.34 \\
& $W_2$        & 5    & 0.1  & 14                                       & 4.5             & 61.63 \\
& $G_1$        & 5    & 0.1  & 36                                       & 1.4             & 27.34 \\
& $G_2$        & 5    & 0.1  & 14                                       & 1.4             & 61.63\\ \bottomrule
\end{tabular}

\vspace{2cm}
%   \scalebox{1}
%   {
\begin{tabular}{|p{2.5cm}|p{1.5cm}|p{1cm}|p{1cm}|p{2cm}|p{1.5cm}|p{1.5cm}|}
\multicolumn{7}{}{} \\ \hline
Type of Controller & Parameter & Xmax & Xmin & Iter. reqd. for convergence & Optimized value & $Wmin$ \\ \hline
\multirow{6}{*}{PSO-SOSMC} & $c_1$ & 5 & 0.1 & 37 & 4.75& 68.43 \\ \cline{2-7}
& $c_2$ & 5 & 0.1 & 10 & 4.273& 20.45 \\ \cline{2-7}
& $\lambda_1$& 5 & 0.1 & 37 & 2.75 & 68.43\\ \cline{2-7}
& $\lambda_2$& 5 & 0.1 & 10 & 3.59 & 20.45\\ \cline{2-7}
& $W_1$& 1 & 0.05 & 37 & 0.43 & 68.45\\ \cline{2-7}
& $W_2$& 1 & 0.05 & 10 & 0.218 & 20.43\\ \hline
\multirow{4}{*}{PSO-BELBIC} & $W_1$ & 5 & 0.1 & 36 & 4.5 & 27.34 \\ \cline{2-7}
& $W_2$ & 5 & 0.1 & 14 & 4.5 & 61.63 \\ \cline{2-7}
& $G_1$ & 5 & 0.1 & 36 & 1.4 & 27.34 \\ \cline{2-7}
& $G_2$ & 5 & 0.1 & 14 & 1.4 & 61.63\\ \hline
\end{tabular}
%   }
\label{optimized_values}
\end{table}
\end{document}

• Thank You, David , Gernot and Johannes :). It worked out well. Sorry for the crossposting in the latex community, I thought the two communities are decoupled and I hadn't expected such prompt response. – biswajit Oct 9 '16 at 11:13
• Johannes, your tabular representation is very elegant....Thank you once again :) – biswajit Oct 9 '16 at 11:27

Johannes, I have failed to mention earlier that I need the scalebox and arraystretch commands to resize my table according to the need of the paper. I have tweaked your code to include those two commands and it looks just fine. The code is shown below

    \documentclass[journal,12pt,draftclsnofoot,onecolumn]{IEEEtran}
\usepackage{amsmath}
\usepackage{cite}
\usepackage{graphicx}  %unneeded
\usepackage{booktabs}
\begin{document}
\begin{table}%[h!]
\centering
\renewcommand{\arraystretch}{1.3}
\caption{Optimized Parameter Values}
\scalebox{0.8}
{
\begin{tabular}{llllp{7em}p{7em}l}
\toprule
Type of Controller & Parameter    & Xmax & Xmin & \raggedright Iter. reqd. for convergence & Optimized value & $W_\mathrm{min}$ \\ \midrule
PSO-SOSMC        & $c_1$        & 5    & 0.1  & 37                                       & 4.75            & 68.43 \\
& $c_2$        & 5    & 0.1  & 10                                       & 4.273           & 20.45 \\
& $\lambda_1$ & 5    & 0.1  & 37                                       & 2.75            & 68.43\\
& $\lambda_2$ & 5    & 0.1  & 10                                       & 3.59            & 20.45\\
& $W_1$       & 1    & 0.05 & 37                                       & 0.43            & 68.45\\
& $W_2$       & 1    & 0.05 & 10                                       & 0.218           & 20.43\\ \cmidrule(lr){2-7}
PSO-BELBIC       & $W_1$        & 5    & 0.1  & 36                                       & 4.5             & 27.34 \\
& $W_2$        & 5    & 0.1  & 14                                       & 4.5             & 61.63 \\
& $G_1$        & 5    & 0.1  & 36                                       & 1.4             & 27.34 \\
& $G_2$        & 5    & 0.1  & 14                                       & 1.4             & 61.63\\ \bottomrule
\end{tabular}
}
\label{optimized_values}
\end{table}
\end{document}

• Maybe you should remove the wrong %unneded now. ;-) And the space that David talked about before. – Johannes_B Oct 9 '16 at 12:09