# Problems with overriding the values in a cls file

I'm writing a thesis and I'm trying to make the Table of Contents single spaced. This question was asked before and I tried the following solution in my .tex file:

\begin{singlespace}
\tableofcontents
\end{singlespace}


but it didn't work (everything compiles fine but the Table of Contents is still double spaced). I looked into the .cls file I'm using - iitthesis.cls - which prefer not to change; I found this:

% \ssp : single-spacing
% \dsp : double-spacing
% \tsp : triple-spacing
\renewcommand{\normalsize}{\@normalsize}
\def\ssp{\def\baselinestretch{1.0}\large\normalsize}
\def\dsp{\def\baselinestretch{1.66}\large\normalsize}
\def\tsp{\def\baselinestretch{2.6}\large\normalsize}
...
\def\tableofcontents{
\begin{center}
\end{center}
\ssp
\hfill Page\@starttoc{toc}}


So, is it the case that \dsp{TABLE OF CONTENTS\\} is overriding \begin{singlespace}? And if yes, how do I solve this? Should I define \tableofcontents in my .tex file as a new command that will override the one in the .cls file?

-
Thanks Jon for you answer. I did what you suggested and found out that it's not even the dsp line. It's actually the \ssp line that determines that space, which means the table of contents should be single-spaced using this class. However, I see it as double-spaced, and when I change \ssp to \dsp it gets even worse, so now I need to figure out why single-space looks like double-space... –  user247866 Sep 27 '12 at 3:34
@jon Here it is: iit.edu/graduate_college/academic_affairs/pdfs/iitthesis –  user247866 Sep 27 '12 at 3:51

I think the problem resides in the definition of \Chapter. (The 'double spacing' is by design.) It seems like a very strange .cls file, and I'm not certain about the precise nature of the problem you are having, but the following might be the fix you are looking for:

\renewcommand{\Chapter}[1]{%
\clearpage
\noindent
\refstepcounter{chapter}
\begin{center}
\dsp{CHAPTER\space\thechapter\\}
\vspace{10pt}
\ssp\uppercase{#1}
\vspace{-5pt}
\end{center}
}