Changing inline math symbols throughout a whole document

Question

I have a document at hand that was written by using an old template and now I want to copy it to a new one. However, when I do this and execute the code I am facing the error

Missing $ inserted.

for all inline math modes. That's because in my initial template I used the symbol \( \) to write all the inline math equations and somehow my new template does not accept this notation but forces me to use $ instead. So, my question is: What should I do to define the equality $...$ = \(...\) or how can I interchange these two?

Answer 1

Here's an attempt to clean things up a bit. More could be done, but I think this modifies the worst features of the original template.

\documentclass[12pt,letterpaper]{article}
\usepackage{mathtools,amssymb}
\usepackage{graphicx,xcolor}
\usepackage{verbatim}
\usepackage{fancybox}
\usepackage{ulem}
\usepackage{enumitem}
% \usepackage{subfigure}% obsolete! use subfig or, better, subcaption
\usepackage{bbm}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{textcomp}
\newlength\normalparindent
\setlength\normalparindent\parindent
\usepackage{parskip,setspace}
\setstretch{1.3}
\usepackage[textwidth = 6.5in, textheight = 8.5in, marginparwidth=0pt, marginparsep=0pt, headheight=0pt, headsep=0pt, left=1in, top=1.2in]{geometry}
\usepackage{titling}

\newcommand{\Comment}[1]{{}}
\definecolor{MyDarkBlue}{rgb}{0.15,0.15,0.45}
\usepackage[linktocpage=true]{hyperref}
\hypersetup{
  colorlinks=true,
  citecolor=MyDarkBlue,
  linkcolor=MyDarkBlue,
  urlcolor=MyDarkBlue,
  pdfauthor={John Smith},
  pdftitle={SUBJECT},
  pdfsubject={hep-th}
}

% use align rather than eqnarray
\newcommand{\nn}{\nonumber}

\newcommand{\gmu}{\gamma^\mu}
\newcommand{\gnu}{\gamma^\nu}
\newcommand{\glmu}{\gamma_\mu}
\newcommand{\gf}{\gamma^5}
\newcommand{\Tr}{\text{Tr}}
\newcommand{\qb}{\mathbf{q}}
\newcommand{\pb}{\mathbf{p}}
\newcommand{\kb}{\mathbf{k}}
\newcommand{\xb}{\mathbf{x}}
\newcommand{\pd}{(2\pi)^d}
\newcommand{\intx}{\int d^d \mathbf{x}\ }

\newcommand{\la}{\langle}
\newcommand{\ra}{\rangle}
\newcommand{\lb}{\left[}
\newcommand{\rb}{\right]}
\newcommand{\half}{\frac{1}{2}}
\newcommand{\pf}{(2\pi)^4}
\newcommand{\intkd}{\int \frac{d^Dk}{(2\pi)^D}\ }
\newcommand{\intpd}{\int \frac{d^Dp}{(2\pi)^D}\ }
\newcommand{\intpdo}{\int \frac{d^{D-1}k}{(2\pi)^{D-1}}\ }
\newcommand{\intl}{\int \frac{d^4l}{(2\pi)^4}\ }
\newcommand{\intld}{\int \frac{d^dl}{(2\pi)^d}\ }
\newcommand{\intle}{\int \frac{d^4l_E}{(2\pi)^4}\ }
\newcommand{\intp}{\int d^d \mathbf{p}\ }
\newcommand{\wsp}{\omega_{\mathbf{p}}}
\newcommand{\intpp}{\int \frac{d^d \mathbf{p}}{\sqrt{\pd 2\wsp}}\ }

\title{SUBJECT\thanks{This is a title.}}
\author{John Smith\textsuperscript{\itshape a,}\thanks{E-mail address: \Comment{\href{mail@mail.edu}}{\url{mail@mail.edu}}}}
\date{}
\pretitle{\begin{center}\LARGE\bfseries}% Note that your original settings do not get bold small-caps and would not do so even if this shape existed in bold for this font. If you want small-caps, change \bfseries to \scshape
\posttitle{\par\end{center}\vskip 10mm}
\preauthor{\begin{center}\large\scshape}
\postauthor{\par\end{center}\vskip 10mm}
\predate{}
\postdate{}
\renewcommand\maketitlehookc{\begin{center}\itshape\textsuperscript{a}Department,\par Address\par\end{center}\vskip 10mm}

\numberwithin{equation}{section}

\begin{document}
\setlength\parindent\normalparindent% Not at all clear this is wise with skip between paragraphs as well, but if you must, you must...
\maketitle\thispagestyle{empty}

\begin{abstract}
Abstract goes in here.
\end{abstract}
\clearpage

\tableofcontents
\clearpage

\section{Introduction}

\section{Conclusions}

\section{Acknowledgements}

\appendix

\section{Appendix 1}

\addcontentsline{toc}{section}{References}
\input{references.tex}

\end{document}