Here's a possible solution in which I assumed that the sections corresponding to appendices will be the last sections of their corresponding chapter. I defined an \appsection
command to change \thesection
so as to obtain the required formatting; this command has to be issued before the appendices for a chapter. Using the etoolbox
package, \chapter
restores the original meaning of \thesection
.
\documentclass{report}
\usepackage{etoolbox}
\pretocmd{\chapter}{\renewcommand\thesection{\thechapter.\arabic{section}}}{}{}
\newcommand\appsection{%
\setcounter{section}{0}%
\renewcommand\thesection{\thechapter.\Alph{section}}}
\begin{document}
\tableofcontents
\chapter{Test Chapter One}
\section{A regular section in chapter one}
\chapter{Test Chapter Two}
\section{A regular section in chapter two}
\appsection
\section{Derivation of MMSE Equation}
\subsection{Some remarks}
\subsection{Preliminary results}
\section{Proof of the main result}
\subsection{Some important consequences}
\chapter{Test Chapter Three}
\section{A regular section in chapter three}
\appsection
\section{Derivation of ABCD Equation}
\subsection{Preliminary results}
\section{Proof of the main result}
\subsection{Some important consequences}
\subsection{Some remarks}
\end{document}

In case hyperref is loaded, the above code has to be slightly changed to
\pretocmd{\chapter}{%
\renewcommand\thesection{\thechapter.\arabic{section}}%
\renewcommand\theHsection{\thechapter.\arabic{section}}}{}{}
\newcommand\appsection{%
\setcounter{section}{0}%
\renewcommand\thesection{\thechapter.\Alph{section}}%
\renewcommand\theHsection{\thechapter.\Alph{section}}}
\section
and show up in the ToC formatted as such? – Werner Sep 21 '12 at 15:39