[Tex/LaTex] Problems with labeling of Chapter 0

labels

I'm writing a final year project and I would like to start it with a "Preliminaries" chapter, whose number I'd like to be 0. I do the trivial \setcounter{chapter}{-1}, which makes the number of the chapter 0, but it also makes all formulae and all figures in the chapter be labeled as (1), (2), …, instead of (0.1), (0.2), … How can I fix this?

PS I am not sure which package governs the formulae/figures labeling. I use amsmath, if this matters.

\documentclass[oneside, a4paper, 11pt]{report}
\usepackage{amsmath}

\begin{document}

\setcounter{chapter}{-1}
\chapter{Preliminaries}

Text here...

\begin{equation}\label{eq}
    f = f(x)...
\end{equation}

I would like the label to be (0.1) instead of \eqref{eq}.

\chapter{Next chapter}

Compare the labels:

\begin{equation}
    g = g (x)...
\end{equation}

\end{document}

Output

Best Answer

Add the following line in your preamble:

\renewcommand{\theequation}{\thechapter.\arabic{equation}}

MWE:

\documentclass[oneside, a4paper, 11pt]{report}
\usepackage{amsmath}

\renewcommand{\theequation}{\thechapter.\arabic{equation}}

\begin{document}

\setcounter{chapter}{-1}
\chapter{Preliminaries}

Text here...

\begin{equation}\label{eq}
    f = f(x)...
\end{equation}

I would like the label to be (0.1) instead of \eqref{eq}.

\chapter{Next chapter}

Compare the labels:

\begin{equation}
    g = g (x)...
\end{equation}

\end{document}

enter image description here

The original definition in report.cls is

\renewcommand\theequation
  {\ifnum \c@chapter>\z@ \thechapter.\fi \@arabic\c@equation}

which means that the chapter number is printed only when greater than zero.

Related Solutions

[Tex/LaTex] Labeling problems with exam class usage when using multiple chapters

Looking at the source exam class would need quite a few changes to use repeated numbers as it uses the number counter internally in several places. However to help anyone else answering and to address other problems in the posted document here is a start at a solution.

You shouldn't use star form for numbered sections, and \numberwith should only be used once. the fact that it wasn't having an effect and you had to manually reset the question counter is related to your use of the * form. Nested counters reset when the parent counter is incremented with \stepcounter (or better \refstepcounter) setting the section counter via \setcounter does not do this (and also means you can not use \label and \ref to refer to the section.

update Perhaps the easiest way to restart the equation numbering without breaking the rest of the features is to maintain the counter with unique numbers eg 101, 1002, in the first section and 201, 202 in the second, and then just arrange that this gets printed as 1.1,1.2,2.1,2.1 in the heading:

enter image description here

\documentclass{exam}
\usepackage{amsmath}

\makeatletter

\def\@seccntformat#1{%
  \expandafter\ifx\csname the#1\endcsname\thesection Chapter~\fi
  \csname the#1\endcsname
  \setcounter{question}{\thesection00}%
   \quad}

\renewcommand\thequestion{%
\the\numexpr(\value{question}-49)/100\relax.%
\the\numexpr\value{question}-(100*((\value{question}-49)/100))\relax}

\makeatother

\begin{document}

    \begin{questions}
\fullwidth{\section{}}
        \question aaa

            \begin{solution}
xxx
            \end{solution}


\fullwidth{\section{}}

        \question bbb

            \begin{solution}
yyy
            \end{solution}
    \end{questions}

\end{document}

[Tex/LaTex] Labeling subcaption

Since counters are reset to zero, you can't use \refstepcounter to set up the \label. OTOH, you need \refstepcounter for cleverref and hyperref. So I generate the label before \refstepcounter then reset \@currentlabel after.

I see that \subcaption defines skip=6pt, but I can't figure out where skip is used. Also, \caption somehow knows whether it is at the top or bottom. I had to set up \mycaption for bottom only.

\documentclass{article}

\usepackage{graphicx}
\usepackage{caption}
\usepackage{hyperref}

\newcounter{subfig}[figure]

\makeatletter
\newcommand{\mycaption}{\edef\@templabel{Text \thesubfig}%
  \refstepcounter{subfig}%
  \let\@currentlabel=\@templabel% \global?
  \vspace{6pt}%
  \makebox[\textwidth]{\@currentlabel}}
\makeatother

\newcommand{\topanchor}[1]% #1 = counter
  {\refstepcounter{#1}\addtocounter{#1}{-1}\par}

\begin{document}

\section{Section}
\begin{center}
\topanchor{figure}%
\begin{minipage}{0.4\textwidth}
\topanchor{subfig}%
\includegraphics[width=\textwidth]{example-image-a.pdf}
\mycaption
\end{minipage}
\begin{minipage}{0.4\textwidth}
\topanchor{subfig}%
\includegraphics[width=\textwidth]{example-image-b.pdf}
\mycaption\label{here}
\end{minipage}
\captionof{figure}{Description}\label{there}
\end{center}

Look at \ref{here}.

Hyperlink test \ref{there}.
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Labeling problems with exam class usage when using multiple chapters

[Tex/LaTex] Labeling subcaption

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