Rename Equation with subsubsection

Question

I' like to rename the equations so:

chapter.section.subsection,subsubsection.theequation

I tried with

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

First Edit: I use frequently book and article classes.

But it doesn't function. Why?

Thank you

Answer 1

You can use amsmath's \numberwithin command to number equations within subsubsections.

In an article document, you can do as in the following example.

\documentclass{article}
\usepackage{amsmath}
\numberwithin{equation}{subsubsection}
\begin{document}
\section{A section}
\subsection{A subsection}
\subsubsection{A subsubsection}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\end{document}

In a book document, subsubsections are not numbered by default, so you can add \setcounter{secnumdepth}{3} to number them.

\documentclass{book}
\usepackage{amsmath}
\setcounter{secnumdepth}{3}
\numberwithin{equation}{subsubsection}
\begin{document}
\chapter{A chapter}
\section{A section}
\subsection{A subsection}
\subsubsection{A subsubsection}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\end{document}