Math & Science ⇒ Enumerating equations

[guyafe]

Hi all
I have a simple question regarding Latex.
I tried many manuals but couldn't find the answer.
I am trying to write a document containing several sections, and in each there are equations.
I would like to number the equations with the number of sections, followed by a dot and then the equation number (e.g. 1.1, 1.2, 1.3, ..., 2.1, 2.2 etc.)
The thing is that I can't do it - I always get the equations numbered from 1 to the number of equations (1, 2, 3) regardless which section they are.

Can someone tell me what am I doing wrong?

Thanks

[localghost]

Especially as a new member please get used to posting always a full example (see Board Rules). This is essential and in your own interest if you expect to get help quickly [1].

From your description I assume that you are using the article class (or a similar one). You are nothing doing wrong. This is the way this class numbers equations. The amsmath package helps you to get your equations numbered as desired.

Code: Select all

\documentclass[11pt,a4paper,english]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{amsmath}

\numberwithin{equation}{section}

\begin{document}
  \section{Foo}
    \begin{equation}\label{eqn:einstein}
      E=mc^2
    \end{equation}

  \section{Bar}
    \begin{subequations}\label{eqn:binomi}
      \begin{align}
        (a+b)^2&=a^2+2ab+b^2 \label{subeqn-1:binomi} \\
        (a-b)^2&=a^2-2ab+b^2 \label{subeqn-2:binomi} \\
        (a+b)(a-b)&=a^2-b^2 \label{subeqn-3:binomi}
      \end{align}
    \end{subequations}
\end{document}

[1] View topic: Avoidable mistakes


Best regards and welcome to the board
Thorsten

[guyafe]

Great Thanks!

Thats just what was missing:
The \numberwithin command

Thanks again

Guy