I want the equation number to be shown only at the last line, or better, somewhere in the middle of all. So instead of (1), (2), ... only (1).
I use \begin{align} ... \end{align}
[Tex/LaTex] Show equation number only once in align environment
alignequations
Related Solutions
Use \tag:
\documentclass{article}
\usepackage{amsmath}
\newcommand\numberthis{\addtocounter{equation}{1}\tag{\theequation}}
\begin{document}
\begin{align*}
a &=b \\
&=c \numberthis \label{eqn}
\end{align*}
Equation \eqref{eqn} shows that $a=c$.
\begin{equation}
d = e
\end{equation}
\end{document}
See page 3 of the amsmath package documentation for details.
Don't use eqnarray ! It yields bad spacing. Replace it with one of the amsmath environments. Here you can use an aligned environment, with option [b], nested in equation:
\documentclass[11pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
\begin{aligned}[b]
\dot{\epsilon}&= u_\mu u_\nu\Bigl(\dot{I}^{\mu\nu}_{(0)+}+\dot{I}^{\mu\nu}_{(0)-}\Bigr)\\
&= u_\mu u_\nu\int\mathrm{dp}~p^\mu p^\nu\bigl(\dot{f}_{(0)}+\dot{\bar{f}}_{(0)})
\end{aligned}
\label{eq:1}
\end{equation}
\end{document}
Best Answer
You can use the
splitenvironment from theamsmathpackage: