As we all know, there are many equation environments to choose, including

• equation
• multline
• align
• eqnarray
• IEEEeqnarray

I prefer

•  for inline equation
• equation for single-line equation
• IEEEeqnarray for multi-line equation and equations

To use IEEEeqnarray, you should install IEEEtran, which can be downloaded at http://mirror.ctan.org/macros/latex/contrib/IEEEtran.zip

On Arch Linux, using texlive, I just use texconfig -> CONF to find the path of TEXMFLOCAL, and make a folder TEXMFLOCAL/tex/latex/IEEE and copy all the files in that folder. Finally, run texhash.

You should add this line in the preamble of your LaTeX file

\usepackage[retainorgcmds]{IEEEtrantools}


\begin{IEEEeqnarray}{rCl}