# align multiple equations without amsmath package

I have to use iopart document class. One of major problems which I came across is aligning multiple equations. For example, for reach

\begin{align}
a & = b \label{eq1} \\
c & = d \label{eq2}
\end{align}


we must use either amsmath package or other ones. Unfortunately, iopart does not coincide with it. In this situation how can I align my equations that have gotten me to stack?

• Could you please provide a complete (compilable) minimal example? – CarLaTeX Jun 29 '19 at 7:27
• Then try with older format, \begin{eqnarray}...\end{eqnarray} – MadyYuvi Jun 29 '19 at 7:30

You can use \usepackage{IEEEtrantools} to align multiple equations without to use amsmath package.

\documentclass[a4paper,12pt]{article}
\usepackage{IEEEtrantools}
\begin{document}
\begin{IEEEeqnarray}{lCr}
a & = b \label{eq1} \\
c & = d \label{eq2}
\end{IEEEeqnarray}
\end{document}

• Can you help me to understand that the difference between general eqnarray and IEEEeqnarray? – MadyYuvi Jul 1 '19 at 7:11
• @MadyYuvi Hi. Your question is correct and I'll give you the correct explanations. If you go to pag. 8, you can read that The eqnarray-environment, however, has a few very severe disadvantages:; The spaces around the equality signs are too big. Particularly, they are not the same as in the multline-and equation-environments; The expression sometimes overlaps with the equation number even though there would be enough room on the left, etc.I suggest the tutorial guide. – Sebastiano Jul 1 '19 at 19:24
• Thanks a lot... – MadyYuvi Jul 2 '19 at 4:29

You can use the package witharrows which provides an environment DispWithArrows which has by default exactly the same behaviour as the environment align of amsmath.

\documentclass{iopart}
\usepackage{witharrows}
\begin{document}
\begin{DispWithArrows}
a & = b \label{eq1} \\
c & = d \label{eq2}
\end{DispWithArrows}
\end{document}


With DispWithArrows, you have the ability to add arrows on the right for explanations (hence the name):

\documentclass{iopart}
\usepackage{witharrows}
\begin{document}
\begin{DispWithArrows}
a & = b \Arrow{explanation} \label{eq1} \\
c & = d \label{eq2}
\end{DispWithArrows}
\end{document}


With mathenv (good old) package which significantly improve eqnarray environment (package is based on mdwtab's table handling macros).

\documentclass[a4paper,12pt]{article}
\usepackage{mathenv}

\begin{document}
\begin{eqnarray}[rl]
a   & = b \label{eq1} \\
c   & = d \label{eq2}
\end{eqnarray}
\end{document}


• My compliments for using an old but efficient package :-) – Sebastiano Jul 3 '19 at 21:38