# [texhax] Re: Equation Array Environment...

Martin Heller mr_heller at yahoo.dk
Thu Aug 4 18:12:29 CEST 2005

Chris Bourke wrote:
> I find the eqnarray/eqnarray* environments too restrictive--one can only
> have three columns formatted in {rcl}.  I've tried using the
> equationarray.sty file on ctan, but with no documentation, I don't find it
> useful, and it doesn't seem to do exactly what I want:
>
> I'd like an environment like the eqnarray/eqnarray* environment, but with
> 4 columns formatted in {rcll} in which the 4th column is always typeset in
> either textrm or mathrm font.  The use of this forth column is for
> explanations (i.e. "by Lemma x.x" or "By associativity", etc).
>
> Is there anything out there that can do this, or can a more experienced
> texer hack something together real quick?
>

Use one of the amsmath environments. Or if you really
mean that you want something like eqnarray, use a tabular.

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}

\begin{document}
\begin{align}
a+b&=c && \text{Text}\\
d+e&=f && \text{Some more text}
\end{align}

\begin{tabular}{>{$}r<{$}@{\;}c@{\;}>{$}l<{$}@{\hspace{2cm}}l}
a+b & = & c & Text \\
d+e & = & f & Some more text
\end{tabular}

\end{document}