Problems using widetext.sty

Question

I need to prepare a document for a journal and I'm using the twocolumn option in the article class. Now I have a horrible equation that makes use of the cases environment so it's hard to split up to make it fit into one column. I do not want to use the figure* environment because I have no control over where to put the equation.

What I want to do is to use the widetext package and make sure that this equation looks something like it would like when one uses revtex4. However, when compiling my document I get an error, namely "improper \prevdepth". Does anyone have a clue what I have to do here?

A minimum working example (using the actual formula)

\documentclass[twocolumn]{article}
\usepackage{widetext}
\usepackage{flushend}
\usepackage{cuted}

\begin{document}

a lot of text ...


Here
\begin{widetext}
\begin{eqnarray} \label{e27}
T_{nn''}^{mm''}=({-}1)^{p-p''}\,\dil_0^{\infty}\,J_{m-m''}(au)\,J_{n''}(bu)\,J_{n+1}(u)\,du~=
\begin{cases}
& \dfrac{(q{+}p'')!\,(p{-}p'')!}{(q{-}q'')!\,(p{+}q'')!}\,a^{m-m''}b^{n''}\,P_{p-p''}^{(m-m'',n'')}(1{-}2A^2)P_{p-p''}^{(m-m'',n'')}(2B^2{-}1)~~~ \\ & \text{when}~~~n-n''\geq m-m''\geq0~,\\
\\
& \dfrac{(p{+}q'')!\,(q{-}q'')!}{(p{-}p'')!\,(q{+}p'')!}\,a^{m''-m}b^{n''}\,P_{q-q''}^{(m''-m,n'')}(1{-}2A^2)\,P_{q-q''}^{(m''-m,n'')}(2B^2{-}1)~~~ \\ & \text{when}~~~ n-n''\geq m''-m\geq0~, \\
\\
&0 ~~~ \text{otherwise}.
\end{cases}
\end{eqnarray}
\end{widetext}

a lot more text....
\end{document}

Any help would be greatly appreciated!

Answer 1

This works:

\documentclass[twocolumn]{article}
\usepackage{amsmath}
\usepackage{widetext}
\usepackage{flushend}
\usepackage{cuted}

\begin{document}

a lot of text ...

Here
\begin{widetext}
\begin{equation} \label{e27}
\begin{aligned}
&T_{nn''}^{mm''}=({-}1)^{p-p''}\,d_0^{\infty}\,J_{m-m''}(au)\,J_{n''}(bu)\,J_{n+1}(u)\,du = \\
&\qquad\begin{cases}
& \dfrac{(q{+}p'')!\,(p{-}p'')!}{(q{-}q'')!\,(p{+}q'')!}\,a^{m-m''}b^{n''}\,P_{p-p''}^{(m-m'',n'')}
(1{-}2A^2)P_{p-p''}^{(m-m'',n'')}(2B^2{-}1) \\ 
& \text{when}~~~n-n''\geq m-m''\geq0~,\\
\\
& \dfrac{(p{+}q'')!\,(q{-}q'')!}{(p{-}p'')!\,(q{+}p'')!}\,a^{m''-m}b^{n''}\,P_{q-q''}^{(m''-m,n'')}
(1{-}2A^2)\,P_{q-q''}^{(m''-m,n'')}(2B^2{-}1)~~~ \\ 
& \text{when}~~~ n-n''\geq m''-m\geq0~, \\
\\
&0\text{ otherwise}.
\end{cases}
\end{aligned}
\end{equation}
\end{widetext}

a lot more text....
\end{document}

The version used of widetext.sty has been downloaded from

https://svn.einsteintoolkit.org/documents/Paper_EinsteinToolkit_2010/widetext.sty

Answer 2

I'm rewriting my answer because my previous one was actually wrong. I apologize if it wasted anybody's time.

I also got error messages related to \prevdepth. The problem seems to arise in the strip environment used within widetext.

The error message states \prevdepth cannot work in horizontal mode. As Chris White noted, adding a newline solves it since (I guess) it puts TeX in vertical mode.

In order to get it work, I modified widetext.sty, to start a new paragraph before the strip environment and corrected the vertical space to avoid an empty line in second column, as follows:

...
\if@twocolumn
    \newenvironment{widetext}
    {%
        \par \vspace{-\baselineskip} % <-- this line added
        \begin{strip}

       ...

        \end{strip}
    \par \vspace{-\baselineskip}\noindent % <-- this line added
    \hspace*{-\parindent} % <-- this line added
    }
 ...

I had to add these two lines at the end to prevent extra indentation at the first paragraph after widetext, the origin of which I don't know.

See if it works for you.