[pstricks] ncbar outside pstricks

[David Arnold]

All,

I've attached a file (won't compile for you as many supporting files are missing) so that you can see what our preamble contains:

This block of code contains my question.

code_snippet:

We ``group'' the first and second terms, noting that we can factor  $5u$ out of both of these terms. Then we ``group'' the third and fourth terms, noting that we can factor $-8$ out of both of these terms.
\begin{align*}
5\rnode[t]{A}{u^2} -10\rnode[t]{B}{uw} -8\rnode[t]{C}{u} +16\rnode[t]{D}{w}
&=5u\,{\color{red}(u-2w)} -8\,{\color{red}(u-2w)}\\
\intertext{Now we note that we can factor a $u-2w$ out of both of these terms.}
&=(5u-8){\color{red}(u-2w)}
\end{align*}
\ncbar[linecolor=red,angle=270,arm=7pt,nodesep=3pt]{<->}{A}{B}
\ncbar[linecolor=red,angle=270,arm=7pt,nodesep=3pt]{<->}{C}{D}

In our Optimath system (msenux.redwoods.edu/optimath), we compile this file with a script, whose main lines are:

    system "latex --shell-escape $testbank-preview.tex";
    system "dvips -o $testbank-preview-pics.ps $testbank-preview.dvi";
    system "ps2pdf -dAutoRotatePages=/None $testbank-preview-pics.ps $testbank-preview-pics.pdf";
    system "pdflatex  --shell-escape $testbank-preview.tex";

This results in the following error:

ABD: EveryShipout initializing macros
(/usr/local/texlive/2010/texmf-dist/tex/latex/amsfonts/umsa.fd)
(/usr/local/texlive/2010/texmf-dist/tex/latex/amsfonts/umsb.fd))
! Incomplete \iffalse; all text was ignored after line 67.
<inserted text> 
                \fi 
<*> dev-preview.tex
                   
? 

I wondering if there is an easy way to recode my code_snippet above so that it will compile in our system?

Thanks.

David Arnold
College of the Redwoods
http://msemac.redwoods.edu/~darnold/index.php