[pracjourn-forum] A weird error

[Peter Flom]

I asked a question on the TeXHax list, and got the following suggested
code

<<<<<<BEGIN CODE   >>>>>

\documentclass{article}
\usepackage{amsmath}
\usepackage{pstricks,pst-node}
\usepackage{fancyvrb}

\begin{document}

\begin{minipage}{0.45\textwidth}
\begin{Verbatim}[commandchars=\|\[\]]
We use the symbol |rnode[i1][$\sqrt]{x}$ to denote the
|rnode[i2][\emph]{positive} square root
\end{Verbatim}
\end{minipage}
\hfill
\begin{minipage}{0.45\textwidth}
  We use the symbol \rnode{o1}{$\sqrt{x}$}
  to denote the  \rnode{o2}{\emph{positive}} square root
  \ncbar[linestyle=dotted,dotsep=1pt,nodesep=3pt,angle=90]{->}{i1}{o1}
 
\ncbar[linestyle=dotted,dotsep=1pt,nodesep=3pt,angle=-90]{->}{i2}{o2}
\end{minipage}

\end{document}

<<<<<<                 END CODE   >>>>>>>>>>>>>>>>>

this yielded the following error


<<<<             SNIPPET  FROM LOG FILE  >>>>>>

! Undefined control sequence.
<recently read> \c at lor@to at ps

l.18 ...tsep=1pt,nodesep=3pt,angle=90]{->}{i1}{o1}

<<<<       END SNIPPET>>>>

at this point, I say to myself "Huh?"    where is \c at lor@to at ps  ?


I looked for this error in the LaTeX companion, and it certainly has a
bit on undefined control sequence errors (on p. 912)  but I am mystified
how this paragraph helps me.....that command isn't in the .tex file!

While the above is on a .tex file that someone else sent me, this sort
of thing happens to me a lot, with undeifined control sequences for
things I never typed....

What am I missing?

Thanks

Peter
the newby in your midst



Peter L. Flom, PhD
Assistant Director, Statistics and Data Analysis Core
Center for Drug Use and HIV Research
National Development and Research Institutes
71 W. 23rd St
www.peterflom.com
New York, NY 10010
(212) 845-4485 (voice)
(917) 438-0894 (fax)