[pracjourn-forum] A weird error

[Christina Thiele]

Sooo ... who's gonna take all this wonderful stuff and turn it into an
article for the next issue?! Peter Flom's query has yielded a good
chunk of directly applicable stuff -- surely we could turn it into
something for public consumption!

By the way, Lance, just when _is_ the next TPJ issue supposed to come
out? Just so I can plan my work load and holidays ;-))

Ch.

====

Peter Flynn writes:
> 
> ...
> > 
> > <<<<             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>>>>
> 
> That file processes without error on my system (attached).
> 
> > at this point, I say to myself "Huh?"    where is \c at lor@to at ps  ?
> 
> The @ signs indicate that this is an internal command, one used in the
> internal controls of LaTeX or a package, and one that users (we) are not
> ever meant to see :-)
> 
> >From the name it looks like it's doing something with color to ps
> (PostScript?), so my guess is it's in one of the packages...but
> 
> $ for f in amsmath pstricks pst-node fancyvrb; do grep -H c at lor@to at ps
> `dirname \`kpsewhich $f.sty\``*; done
> 
> produces no output, so it's elsewhere. A small steam-hammer like this
> 
> $ find /usr/TeX/texmf/tex/latex -name '*.sty' -exec grep -H c at lor@to at ps
> {} \;
> 
> soon turns up:
> 
> /usr/TeX/texmf/tex/latex/changebar/changebar.sty: 
> \def\cb at ps@color{\expandafter\c at lor@to at ps\cb at current@color\@@}}
> /usr/TeX/texmf/tex/latex/graphics/pstcol.sty:        
> \c at lor@to at ps\csname\string\color @#1\endcsname\@@}}}
> /usr/TeX/texmf/tex/latex/texpower/tppstcol.sty: 
> \c at lor@to at ps\csname\string\color @#1\endcsname\@@\space%
> /usr/TeX/texmf/tex/latex/xcolor/xcolor.sty:    
> {\noexpand\edef\noexpand#2{\noexpand\expandafter\noexpand\c at lor@to at ps
> /usr/TeX/texmf/tex/latex/xcolor/xcolor.sty:           
> \c at lor@to at ps\csname\string\color @#1\endcsname\@@}}}
> 
> of which pstcol.sty looks the most possible for your case, and at a
> guess I'd say you may have an out-of-date copy of pstricks.
> 
> > 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!
> 
> No, those internal-only commands can't be used in ordinary LaTeX files
> because "@" isn't allowed in control sequences except within packages
> (or between \makeatletter and \makeatother).
> 
> > 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?
> 
> Almost every command invokes other commands, which invoke other 
> commands, and so on, and many of them go deep into the bowels of LaTeX,
> using commands which you (and I) certainly never come across in a 
> lifetime of LaTeXing.
> 
> LaTeX is not a flat control surface, it has many dimensions :-)
> 
> ///Peter
> 
> ...