# [texhax] question

John Wheeler jwheeler at ucsd.edu
Wed Jan 30 21:27:32 CET 2013

Barbara,
I've seen so many responses like this from you:  so kind, so helpful, so
precise, and obviously having taken some serious work to find
the precise location of the error.  I think you should be declared  a
National Treasure!
John Wheeler
grateful amateur LaTeX user
On 01/30/2013 09:11 AM, Barbara Beeton wrote:
> hello, antonio,
>
>      I have a vexing problem with latex as described in the attending file.
>      I am not technically competent, but an applied mathematician struggling to
>      arrive at a decent manuscript. Can you help?
>
> the problem is with the math expression in the
> \section text of the file III62.tex.
>
> here is what you have (line breaks added):
>
>    \section{The  case of vector processes:
>     $\underline{X}=S\left[\underline{a}\right] > +\underline{B}$}
>
> the section heading is what is called a
> "moving argument" -- this data is saved
> and inserted (in the book class) into a
> running head.  if any command in a moving
> argument is "fragile", it will cause a
> problem, and not always in an obvious way.
> that is what is happening here.
>
> the command \underline is fragile, and the
> way to fix it is, whenever it is in a moving
> argument, to "protect" it.  this is done by
> inserting the command \protect just before
> the fragile command:
>
>    \section{The  case of vector processes:
>     $\protect\underline{X}=S\left[\protect\underline{a}\right] > +\protect\underline{B}$}
>
> this should solve your problem.
>
> other commands with moving arguments are
> any "section" heading (\chapter, \subsection,
> ...), \caption, and \footnote.
>
> while the recommendation from william adams
> won't solve your current problem, it's good
> also, i think you would benefit from reading
> some basic latex documentation.  some good
> resources are "the not so short guide" (if
> you have a tex live installation, you can
> access this by typing
>    texdoc lshort
> at the command line, or you can see it from
> ctan -- go to
>    http://www.ctan.org/search/
> and enter  lshort  as the search argument)
> and the documentation for amsmath,
>    texdoc amsldoc
> or
>    ftp://ftp.ams.org/pub/tex/doc/amsmath/amsldoc.pdf
>
> good luck.
> 						-- bb
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