[texhax] LaTeX help

[Robin Fairbairns]

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> In my LaTeX file I have inserted a figure within the 
> \begin{figure} ....   \end{figure}
> and using the command \includegraphics to include my EPS file(s).
> I tried to give the following caption:
> --------------------------------------------------------------------
>  \caption{Graphs of (i) $f(x):= |x|$ and 
> (ii) $f(x):= \left\{ \begin{array}{ll} x + 2 & \mbox{ if} \ x \le 1, \\
>                    x^2 - 1 & \mbox{ if} \ x > 1; \end{array} \right.$}
> --------------------------------------------------------------------
> However, while compiling, I get the following error message:
>  --------------------------------------------------------------------
> Argument of \@caption has an extra }.
> <inserted text>
>                 \par
> l.1404 ...mbox{ if} \ x > 1; \end{array} \right.$}
> --------------------------------------------------------------------
> I know for sure that there is no extra brace.

there's an answer in the faq about precisely the error message you
have.  in your case, the fragile command is \begin ==> use
\protect\begin instead.

> Nevertheless it is annoying to have this error message. Can you tell
> me how to avoid it? Could it be because the array environment (and the
> \\ comand to go to next line) is forbidden within \caption?

\\ isn't forbidden, it just doesn't work: the nearest to "forbidding"
\\ is the failure to do anything to make it work.  what should it do
in the list of figures, for example.

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