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From: sanders-malcolm@CS.YALE.EDU (SANDERS-MALCOLM)
Newsgroups: comp.text.tex
Subject: Re: Latex bug???
Message-ID: <28941@cs.yale.edu>
Date: 20 Feb 91 17:56:45 GMT
References: <1991Feb20.145148.13403@polaris.utu.fi>
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In-reply-to: knuutila@tucos.utu.fi's message of 20 Feb 91 14:51:48 GMT

In article <1991Feb20.145148.13403@polaris.utu.fi> knuutila@tucos.utu.fi (Timo Knuutila) writes:

>  Just encountered the following. Can someone please explain why the text
>  produces `weird errors' with LaTeX.
>
>  === EXAMPLE TEXT ===
>  \documentstyle{report}
>  \begin{document}
>  $$\begin{array}{l}
>  [b_1]\\
>  \ldots\\
>  [b_m]
>  \end{array}$$
>  \end{document}
>
>   === LOG FILE ===
   [much complaining ...]
>   === END OF LOG FILE ===
>
>   The following works just fine ({} inserted before [b_m]):
...

If you check out the definition of the latex "\\" command(section C.1.6
in the Latex Manual), you will find that it has an optional length 
argument and the proper syntax is "\\[len]".  As long as the next 
character after a "\\" is anything other than "[", then there is
no problem. If the next character *is* a "[", however, then the 
following text must be a length followed by "]", or else latex 
complains.  The string, "b_m" is not a lenght, hence, putting "\\[b_m]" 
causes a problem. Using "\\{}[b_m]" instead fixes it.

Malcolm Sanders
Applied Physics
Yale University			sanders@ycc.yale.edu