[OS X TeX] Underbracket woes

[Ross Moore]

> Greetings all,
> I'm trying to create brackets that connect terms in an equation much 
> like \underbrace, but straight instead of curly.  They should also be 
> nestable, so I could connect two inner terms while connection two outer 
> terms with a bigger bracket. (Physicists, I'm trying to make the 
> contraction operator used in quantum field theory, see Peskin & 
> Schroeder p. 89 for an example though they use overbrackets, which are 
> fine too).
> 
> Such a device is defined at 
> http://www.lyx.org/help/underbracket/bracket.php3 (and for brevity I 
> won't paste it here) but when I try something simple, like 
> \underbracket{AB}, I get the error message:
> 
> ! Use of \@ doesn't match its definition.
> \underbracket ->\@i
>                     fnextchar [ {\@underbracket}{\@underbracket 
> [\@brackethei...
> l.903 \underbracket
>                     {AB}

Someone forgot to put a \newcommand definition within

 \makeatletter
  ...
 \makeatother

Did you copy your definition of  \underbracket  from something
else and try to make adjustments ?


 
> I'm nowhere near competent enough in pure TeX to understand or fix the 
> problem, and I'm hoping someone wouldn't mind the, erm, uh, challenge.  

Fix this problem first, to at least see how your attempt actually works.
If it's enough, then you are set; if not, well then it becomes a more
interesting problem.   :-)


> Alternatively, is there a better way to do what I'm trying to do?  The 
> aforementioned textbook was clearly done in TeX, so there must be a way 
> -- perhaps I should bother the authors!  =:-)

No. THe author's job is to provide content, and ideas on how it is best
displayed. It is your job to implement those ideas effectively.
TeX can do it, but you may need to find the way.

It is always counter-productive to impose restrictions on authors due
to technical difficulties in the actual typesetting.


Hope this helps,

	Ross Moore

> Thanks,
> -Jeff Sherman
> 
> 
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Mac TeX info, resources, and news can be found at:
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