[texhax] parenthesis problem in LaTeX

Reinhard Kotucha reinhard.kotucha at web.de
Sat Jan 17 00:56:55 CET 2009


Tom Schneider writes:
 > Reinhard:
 > 
 > > Tom Schneider writes:
 > >  > Here's a puzzle for the sharp folks on this list!
 > > 
 > > Hi Tom,
 > > the problem is obviously that unlike "silent", the word "ring"
 > > contains the letter "g" which has a descender, as Steve explained
 > > already.
 > > 
 > > How can you achieve that all braces have the same size?  There are
 > > many possible solutions.  You could use struts or phantoms.
 > > 
 > > However, there is a very elegant solution.  All *tex programs except
 > > Knuth's tex itself are using the eTeX extensions for a couple of years
 > > now.
 > > 
 > > $ pdftex \\relax\\bye
 > > This is pdfTeXk, Version 3.1415926-1.40.9 (Web2C 7.5.7)
 > >  %&-line parsing enabled.
 > > entering extended mode  <===========
 > > No pages of output.
 > > Transcript written on texput.log.
 > > 
 > > You are using \left and \right already, but eTeX provides a new
 > > primitive called \middle.  See:
 > > 
 > >   http://tug.ctan.org/tex-archive/systems/e-tex/v2/doc/etex_man.pdf
 > > 
 > > section 3.9 on page 12.
 > 
 > Ok, thanks.  I'm unsure how it would be used in this case.

Hi Tom,
a simple example:

\begin{equation}
  \left( a+b \middle) \times \middle( \frac{a}{b} \right)
\end{equation}

As always: Whenever you've found out how things work, then you also
understand the manual. :)
But there is a hint in the manual though it can easily be overlooked:
\middle<delimiter>.  This explains the error message you got 
(! Missing delimiter).

BTW, here is a single-line example file for plain TeX:

$$ \left( a+b \middle) \times \middle( a \over b \right) $$ \bye

Please note that it doesn't work with tex.  You have to use etex,
pdftex, pdfetex, ... instead.  I didn't try, but I'm very sure that
you can use \middle in Context, eplain, texinfo,... too.  In short: It
works on any machine which prints "entering extended mode" to screen.

Regards,
  Reinhard

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