# [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
> >
> > 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:

$$\left( a+b \middle) \times \middle( \frac{a}{b} \right)$$

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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