summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/doc/generic/FAQ-en/html/FAQ-braket.html
blob: a43bde32fba538eb17e47d359e65eea5bc95bbea (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
<head>
<title>UK TeX FAQ -- question label braket</title>
</head><body>
<h3>Set specifications and Dirac brackets</h3>
<p/>One of the few glaring omissions from TeX&rsquo;s mathematical
typesetting capabilities is a means of setting separators in the
middle of mathematical expressions.  TeX provides primitives called
<code>\</code><code>left</code> and <code>\</code><code>right</code>, which can be used to modify brackets (of
whatever sort) around a mathematical expression, as in:

<code>\</code><code>left(</code><code> &lt;expression&gt; </code><code>\</code><code>right)</code> &mdash; the size of the
parentheses is matched to the vertical extent of the expression.
<p/>However, in all sorts of mathematical enterprises one may find oneself
needing a <code>\</code><code>middle</code> command, to be used in expressions like
<blockquote>
<pre>
\left\{ x \in \mathbb{N} \middle| x \mbox{ even} \right\}
</pre>

</blockquote><p>
to specify the set of even natural numbers.  The 
<a href="FAQ-etex.html">e-TeX system</a>
defines just such a command, but users of Knuth&rsquo;s original need some
support.  Donald Arseneau&rsquo;s <i>braket</i> package provides commands
for set specifications (as above) and for Dirac brackets (and bras and
kets).  The package uses the e-TeX built-in command if it finds
itself running under e-TeX.
<dl>
<dt><tt><i>braket.sty</i></tt><dd><a href="ftp://cam.ctan.org/tex-archive/macros/latex/contrib/misc/braket.sty">macros/latex/contrib/misc/braket.sty</a>
</dl>
<p/><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=braket">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=braket</a>
</body>