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<head>
<title>UK TeX FAQ -- question label limits</title>
</head><body>
<h3>Sub- and superscript positioning for operators</h3>
<p/>The commonest hand-written style for expressions is to place the limit
expressions on operators such as <code>\</code><code>sum</code> and <code>\</code><code>int</code> physically
above and below the operator.  In (La)TeX, we write these limit
expressions using sub- and superscripts applied to the operator, but
they don&rsquo;t always appear in the &ldquo;handwritten&rdquo; way in TeX&rsquo;s
output.
<p/>The reason is, that when an expression appears in non-display maths,
in running text (and is therefore in TeX <code>\</code><code>textstyle</code>), placing
the limits thus could lead to ragged line spacing (and hence
difficult-to-read text).  It is therefore common (in <code>\</code><code>textstyle</code>)
to place the limits as one would sub- and superscripts of variables.
<p/>This is not universally satisfactory, so the primitive <code>\</code><code>limits</code> is
provided:
<blockquote>
<pre>
$\sum\limits_{n=1}^{m} ...$
</pre>
</blockquote><p>
which will place the limits right above and below the symbol (and be
blowed to the typography...).
<p/>Contrariwise, you may wish to change the arrangement of the limits
when in <code>\</code><code>displaystyle</code>.  For this purpose, there&rsquo;s a corresponding
<code>\</code><code>nolimits</code>:
<blockquote>
<pre>
\[\sum\nolimits_{n=1}^{m} ...\]
</pre>
</blockquote><p>
which will place the limits as they would be in <code>\</code><code>textstyle</code>.
<p/>Alternatively, one can manipulate the
<code>\</code><code>textstyle</code>/<code>\</code><code>displaystyle</code> state of the mathematics.  To get
&ldquo;<code>\</code><code>limits</code> placement&rdquo; in inline maths,
<blockquote>
<pre>
$\displaystyle\sum_{n=1}^{m} ...$
</pre>
</blockquote><p>
and for &ldquo;<code>\</code><code>nolimits</code> placement&rdquo; in display maths,
<code>\</code><code>nolimits</code>:
<blockquote>
<pre>
\[\textstyle\sum_{n=1}^{m} ...\]
</pre>
</blockquote><p>
will serve.  Either of these forms may have effects other than on the
operator you&rsquo;re considering, but there are still those who prefer this
formulation.
<p/>Remember, if you&rsquo;re 
<a href="FAQ-newfunction.html">declaring a special operator of your own</a>, the
AMSLaTeX functions (that you ought to be using) allow you to choose
how limits are displayed, at definition time.
<p/>(Note that the macro <code>\</code><code>int</code> normally has <code>\</code><code>nolimits</code> built in to
its definition.  There is an example in the TeXbook to show how odd
<code>\</code><code>int</code><code>\</code><code>limits</code> looks when typeset.)
<p/><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=limits">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=limits</a>
</body>