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<h4 class="subsection" id="Anonymous-Functions-1"><span>11.12.2 Anonymous Functions<a class="copiable-link" href="#Anonymous-Functions-1"> ¶</a></span></h4>
<p>Anonymous functions are defined using the syntax
</p>
<div class="example">
<pre class="example-preformatted">@(<var class="var">argument-list</var>) <var class="var">expression</var>
</pre></div>
<p>Any variables that are not found in the argument list are inherited from
the enclosing scope. Anonymous functions are useful for creating simple
unnamed functions from expressions or for wrapping calls to other
functions to adapt them for use by functions like <code class="code">quad</code>. For
example,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">f = @(x) x.^2;
quad (f, 0, 10)
⇒ 333.33
</pre></div></div>
<p>creates a simple unnamed function from the expression <code class="code">x.^2</code> and
passes it to <code class="code">quad</code>,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">quad (@(x) sin (x), 0, pi)
⇒ 2
</pre></div></div>
<p>wraps another function, and
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">a = 1;
b = 2;
quad (@(x) betainc (x, a, b), 0, 0.4)
⇒ 0.13867
</pre></div></div>
<p>adapts a function with several parameters to the form required by
<code class="code">quad</code>. In this example, the values of <var class="var">a</var> and <var class="var">b</var> that
are passed to <code class="code">betainc</code> are inherited from the current
environment.
</p>
<p>Note that for performance reasons it is better to use handles to existing
Octave functions, rather than to define anonymous functions which wrap an
existing function. The integration of <code class="code">sin (x)</code> is 5X faster if the code
is written as
</p>
<div class="example">
<pre class="example-preformatted">quad (@sin, 0, pi)
</pre></div>
<p>rather than using the anonymous function <code class="code">@(x) sin (x)</code>. There are many
operators which have functional equivalents that may be better choices than an
anonymous function. Instead of writing
</p>
<div class="example">
<pre class="example-preformatted">f = @(x, y) x + y
</pre></div>
<p>this should be coded as
</p>
<div class="example">
<pre class="example-preformatted">f = @plus
</pre></div>
<p>See <a class="xref" href="Operator-Overloading.html">Operator Overloading</a>, for a list of operators which also have a
functional form.
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