Source of: /manual/en/function.acos.php
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<div id="function.acos" class="refentry">
<div class="refnamediv">
<h1 class="refname">acos</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">acos</span> — <span class="dc-title">Arc cosine</span></p>
</div>
<a name="function.acos.description"></a><div class="refsect1 description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">float</span> <span class="methodname"><b>acos</b></span>
( <span class="methodparam"><span class="type">float</span> <tt class="parameter">$arg</tt></span>
)</div>
<p class="para rdfs-comment">
Returns the arc cosine of <i><tt class="parameter">arg</tt></i>
in radians.
<b>acos()</b> is the complementary function of
<a href="function.cos.php" class="function">cos()</a>, which means that
<i>a==cos(acos(a))</i> for every value of a that is within
<b>acos()</b>' range.
</p>
</div>
<a name="function.acos.parameters"></a><div class="refsect1 parameters">
<h3 class="title">Parameters</h3>
<p class="para">
</p><dl>
<dt class="varlistentry">
<span class="term"><i><tt class="parameter">arg</tt></i>
</span>
</dt><dd class="listitem">
<p class="para">
The argument to process
</p>
</dd>
</dl>
<p>
</p>
</div>
<a name="function.acos.returnvalues"></a><div class="refsect1 returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
The arc cosine of <i><tt class="parameter">arg</tt></i>
in radians.
</p>
</div>
<a name="function.acos.seealso"></a><div class="refsect1 seealso">
<h3 class="title">See Also</h3>
<p class="para">
</p><ul class="simplelist">
<li class="member"><a href="function.cos.php" class="function" rel="rdfs-seeAlso">cos()</a> - Cosine</li>
<li class="member"><a href="function.acosh.php" class="function" rel="rdfs-seeAlso">acosh()</a> - Inverse hyperbolic cosine</li>
<li class="member"><a href="function.asin.php" class="function" rel="rdfs-seeAlso">asin()</a> - Arc sine</li>
<li class="member"><a href="function.atan.php" class="function" rel="rdfs-seeAlso">atan()</a> - Arc tangent</li>
</ul><p>
</p>
</div>
</div><?php manual_footer(); ?>
