<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.atan" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>atan</refname>
  <refpurpose>Arc tangent</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
   <methodsynopsis>
    <type>float</type><methodname>atan</methodname>
    <methodparam><type>float</type><parameter>arg</parameter></methodparam>
   </methodsynopsis>
  <para>
   Returns the arc tangent of <parameter>arg</parameter> in radians.
   <function>atan</function> is the complementary function of
   <function>tan</function>, which means that
   <literal>a==tan(atan(a))</literal> for every value of a that is within
   <function>atan</function>'s range.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>arg</parameter></term>
     <listitem>
      <para>
       The argument to process
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   The arc tangent of <parameter>arg</parameter> in radians.
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>tan</function></member>
    <member><function>atanh</function></member>
    <member><function>asin</function></member>
    <member><function>acos</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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