<doc>
  <legacy_id>2101</legacy_id>
  <name>atan</name>
  <type>function</type>
  <syntax>
    <example>the atan of <i>number</i></example>
    <example>atan(<i>number</i>)</example>
  </syntax>
  <library></library>
  <objects>
  </objects>
  <synonyms>
  </synonyms>
  <classification>
    <category>Math, Logic, &amp; Dates</category>
  </classification>
  <references>
    <constant tag="pi">pi Constant</constant>
  </references>
  <history>
    <introduced version="1.0">Added.</introduced>
  </history>
  <platforms>
    <mac/>
    <windows/>
    <linux/>
    <ios/>
    <android/>
  </platforms>
  <classes>
    <desktop/>
    <server/>
    <web/>
    <mobile/>
  </classes>
  <security>
  </security>
  <summary><glossary tag="return">Returns</glossary> the arc tangent of a number in <glossary tag="radian">radians</glossary>.</summary>
  <examples>
    <example>atan(0)</p><p>atan(tan(-1))</example>
    <example>the atan of vectorMagnitude</example>
  </examples>
  <description>
    <p>Use the <b>atan</b> <control_st tag="function">function</control_st> to find the arc tangent of a number.</p><p/><p><b>Parameters:</b></p><p>The <i>number</i> is a positive or <glossary tag="negative">negative</glossary> number, or an <glossary tag="expression">expression</glossary> that <glossary tag="evaluate">evaluates</glossary> to a number.</p><p/><p><b>Value:</b></p><p>The <b>atan</b> <control_st tag="function">function</control_st> <glossary tag="return">returns</glossary> a number between -pi/2 and pi/2.</p><p/><p><b>Comments:</b></p><p>The arc tangent of <i>number</i> is an angle whose tangent is equal to <i>number</i>. In other words, <b>atan</b> is an <keyword tag="inverse">inverse</keyword> of the <function tag="tan">tan</function> <control_st tag="function">function</control_st>.</p><p>The result of the <b>atan</b> function is <glossary tag="return">returned</glossary> in <glossary tag="radian">radians</glossary>. To get this result in <glossary tag="degree">degrees</glossary>, use the following <href tag="dictionary/property/2381.xml">custom function</href>:</p><p/><p>  function atanInDegrees theMagnitude</p><p>    return atan(theMagnitude) * 180 / pi</p><p>  end atanInDegrees</p>
  </description>
</doc>