rec-arg1

arg(x+iy)

W3C sample	WIRIS
	$\mathop{\arg }(x+iy)$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <arg/>
    <apply>
      <plus/>
      <ci>x</ci>
      <apply>
        <times/>
        <cn> &#x02148;</cn>
        <ci>y</ci>
      </apply>
    </apply>
  </apply>
</math>

Author: MathML 2 Recommendation