rec-log2

log base 3 of x

W3C sample	WIRIS
	$\log_{3}x$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <log/>
    <logbase>
      <cn>3</cn>
    </logbase>
    <ci>x</ci>
  </apply>
</math>

Author: MathML 2 Recommendation