amtype">vec&lt; L, T, Q &gt; const &amp;&#160;</td>
          <td class="paramname"><em>v</em></td><td>)</td>
          <td></td>
        </tr>
      </table>
</div><div class="memdoc">

<p>Returns the base 2 log of x, i.e., returns the value y, which satisfies the equation x = 2 ^ y. </p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">v</td><td>log2 function is defined for input values of v defined in the range (0, inf+) in the limit of the type 