&lt; Dim, System &gt;, Y &gt;&gt;</span></h2>
<p>boost::units::add_typeof_helper&lt;quantity&lt; unit&lt; Dim, System &gt;, X &gt;, quantity&lt; unit&lt; Dim, System &gt;, Y &gt;&gt;</p>
</div>
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../boost_units/Referen