no">   38</span>&#160; </div>
<div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;        <span class="keyword">template</span>&lt;<span class="keyword">typename</span> T, <span class="keyword">typename</span> Vec&gt;</div>
<div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;        <span class="keyword">using</span> return_type_scalar_multiplication = <span class="keyword">typename</span> std::enable_if&lt;</div>
<div class="line"><a name="l00041"></a><sp