title: Issue with operand types
body: <p>I get the following error:</p>
  
  <blockquote>
    <p>error: no match for 'operator-' (operand types are 'QVector' and 'const float')</p>
  </blockquote>
  
  <p>when trying to do:</p>
  
  <pre><code>dist.push_back(qPow((clusterMeanCoordinate[t].at(i) - hash_notClustered[t].at(point)), 2) + qPow((clusterMeanCoordinate[w] - hash_notClustered[w].at(point)), 2));
  </code></pre>
  
  <p>Note that:</p>
  
  <pre><code>QHash&lt;int, QVector&lt;float&gt; &gt; clusterMeanCoordinate;
  QHash&lt;int, QVector&lt;float&gt; &gt; hash_notClustered;
  QVector&lt;float&gt; dist;
  </code></pre>