title: SparseMatrix and Vector addition broadcasting in Eigen
body: <p>I want to add a dense <code>VectorXf</code> to a <code>SparseMatrix</code>, and I know that I could do matrix + vector easily for dense matrix, <a href="https://eigen.tuxfamily.org/dox/group__TutorialReductionsVisitorsBroadcasting.html" rel="nofollow noreferrer">like this</a></p>
  
  <pre><code>  Eigen::MatrixXf mat(2,4);
    Eigen::VectorXf v(2);
  
    mat &lt;&lt; 1, 2, 6, 9,
           3, 1, 7, 2;
  
    v &lt;&lt; 0,
         1;
  
    //add v to each column of m
    mat.colwise() += v;
  </code></pre>
  
  <p>but how to do this for sparse matrix?</p>