title: How to do colwise operations in Eigen
body: <p>I am doing this a lot:</p>
  
  <pre><code>auto f_conj = f.conjugate(); //f is a MatrixXcf, so is C;
  for(n=0;n&lt;X.cols();++n)
      C.col(n) = X.col(n).cwiseProduct(f_conj);
  </code></pre>
  
  <p>Am I not supposed to be able to do something like </p>
  
  <pre><code>C.colwise() = X.colwise().cwiseProduct(f_conj)
  </code></pre>
  
  <p>instead?</p>