title: Column-wise dot product in Eigen C++
body: <p>Is there an easy way to evaluate the column wise dot product of 2 matrices (lets call them <code>A</code> and <code>B</code>, of type <code>Eigen::MatrixXd</code>) that have dimensions <code>mxn</code>, without evaluating <code>A*B</code> or without having to resort to <code>for</code> loops? The resulting vector would need to have dimensions of <code>1xn</code> or <code>nx1</code>. Also, I'm trying to do this with Eigen in C++</p>