inner product two rows in matrix C++ with Eigen : <p>I want to do an inner product as below. 
MatrixXd a= [1,2,3,4]
MatrixXd b= [1,2,3,4]</p>

<p>a*b = [1,4,9,16]  &lt;=> c[i] = a[i]*b[i].</p>

<p>How to do it with Eigen MatrixXd?</p>

<p>Thanks.</p>
