title: Sparse Random Matrix with Eigen
body: <p>Is it possible to make a (sparse) matrix with the C++ Eigen library similar to this elegant python code I need to translate?</p>
  
  <pre><code>(np.random.rand(100,100)  &lt; 0.1) * np.random.rand(100,100)
  </code></pre>
  
  <p>e.g. a matrix filled with a certain proportion of random values.</p>