title: Creating a Breeze DenseMatrix using an existing List of Lists in Scala
body: <p>I've a </p>
  
  <pre><code>List[List[Int]] = List(List(1, 2, 3, 0, 0, 0, 0, 0, 0), List(0, 0, 0, 1, 2, 3, 0, 0, 0), List(0, 0, 0, 0, 0, 0, 1, 2, 3))
  </code></pre>
  
  <p>and I want to create a Matrix/DenseMatrix with 3 rows and 9 columns so that I can perform some Linear Algebra operations on it. </p>