title: Scalar multiplication two 2darrays
body: <p>I have following Problem. 
  I have two 2d arrays with the size (4,2)</p>
  
  <pre><code>a = [[1 1]
  [1 1]
  [1 1]
  [2 2]] 
  
  b = [[2 3]
  [2 2] 
  [3 4] 
  [1 4]] 
  </code></pre>
  
  <p>and i want to do column wise scalar multiplication</p>
  
  <pre><code>a * b = [[2, 3] 
  [2 2]
  [3 4]
  [2 8]]
  </code></pre>