title: Array elementwise operations
body: <p>I have two input arrays x and y of the same shape.  I need to run each of their elements with matching indices through a function, then store the result at those indices in a third array z.  What is the most pythonic way to accomplish this?  Right now I have four four loops - I'm sure there is an easier way.</p>
  
  <pre><code>x = [[2, 2, 2],
       [2, 2, 2],
       [2, 2, 2]]
  
  y = [[3, 3, 3],
       [3, 3, 3],
       [3, 3, 1]]
  
  def elementwise_function(element_1,element_2):
      return (element_1 + element_2)
  
  z = [[5, 5, 5],
       [5, 5, 5],
       [5, 5, 3]]
  </code></pre>
  
  <p>I am getting confused since my function will only work on individual data pairs.  I can't simply pass the x and y arrays to the function.</p>