title: Element-wise subtraction of two numpy arrays
body: <p>I have two numpy arrays say 'a' and 'b' having the dimensions (327600,5) and (3,5) respectively. I want to do an element-wise subtraction of the two arrays. How would I go about doing this without a loop?. </p>
  
  <p>When I do a[0] - b I get a (3,5) array. I want to get a (327600,3,5) array as the result after subtraction. </p>