title: Subtract corresponding elements from 2 lists that both contain column matrices
body: <p>I have 2 lists </p>
  
  <pre><code>A= matrix([[ 9],
              [5],
              [7],
              [ 8]]), matrix([[2],
              [3],
              [7],
              [8])]
  
  B = matrix([[ 3],
              [2],
              [1],
              [ 4]]), matrix([[2],
              [3],
              [2],
              [5])]
  </code></pre>
  
  <p>I want subtract the first matrix in the second list B from the first matrix in the first list A. To get the matrix </p>
  
  <pre><code>    matrix([[3],
              [3],
              [6],
              [4])
  </code></pre>
  
  <p>then the second from the second, and add these new matrices to a new list C. </p>
  
  <p>I tried the code </p>
  
  <pre><code> C=list()
      for j in A :
          for k in B: 
              C.append(j-k)
  </code></pre>
  
  <p>But it's not giving the correct answers . What are your suggestions? </p>