title: Get matrix product of 3 matrices
body: <p>I have 3, 3X3 matrices stored in numpy arrays.
  I want to get the product, to compute a rotation matrix.</p>
  
  <p>Currently what I am doing is 
  <code>rotation_matrix = (a * b * c)</code> but I don't know if this is the correct way to multiply matrices - should I be using <code>.dot</code> I have also tried with <code>rotation_matrix = pre_rotation.dot(result_pre_tilt).dot(post_rotation)</code> </p>
  
  <p>and <code>rotation_matrix = np.multiply(result_pre_tilt, pre_rotation, post_rotation)</code></p>
  
  <pre><code>a = np.array(
  [[-0.25091924  0.         -0.        ]
  [-0.         -0.35485339  0.        ]
  [ 0.          0.          0.70710678]])
  
  b = np.array(
  [[ 0.10040533 -0.          0.        ]
  [ 0.          0.28953198 -0.        ]
  [ 0.          0.          0.31056766]])
  
  c = np.array(
  [[  6.12323400e-17   0.00000000e+00  -1.00000000e+00]
  [  0.00000000e+00   1.00000000e+00   0.00000000e+00]
  [  1.00000000e+00   0.00000000e+00   6.12323400e-17]])
  </code></pre>