title: Arrays product in Python
body: <p>I have defined couple of arrays in Python but I am having problem in calculation of the product.</p>
  
  <pre><code>import numpy as np
  phi = np.array([[ 1.,  1.],[ 0.,  1.]])
  P = np.array([[ 999.,    0.],[   0.,  999.]])
  np.dot(phi, P, phi.T)
  </code></pre>
  
  <p>I get the error:
  ValueError: output array is not acceptable (must have the right type, nr dimensions, and be a C-Array)</p>
  
  <p>But I do not know what is the problem, since the size of matrix or array is 2 by 2</p>