title: Python least squares regression qs
body: <p>Why doesn't this code work? I am trying to do multi-variate regression.
  Four equations of the form:</p>
  
  <pre><code>Ax + By + c = d
  
  A + 2B + C = 0.2 etc.
  
  A = np.array([[ 0.,  1, 1.],
     [ 1.,  2, 1.],
     [ 2.,  3, 1.],
     [ 3.,  4, 1.]])
  
  y = np.array([-1, 0.2, 0.9, 2.1])
  m, c = np.linalg.lstsq(A, y)[0]
  print m, c
  </code></pre>
  
  <p>What am I doing wrong?</p>