title: python numpy/scipy curve fitting
body: <p>I have some points and I am trying to fit curve for this points. I know that there exist <code>scipy.optimize.curve_fit</code> function, but I do not understand documentation, i.e how to use this function.</p>
  
  <p>My points: <code>np.array([(1, 1), (2, 4), (3, 1), (9, 3)])</code></p>
  
  <p>Can anybody explain how to do that?</p>