code: def EI(inc):
      
      poly_tk03 = [3.15976125e-06,  -3.52459817e-04,  -
                   1.46641090e-02,   2.89538539e+00]
      return poly_tk03[0] * inc**3 + poly_tk03[1] * inc**2 + poly_tk03[2] * inc + poly_tk03[3]
docs: Given a mean inclination value of a distribution of directions, this
      function calculates the expected elongation of this distribution using a
      best-fit polynomial of the TK03 GAD secular variation model (Tauxe and
      Kent, 2004).
  
      Parameters
      ----------
      inc : inclination in degrees (int or float)
  
      Returns
      ---------
      elongation : float
  
      Examples
      ---------
      >>> pmag.EI(20)
      2.4863973732
      >>> pmag.EI(90)
      1.0241570135500004