code: def greenhall_sw(t, alpha):
      
      alpha = int(alpha)
      if alpha == 2:
              return -np.abs(t)
      elif alpha == 1:
          if t == 0:
              return 0
          else:
              return pow(t, 2)*np.log(np.abs(t))
      elif alpha == 0:
          return np.abs(pow(t, 3))
      elif alpha == -1:
          if t == 0:
              return 0
          else:
              return pow(t, 4)*np.log(np.abs(t))
      elif alpha == -2:
          return np.abs(pow(t, 5))
      elif alpha == -3:
          if t == 0:
              return 0
          else:
              return pow(t, 6)*np.log(np.abs(t))
      elif alpha == -4:
          return np.abs(pow(t, 7))
  
      assert(0)
docs: Eqn (7) from Greenhall2004