code: def reciprocal(x, a, b, n):
      
      if n < 1:
          n = 1
      elif n > 5:
          n = 5
      if isinstance(x, list):
          y_l = []
          for x_v in x:
              y_l.append(a + b / x_v ** n)
          y = np.array(y_l)
      else:
          y = a + b / x ** n
      return y
docs: reciprocal function to the power n to fit convergence data