code: def rms(self, x, params=()):
          
          internal_x, internal_params = self.pre_process(np.asarray(x),
                                                         np.asarray(params))
          if internal_params.ndim > 1:
              raise NotImplementedError("Parameters should be constant.")
          result = np.empty(internal_x.size//self.nx)
          for idx in range(internal_x.shape[0]):
              result[idx] = np.sqrt(np.mean(np.square(self.f_cb(
                  internal_x[idx, :], internal_params))))
          return result
docs: Returns root mean square value of f(x, params)