code: def H5(self):
          "Inverse difference moment."
          t = 1 + toeplitz(self.levels) ** 2
          repeated = np.tile(t[np.newaxis], (self.nobjects, 1, 1))
          return (1.0 / repeated * self.P).sum(2).sum(1f H5(self):
          "Inverse difference moment."
          t = 1 + toeplitz(self.levels) ** 2
          repeated = np.tile(t[np.newaxis], (self.nobjects, 1, 1))
          return (1.0 / repeated * self.P).sum(2).sum(1)
docs: Inverse difference moment.