def test_estimate_friedrich_coefficients(self):
        """
        Estimate friedrich coefficients
        """
        default_params = {"m": 3, "r": 30}

        # active Brownian motion
        ds = velocity(tau=3.8, delta_t=0.05, R=3e-4, seed=0)
        v = ds.simulate(10000, v0=np.zeros(1))
        coeff = _estimate_friedrich_coefficients(v[:, 0], **default_params)
        self.assertLess(abs(coeff[-1]), 0.0001)

        # Brownian motion
        ds = velocity(tau=2.0 / 0.3 - 3.8, delta_t=0.05, R=3e-4, seed=0)
        v = ds.simulate(10000, v0=np.zeros(1))
        coeff = _estimate_friedrich_coefficients(v[:, 0], **default_params)
        self.assertLess(abs(coeff[-1]), 0.0001)