def METHOD_NAME(self):
    fo = burnman.minerals.HP_2011_ds62.fo()
    pressures = np.linspace(1.0e9, 2.0e9, 8)
    temperatures = np.ones_like(pressures) * fo.params["T_0"]
    PTV = np.empty((len(pressures), 3))
    for i in range(len(pressures)):
        fo.set_state(pressures[i], temperatures[i])
        PTV[i] = [pressures[i], temperatures[i], fo.V]
    params = ["V_0", "K_0", "Kprime_0"]
    fitted_eos = burnman.eos_fitting.fit_PTV_data(fo, params, PTV, verbose=False)
    zeros = np.zeros_like(fitted_eos.pcov[0])
    self.assertArraysAlmostEqual(fitted_eos.pcov[0], zeros)