def rk_O(self, h, state_vec, fit_params):
O = state_vec[2]
return rk_utils.rk_X(h, O, state_vec, fit_params, self.dOdt)
def rk_D(self, h, state_vec, fit_params):
D = state_vec[0]
return rk_utils.rk_X(h, D, state_vec, fit_params, self.dDdt)
def rk_H(self, h, state_vec, fit_params):
H = state_vec[1]
return rk_utils.rk_X(h, H, state_vec, fit_params, self.dHdt)
def rk_T(self, h, state_vec, fit_params):
T = state_vec[3]
return rk_utils.rk_X(h, T, state_vec, fit_params, self.dTdt)