def _update_solution_data(self, s, HH, CC, C0):
        """ Returns the voltage angle and generator set-point vectors.
        """
        x = s["x"]
        Va_v = self.om.get_var("Va")
        Pg_v = self.om.get_var("Pg")

        Va = x[Va_v.i1:Va_v.iN + 1]
        Pg = x[Pg_v.i1:Pg_v.iN + 1]
#        f = 0.5 * dot(x.T * HH, x) + dot(CC.T, x)

        s["f"] = s["f"] + C0

        # Put the objective function value in the solution.
#        solution["f"] = f

        return Va, Pg