def obfn_reg(self):
        """Compute regularisation term and contribution to objective
        function.
        """

        rl1 = np.linalg.norm((self.wl1 * self.obfn_gvar()).ravel(), 1)
        rl2 = 0.5*np.linalg.norm(self.obfn_gvar())**2
        return (self.lmbda*rl1 + self.mu*rl2, rl1, rl2)
Compute regularisation term and contribution to objective
        function.