def obfn_gvar(self):
        r"""Variable to be evaluated in computing :math:`g(\cdot)`,
        depending on the ``gEvalY`` option value.
        """

        return self.Y if self.opt['gEvalY'] else np.mean(self.X, axis=-1)
r"""Variable to be evaluated in computing :math:`g(\cdot)`,
        depending on the ``gEvalY`` option value.