def ystep(self):
        r"""Minimise Augmented Lagrangian with respect to
        :math:`\mathbf{y}`.
        """

        self.Y = sp.proj_l1(self.AX + self.U, self.gamma,
                            axis=self.cri.axisN + (self.cri.axisC,
                                                   self.cri.axisM))
        super(ConvBPDNProjL1, self).ystep()
r"""Minimise Augmented Lagrangian with respect to
        :math:`\mathbf{y}`.