code: def cnst_A1T(self, Y1):
          r
  
          Y1f = sl.rfftn(Y1, None, axes=self.cri.axisN)
          return sl.irfftn(np.conj(self.GDf) * Y1f, self.cri.Nv,
                           self.cri.axisN)
docs: r"""Compute :math:`A_1^T \mathbf{y}_1` component of
          :math:`A^T \mathbf{y}`. In this case :math:`A_1^T \mathbf{y}_1 =
          (\Gamma_0^T \;\; \Gamma_1^T \;\; \ldots) \mathbf{y}_1`.