code: def solve_t(self, Mt):
          
          if len(Mt.shape)==2:    _Mt = Mt[:, :, sp.newaxis]
          else:                   _Mt = Mt
          LMt = vei_CoR_veX(_Mt, R=self.Lr(), C=self.Lc())
          DLMt = self.D()[:, :, sp.newaxis] * LMt
          RV = vei_CoR_veX(DLMt, R=self.Lr().T, C=self.Lc().T)
          if len(Mt.shape)==2:    RV = RV[:, :, 0]
          return RV
docs: Mt is dim_r x dim_c x d tensor