code: def _get_initial_residual(self, x0):
          '''Return the projected initial residual.
  
          Returns :math:`MPM_l(b-Ax_0)`.
          '''
          if x0 is None:
              Mlr = self.linear_system.Mlb
          else:
              r = self.linear_system.b - self.linear_system.A*x0
              Mlr = self.linear_system.Ml*r
  
          PMlr, self.UMlr = self.projection.apply_complement(Mlr, return_Ya=True)
          MPMlr = self.linear_system.M*PMlr
          MPMlr_norm = utils.norm(PMlr, MPMlr, ip_B=self.linear_system.ip_B)
          return MPMlr, PMlr, MPMlr_norf _get_initial_residual(self, x0):
          '''Return the projected initial residual.
  
          Returns :math:`MPM_l(b-Ax_0)`.
          '''
          if x0 is None:
              Mlr = self.linear_system.Mlb
          else:
              r = self.linear_system.b - self.linear_system.A*x0
              Mlr = self.linear_system.Ml*r
  
          PMlr, self.UMlr = self.projection.apply_complement(Mlr, return_Ya=True)
          MPMlr = self.linear_system.M*PMlr
          MPMlr_norm = utils.norm(PMlr, MPMlr, ip_B=self.linear_system.ip_B)
          return MPMlr, PMlr, MPMlr_norm
docs: Return the projected initial residual.
  
          Returns :math:`MPM_l(b-Ax_0)`.