code: def _pwl_costs(self, ny, nxyz, ipwl):
          
          any_pwl = int(ny > 0)
          if any_pwl:
              y = self.om.get_var("y")
              # Sum of y vars.
              Npwl = csr_matrix((ones(ny), (zeros(ny), array(ipwl) + y.i1)))
              Hpwl = csr_matrix((1, 1))
              Cpwl = array([1])
              fparm_pwl = array([[1., 0., 0., 1.]])
          else:
              Npwl = None#zeros((0, nxyz))
              Hpwl = None#array([])
              Cpwl = array([])
              fparm_pwl = zeros((0, 4))
  
          return Npwl, Hpwl, Cpwl, fparm_pwl, any_pwl
docs: Returns the piece-wise linear components of the objective function.