@article{etna_vol40_pp338-355, author = {Serge Gratton and Pavel Jir\'anek and Xavier Vasseur}, title = {Energy backward error: interpretation in numerical solution of elliptic partial differential equations and behaviour in the conjugate gradient method}, journal = {Electron. Trans. Numer. Anal.}, volume = {40}, year = {2013}, pages = {338--355}, }