@article{etna_vol13_pp56-80, author = {Zden\v{e}k Strako\v{s} and Petr Tich\'{y}}, title = {On error estimation in the conjugate gradient method and why it works in finite precision computations}, journal = {Electron. Trans. Numer. Anal.}, volume = {13}, year = {2002}, pages = {56--80}, }