@TechReport{      Shewchuk_1994aa,
  address       = {Pittsburgh, PA, USA},
  author        = {Shewchuk, Jonathan R.},
  file          = {Shewchuk_1994aa.pdf},
  institution   = {Carnegie Mellon University},
  keywords      = {cg,pcg,linear-systems},
  langid        = {english},
  title         = {An Introduction to the Conjugate Gradient Method Without the Agonizing Pain},
  year          = {1994}
}