
@TechReport{f:LaBRI::hprr04b,
  author       = "H\'enon, P. and Pellegrini, F. and Ramet, P. and Roman, J.",
  title        = "Etude sur l'applicabilité de méthodes itératives nouvelles aux problèmes du CESTA",
  institution  = "C.E.A. / C.E.S.T.A",
  year         = "2004",
  note         = "Rapport Final",
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::PMAA2004a,
  author =       "H\'enon, P. and Ramet, P. and Roman, J.",
  title =        "A Blockwise Algorithm for Parallel Incomplete Cholesky Factorization",
  booktitle =    "Proceedings of {PMAA}'2004",
  OPTcrossref =  {},
  OPTkey =       {},
  OPTeditor =    {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTseries =    {},
  year =         "2004",
  OPTorganization = {},
  OPTpublisher = {},
  address =      {Marseille, France},
  month =        oct,
  OPTpages =     {},
  OPTnote =      {},
  OPTannote =    {},
  KEYWORDS =     "Sparse",
  ABSTRACT = {
Solving large sparse linear systems by iterative methods has often been quite unsatisfactory when dealing with pratical "industrial" problems. The main difficulty encountered by such methods is their lack of robustness and, generally, the unpredictability and unconsistency of their performance over a wide sample of different problems; certain methods work quite well for certain types of problems but can fail completely on other problems.

Over the past few years, direct methods have made significant progress thanks to either the combinatorial analysis of the Gaussian elimination process and the parallel algorithmic of blockwise solvers optimized for modern parallel supercomputers. Its is now possible to solve practical three-dimensional problems in the order of several millions of equations in a very powerful way with the direct solvers that efficiently use the superscalar effects of modern processors.

However, direct methods may fail to solve very large three-dimensional problems, due to the large amount of memory needed for these cases.

In our work, we consider an approach which, we hope, will bridge the gap  between the two classes of methods. The goal is to provide a method which exploits the parallel blockwise algorithmic used in the framework of the high performance sparse direct solvers for developping robust parallel incomplete factorization based preconditioners for iterative solvers.

The idea is then to define an adaptive blockwise incomplete factorization that is much more accurate (and numerically more robust) than the scalar incomplete factorizations commonly used to precondition iterative solvers. Our approach consists in computing symbolically the block structure of the factors that would have been obtained with a complete factorization, and then deciding to drop off some blocks of this structure according to relevant criterions. Such incomplete factorization can take advantage of the latest breakthroughts in sparse direct methods and therefore be very competitive in CPU time  while avoiding the memory limitation encountered by direct methods. 
By this way, we expect to be able to solve systems in the order of hundred millions of unknowns. 
}
}

@Article{A:LaBRI::HRR07,
  author = 	 {H\'enon, P. and Ramet, P. and Roman, J.},
  title =        "On finding approximate supernodes for an efficient ILU(k) factorization",
  journal = 	 {{P}arallel {C}omputing},
  year = 	 {2008},
  OPTkey = 	 {},
  volume = 	 {34},
  number = 	 {},
  pages = 	 {345--362},
  month = 	 {},
  OPTnote = 	 {},
  OPTannote = 	 {},
  KEYWORDS =     "Sparse",
  ABSTRACT =  {Among existing preconditioners, the level-of-fill ILU has been quite popular as a general-purpose technique. Experimental observations have shown that, when coupled with block techniques, these methods can be quite effective in solving realistic problems arising from various applications. In this work, we consider an extension of this kind of method which is suitable for parallel environments. Our method is developed from the framework of high performance sparse direct solvers. The main idea we propose is to define an adaptive blockwise incomplete factorization that is much more accurate (and numerically more robust) than the scalar incomplete factorizations commonly used to precondition iterative solvers. These requirements lead to a robust class of parallel preconditioners based on generalized versions of block ILU techniques.}
}

@InProceedings{C:LaBRI::PMAA2006a,
  author =       "H\'enon, P. and Ramet, P. and Roman, J.",
  title =        "On finding approximate supernodes for an efficient ILU(k) factorization",
  booktitle =    "Proceedings of {PMAA}'2006",
  OPTcrossref =  {},
  OPTkey =       {},
  OPTeditor =    {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTseries =    {},
  year =         "2006",
  OPTorganization = {},
  OPTpublisher = {},
  address =      {Rennes, France},
  month =        sep,
  OPTpages =     {},
  OPTnote =      {},
  OPTannote =    {},
  URL = {http://www.labri.fr/~ramet/restricted/pmaa06a.pdf},
  KEYWORDS =     "Sparse",
  OPTABSTRACT = {}
}

@InProceedings{C:LaBRI::sparsedays2003,
  author = 	 {H\'enon, P. and Pellegrini, F. and Ramet, P. and Roman, J.},
  title = 	 {An efficient hybrid MPI/Thread implementation on a network of SMP nodes for the parallel sparse direct solver PaStix: ordering / scheduling / memory managment / out-of-core issues, and application to preconditioning},
  booktitle = {Sparse Days},
  OPTcrossref =  {},
  OPTkey = 	 {},
  OPTpages = 	 {},
  year = 	 {2003},
  OPTeditor = 	 {},
  OPTvolume = 	 {},
  OPTnumber = 	 {},
  OPTseries = 	 {},
  address = 	 {Saint Girons, France},
  month = 	 jun,
  OPTorganization = {},
  OPTpublisher = {},
  OPTnote = 	 {},
  OPTannote = 	 {},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::SC2004,
  author = "H\'enon, P. and Ramet, P. and Roman, J.",
  title = "{P}arallel {C}omplete and {I}ncomplete {B}lockwise {F}actorisations for {V}ery {L}arge {S}parse {S}ystems",
  booktitle = "{SuperComputing}'2004",
  OPTcrossref = {},
  OPTkey = {},
  OPTeditor = {},
  OPTvolume = {},
  OPTnumber = {},
  OPTseries = {},
  year = "2004",
  OPTorganization = {},
  OPTpublisher = {},
  address = {Pittsburgh, USA},
  month = nov,
  OPTpages = {},
  OPTnote = {},
  OPTannote = {},
  URL = {http://www.labri.fr/~ramet/restricted/poster_sc2004.tar},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::SC2010,
  author = "H\'enon, P. and Ramet, P.",
  title = "Scalable direct and iterative solvers",
  booktitle = "{SuperComputing}'2010",
  OPTcrossref = {},
  OPTkey = {},
  OPTeditor = {},
  OPTvolume = {},
  OPTnumber = {},
  OPTseries = {},
  year = "2010",
  OPTorganization = {},
  OPTpublisher = {},
  address = {New Orleans, USA},
  month = nov,
  OPTpages = {},
  OPTnote = {},
  OPTannote = {},
  OPTURL = {http://www.labri.fr/~ramet/restricted/poster_sc2010.tar},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::pre03,
  author = 	 {H\'enon, P. and Pellegrini, F. and Ramet, P. and Roman, J.},
  title = 	 {Towards High Performance Hybrid Direct-Iterative Solvers for Large Sparse Systems},
  booktitle = {International SIAM Conference On Preconditioning Techniques For Large Sparse Matrix Problems In Scientific And Industrial Applications},
  OPTcrossref =  {},
  OPTkey = 	 {},
  OPTpages = 	 {},
  year = 	 {2003},
  OPTeditor = 	 {},
  OPTvolume = 	 {},
  OPTnumber = 	 {},
  OPTseries = 	 {},
  address = 	 {Napa Valley, USA},
  month = 	 oct,
  OPTorganization = {},
  OPTpublisher = {},
  OPTnote = 	 {},
  OPTannote = 	 {},
  URL = {http://www.labri.fr/~ramet/restricted/pred2003.ps},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::pre05,
  author = 	 {H\'enon, P. and Pellegrini, F. and Ramet, P. and Roman, J.},
  title = 	 {Blocking Issues for an Efficient Parallel Block ILU Preconditioner},
  booktitle = {International SIAM Conference On Preconditioning Techniques For Large Sparse Matrix Problems In Scientific And Industrial Applications},
  OPTcrossref =  {},
  OPTkey = 	 {},
  OPTpages = 	 {},
  year = 	 {2005},
  OPTeditor = 	 {},
  OPTvolume = 	 {},
  OPTnumber = 	 {},
  OPTseries = 	 {},
  address = 	 {Atlanta, USA},
  month = 	 may,
  OPTorganization = {},
  OPTpublisher = {},
  OPTnote = 	 {},
  OPTannote = 	 {},
  URL = {http://www.labri.fr/~ramet/restricted/pred2005.ps},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::ppsc2004a,
  author = 	 {H\'enon, P. and Pellegrini, F. and Ramet, P. and Roman, J. and Saad, Y.},
  title = 	 {High Performance Complete and Incomplete Factorizations for Very Large Sparse Systems by using {Scotch} and {PaStiX} softwares},
  booktitle = {Eleventh {SIAM} Conference on Parallel Processing for Scientific Computing},
  OPTcrossref =  {},
  OPTkey = 	 {},
  OPTpages = 	 {},
  year = 	 {2004},
  OPTeditor = 	 {},
  OPTvolume = 	 {},
  OPTnumber = 	 {},
  OPTseries = 	 {},
  address = 	 {San Francisco, USA},
  month = 	 feb,
  OPTorganization = {},
  OPTpublisher = {},
  OPTnote = 	 {},
  OPTannote = 	 {},
  KEYWORDS =     "Sparse",
  ABSTRACT = 
{
PaStiX is a scientific library that provides a high performance direct supernodal solver for very large sparse linear systems. It relies on a block factorization based on an hybrid ordering (Nested Dissection + Halo Approximate Minimum Degree) obtained using the Scotch library. Efficient static scheduling and memory management are used to solve irregular problems with more of 25 millions unknowns on clusters of SMP nodes.
In order to solve larger 3D problems, we apply these blockwise algorithms to compute robust and efficient parallel ILU preconditioners.
}
}

@InProceedings{C:LaBRI::para2004,
  author = 	 {H\'enon, P. and Pellegrini, F. and Ramet, P. and Roman, J. and Saad, Y.},
  title = 	 {Applying parallel direct solver skills to build robust and highly performant preconditioners},
  booktitle = {Proceedings of {PARA'2004}},
  OPTcrossref =  {},
  OPTkey = 	 {},
  pages = 	 {601--619},
  year = 	 {2004},
  OPTeditor = 	 {},
  volume = 	 {3732},
  OPTnumber = 	 {},
  series = 	 {LNCS},
  address = 	 {Copenhagen, Denmark},
  month = 	 jun,
  OPTorganization = {},
  publisher =    "Springer Verlag",
  OPTnote = 	 {},
  OPTannote = 	 {},
  URL = {http://www.labri.fr/~ramet/restricted/para2004.pdf},
  ABSTRACT = {The purpose of our work is to provide a method which exploits the parallel blockwise algorithmic approach used in the framework of high performance sparse direct solvers in order to develop robust preconditioners based on a parallel incomplete factorization. The idea is then to define an adaptive blockwise incomplete factorization that is much more accurate (and numerically more robust) than the scalar incomplete factorizations commonly used to precondition iterative solvers.},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::para2006,
  author = 	 {H\'enon, P. and Ramet, P. and Roman, J. },
  title = 	 {Partitioning and Blocking Issues for a Parallel Incomplete Factorization},
  booktitle = {Proceedings of {PARA'2006}},
  OPTcrossref =  {},
  OPTkey = 	 {},
  pages = 	 {929--937},
  year = 	 {2006},
  OPTeditor = 	 {},
  volume = 	 {4699},
  OPTnumber = 	 {},
  series = 	 {LNCS},
  address = 	 {Umea, Sweden},
  month = 	 jun,
  OPTorganization = {},
  publisher =    "Springer Verlag",
  OPTnote = 	 {},
  OPTannote = 	 {},
  URL = {http://www.labri.fr/~ramet/restricted/para2006.pdf},
  ABSTRACT = {The purpose of this work is to provide a method which exploits the parallel block-wise algorithmic approach used in the framework of high performance sparse direct solvers in order to develop robust and efficient preconditioners based on a parallel incomplete factorization.},
  KEYWORDS =     "Sparse"
}

@InProceedings{C:LaBRI::REDIMSOPS,
  author =       "Ramet, P.",
  title =        "High performances methods for solving large sparse linear systems - Direct and Incomplete Factorization",
  booktitle =    "Second NExt Grid Systems and Techniques, REDIMSPS Workshop",
  OPTcrossref =  {},
  OPTkey =       {},
  OPTeditor =    {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTseries =    {},
  year =         "2007",
  OPTorganization = {},
  OPTpublisher = {},
  address =      {Tokyo, Japan},
  month =        may,
  OPTpages =     {},
  OPTnote =      {},
  OPTannote =    {},
  OPTURL = {},
  KEYWORDS =     "Sparse",
  OPTABSTRACT = {}
}

@Misc{C:LaBRI::UUIC,
  author =       "H\'enon, P. and Ramet, P.",
  title =        "Scalable direct and iterative solvers",
  note =    "Workshop INRIA-UUIC, Bordeaux, France",
  OPTcrossref =  {},
  OPTkey =       {},
  OPTeditor =    {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTseries =    {},
  year =         "2010",
  OPTorganization = {},
  OPTpublisher = {},
  address =      {Bordeaux, France},
  month =        jun,
  OPTpages =     {},
  OPTnote =      {},
  OPTannote =    {},
  OPTURL = {},
  KEYWORDS =     "Sparse",
  OPTABSTRACT = {}
}

@InProceedings{C:LaBRI::PPAM07,
  author =       "H\'enon, P. and Ramet, P. and Roman, J.",
  title =        "A supernode amalgamation algorithm for an efficient block incomplete factorization",
  booktitle =    "Proceedings of {PPAM}'2007, CTPSM07 Workshop",
  OPTcrossref =  {},
  OPTkey =       {},
  OPTeditor =    {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTseries =    {},
  year =         "2007",
  OPTorganization = {},
  OPTpublisher = {},
  address =      {Gdansk, Poland},
  month =        sep,
  OPTpages =     {},
  OPTnote =      {},
  OPTannote =    {},
  URL = {http://www.labri.fr/~ramet/restricted/ppam07.pdf},
  KEYWORDS =     "Sparse",
  OPTABSTRACT = {}
}

@Misc{C:LaBRI::MN08,
  author =       "H\'enon, P. and Ramet, P. and Roman, J.",
  title =        "A supernode amalgamation algorithm for an efficient block incomplete factorization",
  note =    "Mini-Workshop on parallel iterative solvers and domain decomposition techniques, Minneapolis, USA",
  OPTcrossref =  {},
  OPTkey =       {},
  OPTeditor =    {},
  OPTvolume =    {},
  OPTnumber =    {},
  OPTseries =    {},
  year =         "2008",
  OPTorganization = {},
  OPTpublisher = {},
  address =      {Minneapolis, USA},
  month =        jul,
  OPTpages =     {},
  OPTnote =      {},
  OPTannote =    {},
  KEYWORDS =     "Sparse",
  OPTABSTRACT = {}
}