Refereed Journal Publications
    2013
  1. Jack Dongarra, Mathieu Faverge, Thomas Herault, Mathias Jacquelin, Julien Langou, and Yves Robert. Hierarchical QR factorization algorithms for multi-core cluster systems. Parallel Computing, 39(4-5): 212-232. DOI information: 10.1016/j.parco.2013.01.003
  2. Fred G. Gustavson, Jerzy Waśniewski, Jack J. Dongarra, José R. Herrero, and Julien Langou. Level-3 Cholesky factorization routines improve performance of many Cholesky algorithms. ACM Transactions on Mathematical Software, 39(2):9:1--9:10.

    3. 2012
  3. Henri Calandra, Serge Gratton, Julien Langou, Xavier Pinel, and Xavier Vasseur. Flexible Variants of Block Restarted GMRES Methods with Application to Geophysics. SIAM J. Scientific Computing, 34(2):A714--A736, 2012.
  4. James Demmel, Laura Grigori, Mark Hoemmen, and Julien Langou. Communication-Optimal Parallel and Sequential QR and LU Factorizations. SIAM J. Scientific Computing, 34(1):A206--A239, 2012.

    5. 2011
  5. Emmanuel Agullo, Camille Coti, Thomas Herault, Julien Langou, Sylvain Peyronnet, Ala Rezmerita, Franck Cappello, and Jack Dongarra. QCG-OMPI: MPI Applications on Grids. Future Generation Computer Systems, 27(4):357--369, 2011.
  6. Eugene Vecharynski and Julien Langou. Any admissible cycle-convergence behavior is possible for restarted GMRES at its initial cycles. Numerical Linear Algebra with Applications, 18(3):499--511, 2011.

    7. 2010
  7. Fred G. Gustavson, Jerzy Waśniewski, Jack J. Dongarra, and Julien Langou. Rectangular full packed format for Cholesky's algorithm: Factorization, solution and inversion. ACM Trans. Math. Software, 37(2):1-21, 2010.
  8. Eugene Vecharynski and Julien Langou. The cycle-convergence of restarted GMRES for normal matrices is sublinear. SIAM J. Scientific Computing, 32(1):186-196, 2010.

    9. 2009
  9. Marc Baboulin, Alfredo Buttari, Jack Dongarra, Jakub Kurzak, Julie Langou, Julien Langou, Piotr Luszczek, and Stanimire Tomov. Accelerating scientific computations with mixed precision algorithms. Computer Physics Communications, 180:2526-2533, 2009.
  10. Marc Baboulin, Jack Dongarra, Serge Gratton, and Julien Langou. Computing the conditioning of the components of a linear least squares solution. Numerical Linear Algebra and its Applications, 16(7):517-533, 2009.
  11. Jack Dongarra and Julien Langou. The problem with the Linpack benchmark matrix generator. International Journal of High Performance Computing Applications, 23(1):5-13, 2009.
  12. George Bosilca, Rémi Delmas, Jack Dongarra, and Julien Langou. Algorithm-based fault tolerance applied to high performance computing. J. Parallel Distrib. Comput., 69:410-416, 2009.
  13. Alfredo Buttari, Julien Langou, Jakub Kurzak, and Jack Dongarra. A class of parallel tiled linear algebra algorithms for multicore architectures. Parallel Computing, 35:38-53, 2009.
  14. Marc Baboulin, Luc Giraud, Serge Gratton, and Julien Langou. Parallel tools for solving incremental dense least squares problems: application to space geodesy. J. of Algorithms & Computationnal Technology, 3(1):117-133, 2009.

    15. 2008
  15. Alfredo Buttari, Julien Langou, Jakub Kurzak, and Jack Dongarra. Parallel tiled QR factorization for multicore architectures. Concurrency Computat.: Pract. Exper., 20(13):1573-1590, 2008.

    16. 2007
  16. Alfredo Buttari, Jack Dongarra, Julie Langou, Julien Langou, Piotr Luszczek, and Jakub Kurzak. Mixed precision iterative refinement techniques for the solution of dense linear systems. International Journal of High Performance Computing Applications, 21(4):457-466, 2007.
  17. Alfredo Buttari, Victor Eijkhout, Julien Langou, and Salvatore Filippone. Performance optimization and modeling of blocked sparse kernels. International Journal of High Performance Computing Applications, 21(4):467-484, 2007.
  18. Julien Langou, Zizhong Chen, George Bosilca, and Jack Dongarra. Recovery patterns for iterative methods in a parallel unstable environment. SIAM J. Scientific Computing, 30(1):102-116, 2007.
  19. Marc Baboulin, Serge Gratton, Luc Giraud, and Julien Langou. A distributed packed storage for large parallel calculations. Concurrency and Computation: Practice and Experience, 19(4):483-502, 2007.
  20. Luc Giraud, Serge Gratton, and Julien Langou. Convergence in backward error of relaxed GMRES. SIAM J. Scientific Computing, 29(2):710-728, 2007.

    21. 2006
  21. Alicja Smoktunowicz, Jesse L. Barlow, and Julien Langou. A note on the error analysis of classical Gram-Schmidt. Numerische Mathematik, 105(2):299-313, 2006.
  22. Stanimire Tomov, Julien Langou, Jack Dongarra, Andrew Canning, and Lin-Wang Wang. Conjugate-gradient eigenvalue solvers in computing electronic properties of nanostructure architectures. Int. J. Computational Science and Engineering, 2(3/4):205-212, 2006.
  23. Luc Giraud, Julien Langou, and Guillaume Sylvand. On the parallel solution of large industrial wave propagation problems. Journal of Computational Acoustics, 14(1):83-111, 2006.
  24. George Bosilca, Zizhong Chen, Jack Dongarra, Victor Eijkhout, Graham E. Fagg, Erika Fuentes, Julien Langou, Piotr Luszczek, Jelena Pjesivac-Grbovic, Keith Seymour, Haihang You, and Satish S. Vadiyar. Self Adapting Numerical Software (SANS) Effort. IBM Journal of Research and Development, 50(2/3):223-238, 2006.

    25. 2005
  25. Luc Giraud, Julien Langou, and Miroslav Rozložník. On the loss of orthogonality in the Gram-Schmidt orthognalization process. Computers and Mathematics with Applications, 50:1069-1075, 2005.
  26. Luc Giraud, Julien Langou, Miroslav Rozložník, and Jasper van den Eshof. Rounding error analysis of the classical Gram-Schmidt orthogonalization process. Numerische Mathematik, 101(1):87-100, 2005.
  27. Valérie Frayssé, Serge Gratton, Luc Giraud, and Julien Langou. Algorithm 842: A set of GMRES routines for real and complex arithmetics on high performance computers. ACM Trans. Math. Software, 31(2):228-238, 2005.
  28. Iain S. Duff, Luc Giraud, Julien Langou, and Émeric Martin. Using spectral low rank preconditioners for large electromagnetic calculations. Int. J. Numerical Methods in Engineering, 62(3):416-434, 2005.

    29. 2004
  29. Luc Giraud, Serge Gratton, and Julien Langou. A rank-$k$ update procedure for reorthogonalizing the orthogonal factor from modified Gram-Schmidt. SIAM J. Matrix Analysis and Applications, 25(4):1163-1177, 2004.

    30. 2003
  30. Luc Giraud and Julien Langou. A robust criterion for the modified Gram-Schmidt algorithm with selective reorthogonalization. SIAM J. Scientific Computing, 25(2):417-441, 2003.

    31. 2002
  31. Luc Giraud and Julien Langou. When modified Gram-Schmidt generates a well-conditioned set of vectors. IMA J. Numerical Analysis, 22:521-528, 2002.

Paper in Refereed Conference Proceedings
    2012
  1. Jack Dongarra, Mathieu Faverge, Thomas Herault, Julien Langou, and Yves Robert. Hierarchical QR factorization algorithms for multi-core cluster systems. In the Proceedings of IEEE International Parallel & Distributed Processing Symposium 2012 (IPDPS'12), Shanghai, China, May 21-25, 2012. Acceptance Rate: 21% (118/568).

    2. 2011
  2. Henricus Bouwmeester, Mathias Jacquelin, Julien Langou, and Yves Robert. Tiled QR factorization algorithms. In ACM/IEEE SC 2011 Conference (SC'11), Seattle, WA, November 12-18, 2011. Acceptance Rate: 21% (74/352).
  3. Emmanuel Agullo, Cédric Augonnet, Jack Dongarra, Mathieu Faverge, Julien Langou, Hatem Ltaief, and Stanimire Tomov. LU factorization for accelerator-based systems. Best Paper of the Conference. In the 9th ACS/IEEE International Conference on Computer Systems and Applications (AICCSA 11), Sharm El-Sheikh, Egypt, June 27-30, 2011.
  4. George Bosilca, Aurélien Bouteiller, Anthony Danalis, Mathieu Faverge, Azzam Haidar, Thomas Herault, Jakub Kurzak, Julien Langou, Pierre Lemarinier, Hatem Ltaief, Piotr Luszczek, Asim YarKhan, and Jack Dongarra. Flexible development of dense linear algebra algorithms on massively parallel architectures with DPLASMA. In the 12th IEEE International Workshop on Parallel and Distributed Scientific and Engineering Computing (PDSEC-11), Anchorage, Alaska, USA, May 16-20, 2011.

    5. 2010
  5. Emmanuel Agullo, Henricus Bouwmeester, Jack Dongarra, Jakub Kurzak, Julien Langou, and Lee Rosenberg. Towards an efficient tile matrix inversion of symmetric positive definite matrices on multicore architectures. Best Student Paper. In the Proceedings of 9th International Meeting on High Performance Computing for Computational Science (VecPar'10), Berkeley, CA, USA, June 22-25, 2010.
  6. Emmanuel Agullo, Camille Coti, Jack Dongarra, Thomas Herault, and Julien Langou. QR factorization of tall and skinny matrices in a grid computing environment. In the Proceedings of IEEE International Parallel & Distributed Processing Symposium 2010 (IPDPS'10), Atlanta, GA, USA, April 19-23, 2010. Acceptance Rate: 24% (127/527).

    7. 2009
  7. Emmanuel Agullo, Jim Demmel, Jack Dongarra, Bilel Hadri, Jakub Kurzak, Julien Langou, Haitem Ltaief, Piotr Luszczek, and Stanimire Tomov. Numerical linear algebra on emerging architectures: The PLASMA and MAGMA projects. In Journal of Physics: Conference Series 180 012037, (5 pages), 2009.

    8. 2008
  8. Andrew Canning, Jack Dongarra, Julien Langou, Osni Marques, Stanimire Tomov, Christof Vömel, and Lin-Wang Wang. Interior state computation of nano structures. In the Proceedings of workshop on state-of-the-art in scientific and parallel computing (Para08). Springer's Lecture Notes in Computer Science.
  9. Marc Baboulin, Jack Dongarra, Serge Gratton, and Julien Langou. Computing the conditioning of the components of a linear least squares solution. In the Proceedings of VECPAR '08, High Performance Computing for Computational Science, Toulouse, France, June 24-27, 2008.

    10. 2007
  10. Alfredo Buttari, Jack Dongarra, Jakub Kurzak, Julien Langou, Piotr Luszczek, and Stanimire Tomov. The impact of multicore on math software. In the Proceedings of workshop on state-of-the-art in scientific and parallel computing (Para06). Springer's Lecture Notes in Computer Science 4699, pages 1-10, Umeå, Sweden, 2007.
  11. Alfredo Buttari, Julien Langou, Jakub Kurzak, and Jack Dongarra. Parallel tiled QR factorization for multicore architectures. In the Proceedings of PPAM07. Springer's Lecture Notes in Computer Science 4967, pages 639-648, 2008.
  12. James Demmel, Jack Dongarra, Beresford Parlett, William Kahan, Ming Gu, David Bindel, Yozo Hida, Xiaoye Li, Osni Marques, E. Jason Riedy, Christof Voemel, Julien Langou, Piotr Luszczek, Jakub Kurzak, Alfredo Buttari, Julie Langou, and Stanmire Tomov. Prospectus for the next LAPACK and ScaLAPACK libraries. In the Proceedings of workshop on state-of-the-art in scientific and parallel computing (Para06). Springer's Lecture Notes in Computer Science 4699, pages 11-23, Umeå, Sweden, 2007.

    13. 2006
  13. Alex Zunger, Alberto Franceschetti, Gabriel Bester, Wesley B. Jones, Kwiseon Kim, Peter A. Graf, Ling-Wang Wang, Andrew Canning, Osni Marques, Christof Voemel, Jack Dongarra, Julien Langou, and Stanimire Tomov. Predicting the electronic properties of 3D, million-atom semiconductor nanostructure architectures. In Journal of Physics: Conference Series, volume 46, pages 292-298, 2006.
  14. Julie Langou, Julien Langou, Piotr Luszczek, Jakub Kurzak, Alfredo Buttari, and Jack Dongarra. Exploiting the performance of 32 bit floating point arithmetic in obtaining 64 bit accuracy (revisiting iterative refinement for linear systems). In ACM/IEEE SC 2006 Conference (SC'06), page 50, November 2006.

    15. 2005
  15. Julien Langou, George Bosilca, Graham Fagg, and Jack Dongarra. Hash functions for datatype signatures in MPI. In B. Di Martino et al., editor, the Proceedings of EuroPVM/MPI, Springer's Lecture Notes in Computer Science 3666, pages 76-83, Sorrento, Italy, September 2005.
  16. Wesley B. Jones, Gabriel Bester, Andrew Canning, Alberto Franceschetti, Peter A. Graf, Kwiseon Kim, Julien Langou, Lin-Wang Wang, Jack Dongarra, and Alex Zunger. NanoPSE: A nanoscience problem solving environment for atomistic electronic structure of semiconductor nanostructures. In Journal of Physics: Conference Series, volume 16, pages 277-282, 2005.
  17. Zizhong Chen, Graham~E. Fagg, Edgar Gabriel, Julien Langou, Thara Angskun, George Bosilca, and Jack Dongarra. Building fault survivable MPI programs with FT-MPI using diskless-checkpointing. \newblock In {\em the Proceedings of the tenth ACM SIGPLAN symposium on Principles and Practice of Parallel Programming (PPoPP)}, pages 213-223, Chicago, IL, USA, June 2005.
  18. Stanimire Tomov, Julien Langou, Andrew Canning, Lin-Wang Wang, and Jack Dongarra. Comparison of nonlinear conjugate-gradient methods for computing the electronic properties of nanostructure architectures. In Vaidy S. Sunderman, Geert Dick van Albada, Peter M.A. Sloot, and Jack J. Dongarra, editors, the Proceedings of the 5th International Conference on Computational Science (ICCS). Springer's Lecture Notes in Computer Science 3514, Part III, pages 317-235, Atlanta, GA, USA, May 2005. Springer Verlag.

    19. 2003
  19. Guillaume Alléon, Bruno Carpentieri, Iain S. Duff, Luc Giraud, Julien Langou, Émeric Martin, and Guillaume Sylvand. Efficient parallel iterative solvers for the solution of large dense linear systems arising from the boundary element method in electromagnetism. In the Proceedings of the International Conference on Supercomputing in Nuclear Application (SNA), Paris, September 2003.