Hussam Al Daas

Hussam Al Daas

PhD in Applied Mathematics and HPC

I started my PhD in 2015 on the subject Communication reducing iterative methods for the solution of linear systems arising from the reservoirs simulation under the supervision of Laura Grigori at ALPINES team at INRIA-Paris and LJLL at UPMC with collaboration with TOTAL EP at Pau (coordination with Pascal Hénon).

Research items

  • High performance computing
  • Numerical linear algebra
  • Krylov subspace methods
  • Low-rank approximation methods
  • Domain decomposition methods


  • 3- H. Al Daas, L. Grigori, P. Hénon, Ph. Ricoux, Recycling Krylov subspaces and reducing deflation subspaces for solving sequence of linear systems, PDF, submitted to ACM TOMS
  • 2- H. Al Daas, L. Grigori, A Class of Efficient Locally Constructed Preconditioners Based on Coarse Spaces, Journal link, PDF (old version), accepted in SIAM Journal on Matrix Analysis and Applications
  • 1- H. Al Daas, L. Grigori, P. Hénon, Ph. Ricoux, Enlarged GMRES for solving linear systems with one or multiple right-hand sides Journal link, PDF (old version), accepted in IMA Journal

Selected talks

Efficient algebraic coarse spaces, Sparse Days, Toulouse, France Sept. 2018
Deflation subspaces and GMRES for solving a sequence of linear systems, PMAA18, Zurich, Switzerland June. 2018
Enlarged GMRES for reducing communication, SIAM PP18, MS 28, Tokyo, Japan Mar. 2018
Krylov subspace methods and deflation strategies, Junior Seminar at INRIA- Paris, France Dec. 2017
Enlarged GMRES for a sequence of linear systems, MATHIAS18, Paris, France Oct. 2017
Enlarged GMRES, SIAM CSE17, MS254, Atlanta, USA Jun. 2017
GMRES based on enlarged Krylov subspaces, SIAM PP16, MS12, Paris, France Apr. 2016

Research stays

CSTJF, centre scientifique TOTAL, Pau, collaboration with Pascal Hénon Jan.-Feb. 2018
CEMRACS, CIRM, Marseille, 6-week summer school Jul.-Aug. 2016
University of California, Berkeley, BeBOP group. Five-month visit in James Demmel’s research group Jan.-May 2016


  • Journal(s)
  • Conference(s)
    • PASC


  • Main contributor
    • CPaLAMeM, C Parallel Linear Algebra Memory Management in PreAlps package (several linear solvers and preconditioners)
  • Only contributor
    • EGMRES, GMRES-MDR and Block GMRES-MDR, C-MPI implementation of enlarged GMRES with deflated restarting, GMRES with Modified Deflated Restart, and Block GMRES-MDR with different variants of deflation strategies


  • 2017 Calculus, Introduction to Analysis for first year students in Physics, 38.5h. Teaching Assistant, UPMC
  • 2015 Numerical analysis, Scientific computation for third year students in Finance, 18h. Teaching Assistant, ENSAE

Work Address

2, rue Simone Iff 75012 Paris, France

Phone Number

+ 33 1 80 49 42 72


Laura Grigori laura(dot)grigori(at)inria(dot)fr
Pascal Hénon pascal(dot)henon(at)total(dot)com