Short bio

I prepared my Ph.D. at Inria-Paris and Sorbonne University (Paris — VI). It was funded by TOTAL S.A. From January 2019 to July 2020 I was a Max Planck Society postdoctoral research fellow in the NLMA team in the CSC group. Starting from August 2020, I hold a research position at the Computational Mathematics Group, STFC, UKRI.


Research items

  • High performance computing
  • Numerical linear algebra
  • Tensor methods
  • Krylov subspace methods
  • Domain decomposition methods


  • P. Goyal, H. Al Daas, P. Benner, Low-Rank and Total Variation Regularization and Its Application to Image Recovery, PDF, 2020.
  • H. Al Daas, L. Grigori, P. Jolivet, P. H. Tournier, A Multilevel Schwarz Preconditioner Based on a Hierarchy of Robust Coarse Spaces, PDF 2019, bibtex, code for reproducing the results available here, PETSc interface through the HPDDM package, PCHPDDM.
  • H. Al Daas, L. Grigori, P. Henon, P. Ricoux, Recycling Krylov Subspaces and Truncating Deflation Subspaces for Solving Sequence of Linear Systems, PDF, 2018, bibtex.


  • H. Al Daas, Solving linear systems arising from reservoirs modeling, Ph.D. thesis, PDF, bibtex
  • 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
  • H. Al Daas, L. Grigori, P. Hénon, Ph. Ricoux, Enlarged GMRES for solving linear systems with one or multiple right-hand sides Journal link, accepted in IMA Journal

Selected talks

  • Communication-avoiding orthogonalization algorithm for tensor trains, GAMM ANLA 2019, Chemnitz, Germany
  • Efficient algebraic coarse spaces, Sparse Days 2018, Toulouse, France
  • Deflation subspaces and GMRES for solving a sequence of linear systems, PMAA18, Zurich, Switzerland
  • Enlarged GMRES for reducing communication, SIAM PP18, MS 28, Tokyo, Japan
  • Krylov subspace methods and deflation strategies, Junior Seminar at INRIA- Paris, France
  • Enlarged GMRES for a sequence of linear systems, MATHIAS18, Paris, France
  • Enlarged GMRES, SIAM CSE17, MS254, Atlanta, USA
  • GMRES based on enlarged Krylov subspaces, SIAM PP16, MS12, Paris, France

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
    • EuroPar


  • Co-developer
    • CPaLAMeM: C Parallel Linear Algebra Memory Management in PreAlps package (several linear solvers and preconditioners)
  • Developer
    • cTT, pcTT: C and C-MPI implementation of TT tensor arithmetic operations
    • 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


  • 2019 Numerical Linear Algebra, Bachelor level. Teaching Assistant, Otto von Guericke University, Magdeburg, Germany
  • 2017 Calculus, Introduction to Analysis for first year students. Teaching Assistant, UPMC, Paris, France
  • 2015 Numerical analysis, Scientific computation for third year students. Teaching Assistant, ENSAE, Paris, France