APO Team

Head : Serge GRATTON

The APO team (Parallel Algorithms and optimization) works mainly along the following 5 axes:

  • new methods for solving large linear systems and their applications to simulation
  • optimal control and its applications to the design of optimal trajectories
  • global optimization
  • mathematical and computational aspects of artificial intelligence and  processing of large data sets
  • optimization for large problems and data assimilation

The team is also strongly involved in the LabEx CIMI (Laboratory of Excellence). A joint team exists between IRIT and IMT. This is the CASI team focused on scientific computation and numerical simulation.

Since 2014, the APO team and the ALGO team at Cerfacs have also set up a joint laboratory. The objective of this common laboratory is to analyse  and implement  methods to solve problems of interest to Cerfacs, IRIT and their partners. The joint laboratory currently consists of some 20 people, including eight permanent staff from both institutions.

The team is also involved in the 3IA ANITI Institute (Toulouse Artificial and Natural Institute). This project is centred on the  introduction of physical constraints into machine learning algorithms and exploring the associated high-performance computing issues.

Background: The team was created and coordinated by Joseph Noailles. It was then administered by Patrick Amestoy.


Numerical linear algebra
Optimization and control
Machine Learning
Data assimilation
High Performance Computing (HPC)

Members team

Permanent members
Non-permanent members

publications team

International journals articles
  • Daniele Antonio Di Pietro, Frank Hülsemann, Pierre Matalon, Paul Mycek, Ulrich Rüde, Daniel Ruiz

    An h-multigrid method for Hybrid High-Order discretizations

    SIAM Journal on Scientific Computing, Society for Industrial and Applied Mathematics, 2021, pp.S839-S861. ⟨10.1137/20M1342471⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02434411v3

  • Alfredo Buttari, Markus Huber, Philippe Leleux, Théo Mary, Ulrich Ruede, Barbara Wohlmuth

    Block Low Rank Single Precision Coarse Grid Solvers for Extreme Scale Multigrid Methods

    Numerical Linear Algebra with Applications, Wiley, 2021

    Accès: https://hal.archives-ouvertes.fr/hal-02528532

  • Pierre Jolivet, Mohd Afeef Badri, Y. Favennec

    Deterministic radiative transfer equation solver on unstructured tetrahedral meshes: Efficient assembly and preconditioning

    Journal of Computational Physics, Elsevier, 2021, 437, pp.110313. ⟨10.1016/j.jcp.2021.110313⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03196806

  • Hussam Al Daas, Laura Grigori, Pierre Jolivet, Pierre-Henri Tournier

    A Multilevel Schwarz Preconditioner Based on a Hierarchy of Robust Coarse Spaces

    SIAM Journal on Scientific Computing, Society for Industrial and Applied Mathematics, 2021, 43 (3), pp.A1907-A1928. ⟨10.1137/19M1266964⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02151184v2

  • Florian Feppon, Grégoire Allaire, Charles Dapogny, Pierre Jolivet

    Body-fitted topology optimization of 2D and 3D fluid-to-fluid heat exchangers

    Computer Methods in Applied Mechanics and Engineering, Elsevier, 2021, 376, pp.113638. ⟨10.1016/j.cma.2020.113638⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02924308v2

  • Bernard Bonnard, Olivier Cots, Boris Wembe

    A Zermelo navigation problem with a vortex singularity

    ESAIM: Control, Optimisation and Calculus of Variations, EDP Sciences, 2021, 27 (S), pp.S10. ⟨10.1051/cocv/2020058⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02296046v3

  • Antoine Bernigaud, Serge Gratton, Flavia Lenti, Ehouarn Simon, Oumaima Sohab

    Lp‐norm regularization approaches in variational data assimilation

    Quarterly Journal of the Royal Meteorological Society, Wiley, 2021, 147, pp.2067 – 2081. ⟨10.1002/qj.4010⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03160275

  • Daniele Di Pietro, Frank Hülsemann, Pierre Matalon, Paul Mycek, Ulrich Rüde, Daniel Ruiz

    Towards robust, fast solutions of elliptic equations on complex domains through HHO discretizations and non-nested multigrid methods

    International Journal for Numerical Methods in Engineering, Wiley, In press, ⟨10.1002/nme.6803⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03163476v2

  • Annalisa Paroni, Nathalie Henrich Bernardoni, Christophe Savariaux, Hélène Loevenbruck, Pascale Calabrese, Thomas Pellegrini, Sandrine Mouysset, Silvain Gerber

    Vocal drum sounds in human beatboxing: An acoustic and articulatory exploration using electromagnetic articulography

    Journal of the Acoustical Society of America, Acoustical Society of America, 2021, 149 (1), pp.191-206. ⟨10.1121/10.0002921⟩

    Accès: https://hal.univ-grenoble-alpes.fr/hal-03107358

  • Serge Gratton, Ehouarn Simon, David Titley-Peloquin, Philippe Toint

    Minimizing convex quadratics with variable precision conjugate gradients

    Numerical Linear Algebra with Applications, Wiley, 2021, 28 (e2337)

    Accès: https://hal.archives-ouvertes.fr/hal-02959082

  • National journals articles
    Special issues of journal
    International conferences articles
  • Justin Loye, Sandrine Mouysset, Katia Jaffrès-Runser

    Mesure de l’influence d’une pandémie sur l’écosystème de peering Internet

    23èmes Rencontres Francophones sur les Aspects Algorithmiques des Télécommunications (AlgoTel 2021), Université de La Rochelle, May 2021, La Rochelle, France

    Accès: https://hal.archives-ouvertes.fr/hal-03211336

  • Victorita Dolean, Pierre Jolivet, Stéphane Operto, Pierre-Henri Tournier

    Large-scale frequency-domain seismic wave modeling on h-adaptive tetrahedral meshes with iterative solver and multi-level domain-decomposition preconditioners

    SEG 2020 – Annual Meeting of the Society of Exploration Geophysicists, Society of Exploration Geophysicists, Oct 2020, Houston, United States. pp.1949-4645, ⟨10.1190/segam2020-3427414.1⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03136868

  • Térence Bayen, Olivier Cots

    Tangency property and prior-saturation points in planar minimal time problems

    International Federation of Automatic Control 2020 (IFAC 2020), Jul 2020, Berlin, Germany

    Accès: https://hal-univ-avignon.archives-ouvertes.fr/hal-02926508

  • Luce Le Gorrec, Sandrine Mouysset, Iain Duff, Philip Knight, Daniel Ruiz

    Uncovering Hidden Block Structure for Clustering

    European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases – ECML PKDD 2019, Sep 2019, Würzburg, Germany. pp.140-155, ⟨10.1007/978-3-030-46150-8_9⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03003811

  • Sandrine Mouysset, Jérôme Ermont, Jean-Luc Scharbarg

    Limiting over sampling to improve transmission schedulability in a mixed NoC/AFDX architecture

    24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2019), Sep 2019, Zaragoza, Spain. ⟨10.1109/ETFA.2019.8869037⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02961985

  • Iain Duff, Philippe Leleux, Daniel Ruiz, F Torun

    Improving the scalability of the ABCD Solver with a combination of new load balancing and communication minimization techniques

    Parco 2019: Parallel Computing Conference, Sep 2019, Prague, Czech Republic. ⟨10.3233/APC200052⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02893783

  • Luce Le Gorrec, Sandrine Mouysset, Daniel Ruiz

    Doubly-stochastic scaling of adjacency matrices for community detection (5th International Conference on Computational Social Science)

    5th International Conference on Computational Social Science – IC2S2 2019, Jul 2019, Amsterdam, Netherlands

    Accès: https://hal.archives-ouvertes.fr/hal-03003813

  • Ghina Abdallah, Jérôme Ermont, Sandrine Mouysset, Jean-Luc Scharbarg

    Towards a generic platform for the distribution of avionics applications on manycores

    Work-in-Progress Session of 31st ECRTS 2019, Jul 2019, Stuttgart, Germany. pp.4-6

    Accès: https://hal.archives-ouvertes.fr/hal-02965528

  • Sandrine Mouysset, Ronan Guivarch

    ParKerC: Toolbox for Parallel Kernel Clustering Methods

    10th International Conference on Pattern Recognition Systems – ICPRS 2019, Jul 2019, Tours, France. ⟨10.1049/cp.2019.0253⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03003819

  • Luce Le Gorrec, Sandrine Mouysset, Daniel Ruiz, Philip A. Knight, Iain S. Duff

    Détection automatique de structures blocs sur des matrices

    21ème Conférence sur l’Apprentissage Automatique (CAp 2019), AFIA : Association française pour l’intelligence artificielle, Jul 2019, Toulouse, France. pp.99-108

    Accès: https://hal.archives-ouvertes.fr/hal-03003812

  • National conferences articles
  • M.A. Badri, Yann Favennec, Pierre Jolivet, Steven Le Corre, Arnaud Biallais, Benoit Rousseau

    Discrete-scale numerical radiative transfer analysis of porous participating media

    14èmes Journées d”Etudes des Milieux Poreux – JEMP 2018, Oct 2018, Nantes, France

    Accès: http://hal.univ-nantes.fr/hal-02386888

  • Conferences articles without published proceedings
  • Carlos Balsa, Michel Daydé, José Palma, Daniel Ruiz

    Inexact Subspace Iteration for the Consecutive Solution of Linear Systems with Changing Right-Hand Sides

    Pinto; A.A. and Zilberman; D. DGS 2016, BIOECONOMY 2015: Modeling, Dynamics, Optimization and Bioeconomics III, 224, Springer International Publishing, pp.49–78, 2018, Springer PROMS : Proceedings in Mathematics & Statistics, 978-3-319-74085-0. ⟨10.1007/978-3-319-74086-7_3⟩

    Accès: https://hal.archives-ouvertes.fr/hal-02982557

  • Serge Gratton, Selime Gurol, Ehouarn Simon, Philippe Toint

    Issues in making the weakly-constrained 4DVar formulation computationally efficient

    Griewank, Andreas; Reich, Sebastian; Roulstone, Ian; Stuart, Andrew. Mathematical and Algorithmic Aspects of Data Assimilation in the Geosciences, 13 (4), Mathematisches Forschungsinstitut Oberwolfach, pp.2705-2748, 2017, Oberwolfach Reports, ISSN: 1660-8933. ⟨10.4171/OWR/2016/47⟩

    Accès: https://hal.archives-ouvertes.fr/hal-03176447

  • Michel Daydé, Denis Veynante

    Les grands sites de calcul et de stockage

    Bouzeghoub, Mokrane; Mosseri, Rémy. Les Big Data à découvert, 2, CNRS, pp.80–81, 2017, 978-2271114648

    Accès: https://hal.archives-ouvertes.fr/hal-03109268

  • Books Books parts
    Thesis and HDR
  • Luce Le Gorrec

    Équilibrage bi-stochastique des matrices pour la détection de structures par blocs et applications

    Réseaux et télécommunications [cs.NI]. Université Paul Sabatier – Toulouse III, 2019. Français. ⟨NNT : 2019TOU30136⟩

    Accès: https://tel.archives-ouvertes.fr/tel-02735291

  • Franklin Delehelle

    ASGART-fast & efficient de novo mapping of segmental duplications at the genome scale

    Quantitative Methods [q-bio.QM]. INSA de Toulouse, 2019. English. ⟨NNT : 2019ISAT0020⟩

    Accès: https://tel.archives-ouvertes.fr/tel-02497362

  • Alfredo Buttari

    Scalability of parallel sparse direct solvers: methods, memory and performance

    Distributed, Parallel, and Cluster Computing [cs.DC]. Toulouse INP, 2018

    Accès: https://hal.archives-ouvertes.fr/tel-01913033

  • Thesis and HDR
  • Luce Le Gorrec, Sandrine Mouysset, Stergos Afantenos

    Identification des actes de dialogue d’un réseau BiLSTM à l’aide de méthodes de clustering

    [Rapport de recherche] IRIT : Institut en Recherche Informatique de Toulouse, France. 2019

    Accès: https://hal.archives-ouvertes.fr/hal-03003810

  • Patrick Amestoy, Sebastien de la Kethulle de Ryhove, Jean-Yves l’Excellent, Gilles Moreau, Daniil Shantsev

    Efficient use of sparsity by direct solvers applied to 3D controlled-source EM problems

    [Research Report] RR-9220, Inria Grenoble Rhône-Alpes; LIP – ENS Lyon. 2018, pp.26

    Accès: https://hal.inria.fr/hal-01912713

  • Sandrine Mouysset, Ronan Guivarch

    ParKerC: Toolbox for Parallel Kernel Clustering Methods

    [Rapport de recherche] IRIT : Institut en Recherche Informatique de Toulouse, France. 2018

    Accès: https://hal.archives-ouvertes.fr/hal-03034005

  • Luce Le Gorrec, Sandrine Mouysset, Daniel Ruiz

    Evaluation de la qualité des découpages en communautés dans le cas de graphes non orientés pondérés

    [Rapport de recherche] IRIT. 2018

    Accès: https://hal.archives-ouvertes.fr/hal-03033988

  • Iain Duff, Philip Knight, Luce Le Gorrec, Sandrine Mouysset, Daniel Ruiz

    Uncovering hidden block structure for clustering

    [Research Report] IRIT. 2018

    Accès: https://hal.archives-ouvertes.fr/hal-03044269

  • Patrick Amestoy, Jean-Yves l’Excellent, Gilles Moreau

    On Exploiting Sparsity of Multiple Right-Hand Sides in Sparse Direct Solvers

    [Research Report] RR-9122, ENS de Lyon; INRIA Grenoble – Rhone-Alpes. 2017, pp.1-28

    Accès: https://hal.inria.fr/hal-01649244v2

  • Emmanuel Agullo, Alfredo Buttari, Mikko Byckling, Abdou Guermouche, Ian Masliah

    Achieving high-performance with a sparse direct solver on Intel KNL

    [Research Report] RR-9035, Inria Bordeaux Sud-Ouest; CNRS-IRIT; Intel corporation; Université Bordeaux. 2017, pp.15

    Accès: https://hal.inria.fr/hal-01473475

  • Reports

    Contracts team

    AcronymeTitreResp. scDébut – fin
    2020-058 Labex CIMI Michel DAYDé
    2010 – 2025
    SOLHARIS anr Solveurs pour architectures hétérogènes utilisant des supports d’exécution, objectif scalabilité Alfredo BUTTARI
    2019 – 2023
    FSAT 4 HHO
    [Contract completed]
    anr Solveurs rapides pour des discrétisations robustes en mécanique des fluides Daniel RUIZ
    2017 – 2021
    [Contract completed]
    autre Solveurs pour architectures hétérogènes utilisant des supports d’exécution Alfredo BUTTARI
    2013 – 2017
    [Contract completed]
    Méthodes Asynchrones pour la Combustion et les Plasmas Atmosphériques Daniel RUIZ
    2012 – 2015
    [Contract completed]
    Modélisation numérique de systèmes couplés fluide structure multi-échelles: méthodes hybrides avancées pour la réduction des incertitudes sur les limites de stabilité et l’optimisation de la fiabilité des barrières de sureté nucléaire Daniel RUIZ
    2011 – 2015
    [Contract completed]
    autre Environnement et programmation pour le calcul post PETAFLOP Alfredo BUTTARI
    2010 – 2013
    [Contract completed]
    autre Gestion de ressources coopérative multi-niveaux Ronan GUIVARCH
    2009 – 2012
    AcronymeTitreResp. scDébut – fin
    EoCoE-II auropa Energy Oriented Center of Excellence : toward exascale for energy Alfredo BUTTARI
    2019 – 2021
    [Contract completed]
    Integrating Armenia Into ERA : Information and Communication technologies Michel DAYDé
    2012 – 2015
    [Contract completed]
    autre Massively Parallel Computations of Combustion and Emission Simulations Patrick AMESTOY
    2008 – 2012
    AcronymeTitreResp. scDébut – fin
    INTRACI – partie région
    [Contract completed]
    Evaluation des biomarqueurs de la résolution de l’inflammation chez les patients dans des contextes inflammatoires à éthiologie variée et analyse par approche non supervisée des systèmes dynamiques Sandrine MOUYSSET
    2017 – 2020
    Wednesday 3 February 2021, 10h00
    Hybrid direct and iterative solvers for sparse indefinite and overdetermined systems on future exascale architectures
    Philippe LELEUX – Team APO, IRIT INP-ENSEEIHT, En visioconférence
    Tuesday 12 January 2021, 14h30
    Adaptive refinement of the data assimilation process by Kalman ensemble methods for non-linear problems
    Dimitri MOTTET – Team APO, IRIT INP-ENSEEIHT, En visioconférence
    Monday 9 November 2020, 14h00
    Estimation of 3D pose from inaccurate and incomplete data: application to human operators’ activity analysis in a sorting center
    Thibault BLANC BEYNE – Team REVA, IRIT INP-ENSEEIHT, En visioconférence
    Monday 28 October 2019, 14h00
    Bi-Stochastic Scaling of Matrices for Block Structure Detection and Applications
    Luce LE GORREC – Team APO, IRIT INP-ENSEEIHT, Salle des thèses
    Thursday 6 June 2019, 10h30
    ASGART — Cartographie de novo des duplications segmentaires à l’échelle génomique
    Franklin DELEHELLE – Team REVA, Team APO, IRIT 37 allées Jules Guesde, Toulouse
    Friday 24 November 2017, 9h30
    Block Low-Rank multifrontal solvers: complexity, performance, and scalability
    Théo MARY – Team APO – IRIT INP-ENSEEIHT, Salle des thèses
    Wednesday 14 June 2017, 10h00
    Contrôle optimal géométrique et méthodes numériques: application au problème de montée d’un avion
    Damien GOUBINAT – Team APO – IRIT INP-ENSEEIHT, Salle des thèses
    Friday 4 November 2016, 14h00
    Derivative-Free Optimization Methods based on Probabilistic and Deterministic Properties: Complexity Analysis and Numerical Relevance
    Clément ROYER – Team APO – IRIT Amphi C002
    Friday 11 December 2015, 14h30
    Task-based multifrontal QR solver for heterogeneous architectures
    Florent LOPEZ – Team APO – IRIT INP-ENSEEIHT, Salle des thèses
    Tuesday 27 January 2015, 14h00
    Hybridation d’algorithmes évolutionnaires et de méthodes d’intervalles pour l’optimisation de problèmes difficiles
    Charlie VANARET – Team APO – IRIT UT3 Paul Sabatier, IRIT, Auditorium J. Herbrand
    Wednesday 13 January 2016 – Friday 15 January 2016
    Workshop du LabEx CIMI Optimization and Data Assimilation
    CERFACS, Toulouse
    #congres Know more
    Monday 11 January 2016 – Tuesday 12 January 2016
    Workshop du LabEx CIMI Parallel In Time Methods
    IMT – Bât. 1R3
    #congres Know more
    Wednesday 28 October 2015 – Friday 30 October 2015
    KEy topics in orbit Propagation Applied to Space Situational Awareness
    INP-ENSEEIHT, Auditorium
    #congres Know more
    Monday 11 March 2019, 15h00 – 16h00
    SPOT Seminar : High-order multilevel optimization strategies and their application to the training of ANNs
    Elisa RICCETTI – Post-doctorante IRIT – Equipe APO INP-ENSEEIHT, Salle des thèses
    Monday 11 March 2019, 14h00 – 15h00
    SPOT Seminar : Recent results in worst-case evaluation complexity for smooth and non-smooth, exact and inexact, nonconvex optimization
    Philippe TOINT – Université de Namur (Belgique) INP-ENSEEIHT, Salle des thèses
    Tuesday 8 January 2019, 14h00 – 15h30
    Nonconvex optimization with complexity guarantees: a Newton-CG approach
    Clément ROYER – Team APO – ENSEEIHT INP-ENSEEIHT, Salle des thèses
    Tuesday 20 February 2018, 12h15 – 13h00
    Dynamics-based reduction of data assimilation for chaotic models and the role of covariance inflation in reduced-rank filters
    Alberto CARRASSI – Nansen Environmental and Remote Sensing Center, Bergen (Norvège) INP-ENSEEIHT, Salle des thèses
    Monday 22 May 2017, 15h00 – 16h00
    Meeting SPOT : Classification algébrique pour le contrôle optimal en Imagerie à Résonance Magnétique
    Thibaut VERRON – Team APO – IRIT (France) INP-ENSEEIHT, Salle des thèses
    Monday 22 May 2017, 14h00 – 15h00
    Meeting SPOT : Data Analytic UQ cascade for aircraft shape design
    Bijan MOHAMMADI – Université de Montpellier INP-ENSEEIHT, Salle des thèses
    Wednesday 26 April 2017, 10h30 – 12h00
    Aventures dans la jungle des ordres élévés en optimisation
    Philippe TOINT – FUNDP Namur, Chaire d’Excellence CIMI (Belgique) IMT, Salle de conférence MIP (1er étage, bât. 1R3)
    Wednesday 26 September 2018, 15h00
    Scalability of parallel sparse direct solvers: methods, memory and performance
    Alfredo BUTTARI – Team APO – IRIT INP-ENSEEIHT, Salle des thèses
    Thursday 1 June 2017 – Friday 2 June 2017
    Journées utilisateurs de MUMPS (MUltifrontal Massively Parallel sparse direct Solver
    INRIA, Montbonnot