Post-Doctoral Research Visit F/M Low-Rank Compression Algorithms for H-matrices

13 Mar 2025
Job Information

Organisation/Company

Inria, the French national research institute for the digital sciences

Research Field

Computer science

Researcher Profile

Recognised Researcher (R2)

Country

France

Application Deadline

31 May 2025 - 00:00 (UTC)

Type of Contract

Temporary

Job Status

Full-time

Hours Per Week

38.5

Offer Starting Date

1 Sep 2025

Is the job funded through the EU Research Framework Programme?

Not funded by a EU programme

Reference Number

2025-08695

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

This project will be carried out within the framework of CONCACE, a joint Inria-Industry team involving Airbus, Cerfacs and Inria, focusing on the theme of composability applied to high-performance computing.
For wave propagation simulations in electromagnetics or acoustics, Airbus makes extensive use of H-matrix solvers to solve surface integral formulations. These techniques use a hierarchical partitioning of the physical object under consideration (e.g. an aircraft) to produce a hierarchical partitioning of the (dense) matrix of the linear system. Most of the matrix blocks thus created are numerically low-rank, and can therefore be stored in compressed form, occupying much less memory space. The H-matrix solver enables us to store these blocks, use them for matrix-vector products and factorize the matrices in our problems while keeping them in this storage format. This is a crucial tool for modeling certain aircraft physics.
The development of the h-matrix library is the fruit of a collaboration since 2010 between Airbus and Inria, it is in C++ and uses the task-based programming paradigm with the StarPU execution engine.  The proposed topic will lead to further development of this h-matrice tool, in collaboration with the industrial partner.

The aim of this 2-year mission - co-funded by Airbus and Inria - is to work on low-rank compression algorithms, which are a fundamental building block of the H-matrix approach. There is a huge variety of algo's fulfilling this role, between classical approaches (SVD, ACA, CUR, ID, ...), randomized variants, reconciliations between these methods and other usual algo's (ACA is for instance a way to rewrite LU), ... Today, H-matrix contains only a few of these algorithms. The aim of the post-doc is :

• enrich the available choice of low-rank compression algo ;
• implement them in a composable way, so that they can be used in the h-matrice library as well as in any other software library;
• to know for each algo its range of effectiveness, in terms of input data (size), target machine (CPU, GPU), precision, execution time, etc.
• be able to dynamically select the most suitable algo at runtime.

As the H-matrices tools at Airbus and Concace are halfway between industry and academic research, the aim of the research within this mission is to identify the most efficient numerical techniques and pass them on to industry for implementation in design offices.

To do this, the various stages of this post-doc will be :

• clarify this diversity of algorithms, identifying the strengths and weaknesses of each, and isolating those that are truly innovative;
• explore and extend the most promising variants (such as geometry-based ACA);
• to implement the most useful methods in the ComposyX software library, the composable linear algebra tool of the Concace project serving to consolidate our work;
• Publication (articles, conferences) of the theoretical and practical results of this work

Where to apply

Website

https://jobs.inria.fr/public/classic/en/offres/2025-08695

Requirements
Skills/Qualifications

•     Linear algebra, algorithms, parallelism
•     C, C++, Python programming
•     Writing articles, oral presentations
•     Ability to alternate collaborative work and autonomy
  Language: French or English

Specific Requirements

For this position, you'll need a good grounding in linear algebra (matrices, vectors, basic algo such as LU, cholesky, SVD, QR, etc.), as well as a good feel for C++ and Python programming. You must be interested in bibliographical research, the analysis of existing algorithms or the design of new ones, the efficient implementation of all this in a pre-existing software framework (which is both complex and demanding), and finally the desire to see your work put to practical use in industry in Airbus design offices.
The position will preferably be based at the Inria center at the University of Bordeaux.

Languages

FRENCH

Level

Basic

Languages

ENGLISH

Level

Good

Additional Information
Benefits

• subsidized meals
• partial reimbursement of public transport costs
• possibility of partial teleworking and flexible organization of working hours
• professional equipment avilable (videoconferencing, loan of computer equipment...)
• access to vocational training
• social security coverage

The gross monthly salary will be 2788€ (before social security contributions and monthly witholding tax)

Selection process

If you are interested by this job, please could you apply on website jobs.inria with the following documents :

• CV
• Cover letter
• recommandation letters

Website for additional job details

https://jobs.inria.fr/public/classic/en/offres/2025-08695

Work Location(s)

Number of offers available

1

Company/Institute

Inria

Country

France

City

Talence

Geofield

Contact

City

LE CHESNAY CEDEX

Website

http://www.inria.fr

Street

Domaine de Voluceau - Rocquencourt

Postal Code

78153

STATUS: EXPIRED

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