Résumé
OpenTelemac suffers from numerical reproducibil-ity failures. In parallel simulations, the domain distribution toward units computing with floating-point arithmetic may yield different numerical results. Numerical reproducibility is a requested feature to facilitate the debug, the validation and the test of industrial or large codes. We present how to apply compensation techniques to recover reproducibility in the finite element computation of a hydrodynamics simulation. Compensation is used in both the building and the resolution phases of the linear system which are not reproducible in the current version of the software. Here the building step relies on the element-by-element storage mode and the solving step applies the conjugated gradient algorithm. We also measure that the running time extra-cost of the reproducible version is reasonable enough in practice.