Léopold Cambier,
Ph.D. Student, ICME, Stanford University
Advisor: Eric Darve
Office in ICME: Huang Engineering Center, Suite 060 (Bottom level)
Office in Mechanical Engineering: Building 520, Room 133


Current Work

My current interests are the design of new, robust and fast sparse linear solver.

More precisely, we are trying to combine ideas for (sparse) direct solvers and fast algorithms. On one side, direct solvers use fill-reducing orderings (i.e., the Nested Dissection in most cases) to reduce fill-in during the factorization, and to exhibit parallelism in the operations. On the other side, fast algorithms use the fact that for a large class of linear systems, far-field interactions are typically low-rank. By introducing this idea, we are able to eliminate many more unknowns than usual, at a fraction of the cost. The result is an algorithm with a complexity much closer to O(n), able to solve large systems at a fraction of the cost of direct methods, while keeping most of they good properties.


I did my Bachelor & Master (2010-2015) in Engineering at Université catholique de Louvain (Belgium). During that time, I spent 3 months at MIT working with Prof. Laurent Demanet on seismic imaging and full wave inversion. I did my master thesis with Prof. P.-A. Absil, working on Low-Rank Matrix Compression. In 2015, after my Master at UCLouvain, I moved to Stanford to start my Ph.D. I started working with Prof. Eric Darve (Mechanical Engineering) on numerical linear algebra. After some work on low-rank kernel matrix approximation, I am now working on large sparse linear systems. We are trying to bridge the gap between direct methods (accurate, reliable but expensive) and preconditioners (cheap but complex to work with or very domain specific). We develop highly efficient incomplete factorization methods for large sparse linear systems, typically arising from PDE’s applications. During my PhD, I also did two interships (summers 2016 and 2017) at NVidia, working on cuDNN and cuBLAS.