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Igor Simunec

postdoctoral researcher
EPFL
igor.simunec (at) epfl.ch


About me

I am currently a postdoctoral researcher in the HPNALGS group at EPFL (Lausanne, Switzerland), led by Prof. Laura Grigori. I have obtained my PhD at Scuola Normale Superiore (Pisa, Italy) in 2024, under the supervision of Prof. Michele Benzi. My PhD thesis is available here.

My research interests are in numerical linear algebra and scientific computing. Specifically, my research focuses on polynomial and rational Krylov subspace methods for computing matrix functions, and on randomized algorithms for linear algebra problems. I am also interested in trace estimation and in problems arising in network science, such as the computation of centrality measures and dynamics on graphs, that can be formulated in terms of matrix functions. You can find my CV here.

Publications

    Preprints

  1. Laura Grigori, Daniel Kressner, Nian Shao, Igor Simunec, Restoring similarity in randomized Krylov methods with applications to eigenvalue problems and matrix functions, arXiv:2601.10248, 2026.
  2. Jean-Guillaume de Damas, Laura Grigori, Igor Simunec, Edouard Timsit, Randomized orthogonalization and Krylov subspace methods principles and algorithms, arXiv:2512.15455, 2025.
  3. Laura Grigori, Lorenzo Piccinini, Igor Simunec, Randomized biorthogonalization through a two-sided Gram-Schmidt process, arXiv:2509.04386, 2025.
  4. Michele Benzi, Michele Rinelli, Igor Simunec, Estimation of spectral gaps for sparse symmetric matrices, arXiv:2410.15349, 2024 (to appear in Numerische Mathematik).

    5. Journal Articles

  5. Angelo A. Casulli, Igor Simunec, A low-memory Lanczos method with rational Krylov compression for matrix functions, SIAM Journal on Scientific Computing 47(3), 2025.
  6. Igor Simunec, Error bounds for the approximation of matrix functions with rational Krylov methods, Numerical Linear Algebra with Applications 31(5), 2024.
  7. Stefan Güttel, Igor Simunec, A sketch-and-select Arnoldi process, SIAM Journal on Scientific Computing 46(4), 2024.
  8. Michele Benzi, Michele Rinelli, Igor Simunec, Computation of the von Neumann entropy of large matrices via trace estimators and rational Krylov methods, Numerische Mathematik 155, 2023.
  9. Angelo A. Casulli, Igor Simunec, Computation of generalized matrix functions with rational Krylov methods, Mathematics of Computation 92, 2023.
  10. Michele Benzi, Igor Simunec, Rational Krylov methods for fractional diffusion problems on graphs, BIT Numerical Mathematics 62, 2022.
  11. Michele Benzi, Daniele Bertaccini, Fabio Durastante, Igor Simunec, Non-local network dynamics via fractional graph Laplacians, Journal of Complex Networks 8(3), 2020.

    12. PhD Thesis

  12. Igor Simunec, Advances in polynomial and rational Krylov methods for matrix functions with applications, PhD Thesis, Scuola Normale Superiore, 2024.