Stefan Güttel

collaborators

8 papers

math.NA2026

Uniform-in-time rational approximation of the matrix exponential with real poles

Stefan GÃ¼ttel, Shuai Shao

We propose two new approaches for constructing families of rational functions with shared real poles that nearly uniformly approximate the functions $exp (- t z)$ for $z \geq 0$ and $…

math.NA2026

Concentrated real-pole uniform-in-time approximation of the matrix exponential

Stefan GÃ¼ttel, Shuai Shao

We propose an asympotically optimal choice of shared concentrated real poles of a family of rational approximants of time-dependent exponential functions $exp (- t z)$ for $z \geq 0$ …

math.NA2026

Scalable parallel 3-D TEM inversion via rational approximation of the matrix exponential

Ralph-Uwe BÃ¶rner, Stefan GÃ¼ttel, Thomas GÃ¼nther

We present a novel parallel implementation for large-scale three-dimensional electromagnetic inversion based on a Gauss-Newton framework combined with a rational near-best approxim…

math.NA2026

Stabilizing randomized GMRES through flexible GMRES

Stefan GÃ¼ttel, John W. Pearson

We explore the use of flexible GMRES as an outer wrapper for sketched GMRES. Building on a new bound for the residual of FGMRES in terms of the residual of the preconditioner, we d…

math.NA2026

Flexible GMRES converges in two phases

Stefan GÃ¼ttel, Lauri Nyman

We derive a sharp upper bound on the residuals produced by the flexible GMRES (FGMRES) method. The bound shows that FGMRES exhibits two phases of convergence depending on the resid…

math.NA2026

Data-driven discovery of chemical reaction networks

Abraham Reyes-Velazquez, Stefan GÃ¼ttel, Igor Larrosa +1

We propose a unified framework that allows for the full mechanistic reconstruction of chemical reaction networks (CRNs) from concentration data. The framework utilizes an integral…