Stefan Güttel (@guettel) header
Stefan Güttel (@guettel) profile picture

Stefan Güttel

@guettel

Professor of Mathematics @OfficialUoM & @RoyalSociety Industry Fellow. I decompose matrices for a living.

 Manchester, UK
guettel.com
Joined August 2013
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I gave an informal talk on the CLASSIX clustering algorithm in our @nla_grp seminar yesterday. It contains some MATLAB and Python live demos. youtube.com/watch?v=Q-CQBEYX…
Fast and explainable clustering with CLASSIX

Fast and explainable clustering with CLASSIX

This is a talk on the CLASSIX clustering method given on 13 Decembe...

youtube.com
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New work on combining Krylov subspace recycling with randomized sketching for matrix functions and linear systems - arxiv.org/abs/2308.02290 (with Liam Burke @tcddublin)
A plot that shows how Krylov subspace recycling helps to reduce the error when solving a sequence of 20 problems while updating an augmentation space from one problem to the next. The new recycling method is rFOM, and srFOM is its combination with sketching.

ALT A plot that shows how Krylov subspace recycling helps to reduce the error when solving a sequence of 20 problems while updating an augmentation space from one problem to the next. The new recycling method is rFOM, and srFOM is its combination with sketching.

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Our apartment in Varna, Bulgaria, is right above the @twitter headquarters
Image from Stefan Güttel (@guettel)
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A sketch-and-select Arnoldi process. Using randomized sketching to compute a relatively well-conditioned basis of a Krylov space at low cost. Usually much better than truncated Arnoldi. arxiv.org/abs/2306.03592 (with Igor Simunec @scuolanormale)
A MATLAB plot comparing the condition numbers of Krylov bases computed with eight different quasi-orthogonalization processes.

ALT A MATLAB plot comparing the condition numbers of Krylov bases computed with eight different quasi-orthogonalization processes.

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Congratulations to Xinye Chen (@chenxinye2) who successfully defended his PhD thesis on "Fast aggregation-based algorithms for knowledge discovery" today. Many thanks to the examiners @TAH_Sci and @sdrelton and good luck for the next chapter Xinye! #proudsupervisor
Dr Xinye Chen, who just passed his PhD viva, with supervisor in front of the University of Manchester's new Engineering Campus MECD

ALT Dr Xinye Chen, who just passed his PhD viva, with supervisor in front of the University of Manchester's new Engineering Campus MECD

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Great to have @jitseniesen from @mathsleedsuni visiting us @ManUniMaths with a very interesting talk on 'Plasma simulations using Vlasov equations and particle-in-cell methods'
Image from Stefan Güttel (@guettel)
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Excited to join the public lectures at #SIAMCSE23 @TheSIAMNews. What a great way to initiate discussions of the role of Mathematics in solving the world's main challenges.
Image from Stefan Güttel (@guettel)
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Replying to @dphys @PhysicsNews @britishmuseum @BritSciAssoc @BSHSNews @NPLPressOffice
This is the real Stephen Butterworth OBE (1885–1958).
Stephen Butterworth OBE (1885–1958)

ALT Stephen Butterworth OBE (1885–1958)

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NEW PREPRINT @chenxinye2: Sorting-based exact nearest neighbor search (arxiv.org/abs/2212.07679) Native Python implementation often performs significantly faster queries than @scikit_learn's tree methods. Fast indexing and zero hyperparams (as opposed to many approx. NN algs).
Image from Stefan Güttel (@guettel)
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NEW EPRINT: Randomized sketching of nonlinear eigenvalue problems (with @_kreda_ and Bart Vandereycken) We show how to significantly speed up the rational approximation of high-dimensional nonlinear functions while retaining accuracy.
Image from Stefan Güttel (@guettel)
arXiv math.NA Numerical Analysis (@mathNAb) profile picturearXiv math.NA Numerical Analysis@mathNAb23 Nov 2022
Stefan Güttel, Daniel Kressner, Bart Vandereycken: Randomized sketching of nonlinear eigenvalue problems arxiv.org/abs/2211.12175 arxiv.org/pdf/2211.12175
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