Stefan Güttel

609 posts

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Stefan Güttel

Stefan Güttel

@guettel

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

Manchester, UK Sumali Ağustos 2013
0 Sinusundan713 Mga Tagasunod
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INEGO
INEGO@inegomusic·
We are playing the awesome @AfterAllFest this weekend!!!! Friends old and new come and join the party @thepeerhat on Sat night (on stage at 9). Buzzin to share a stage with so many awesome acts. Get your tickets here 👇 fatsoma.com/e/848wbm7y/la/… See you down the front 🌠🎶🐝💫
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Reid Atcheson
Reid Atcheson@reidatcheson·
any guess on what I'm about to try and do
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Stefan Güttel
Stefan Güttel@guettel·
@reidatcheson One can sometimes do a little better by selecting the k vectors to orthogonalize against from *all* previous basis vectors, not just the latest ones arxiv.org/abs/2306.03592 But the cond number will grow exponentially eventually for nonsymmetric A (see the thm).
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Reid Atcheson
Reid Atcheson@reidatcheson·
It's a known fact that there aren't stable 3-term recurrences for orthogonalizing Krylov vectors for symmetric matrices, even though in exact precision the Lanczos recurrence does the job. But what if you orthogonalize against a fixed window of past vectors (more than 3?)
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Stefan Güttel
Stefan Güttel@guettel·
@MarcelSchweitz1 Nice work! We just posted arxiv.org/abs/2311.14206 -- now I wonder how your algorithm would compare to using sketched GMRES for solving the linear system formulation of the matrix equation (with a Kronecker structured sketch operator)
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Marcel Schweitzer
Marcel Schweitzer@MarcelSchweitz1·
New preprint on randomized Krylov methods for large-scale Sylvester/Lyapunov equations (algorithmic aspects + theoretical analysis). Turns out to be highly competitive with state-of-the-art rational Krylov both regarding run time and memory consumption: arxiv.org/abs/2311.16019
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Kirk Soodhalter
Kirk Soodhalter@KirkMSoodhalter·
New work on combining sketching and Krylov subspace recycling with Liam Burke from @MathsTCD and Stefan Güttel @guettel. New algorithm GMRES_SDR and theoretical analysis of sketched GMRES, which we build upon to analyse our new method. arxiv.org/abs/2311.14206
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Stefan Güttel
Stefan Güttel@guettel·
CLASSIX a new clustering method that provides textual and visual explanations of its outputs. It is also super fast. It clusters 2 million data points in under a second on a laptop where DBSCAN would require an hour. #scaling-test-classix-vs-dbscan" target="_blank" rel="nofollow noopener">github.com/nla-group/clas…
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Stefan Güttel
Stefan Güttel@guettel·
@latzplacian I read "Counterexamples in Analysis" while studying Wegert's 4-semester Analysis course at Freiberg. These counterexamples really annoyed me and I much prefer Complex Analysis now 😅
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Oded Rechavi
Oded Rechavi@OdedRechavi·
Name a job that allows you to travel and see the world more than being in academia
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Math World
Math World@Math_World_·
Which number is missing? In how many seconds did you find?
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Stefan Güttel
Stefan Güttel@guettel·
Our apartment in Varna, Bulgaria, is right above the @twitter headquarters
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