Gabriel Peyré
@
gabrielpeyre
Paris


CNRS researcher at the DMA, École Normale Supérieure. One tweet a day on computational mathematics.

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Tweets 
Gabriel Peyré
@gabrielpeyre

4h  
Oldies but goldies: S. Farsiu, M.D. Robinson, M. Elad, P. Milanfar, Fast and robust multiframe super resolution, 2004. Introduced L1type robust fidelity terms for video superresolution. en.wikipedia.org/wiki/Superres… pic.twitter.com/dXm9zlKoTc


Gabriel Peyré retweeted  
Gabriel Peyré
@gabrielpeyre

Sep 2  
We are starting a new seminar @ENS_ULM "DHAI  When Digital Humanities Meet Artificial Intelligence". First speaker is Alexei Efros (Berkeley), sept. 17th, 2019, 18h20h, "Finding Visual Patterns in Large Image Collections" dhaiseminar.github.io pic.twitter.com/3b0q8owSCh


Gabriel Peyré
@gabrielpeyre

Sep 13  
The Brachistochrone problem was solved by Bernoulli and is the birth of calculus of variations. en.wikipedia.org/wiki/Calculus_… en.wikipedia.org/wiki/Brachisto… pic.twitter.com/g6FY6u6riZ


Gabriel Peyré retweeted  
Ian Goodfellow
@igoodfel

Sep 12  
Hey @goodfellow_ian I keep getting sent your invitations to present at some wonderful conferences  maybe one day I should accept and just rock up and give them the latest in norovirus biology or field sequencing of viruses think they'd notice?


Gabriel Peyré
@gabrielpeyre

Sep 12  
Oldies but Goldies: David Donoho, Iain Johnstone, Ideal spatial adaptation by wavelet shrinkage, 1995. Introduces the soft thresholding to solve denoising by leveraging the sparsity of the data in some dictionary (e.g. wavelets). pic.twitter.com/hTKsHvAt37


Gabriel Peyré
@gabrielpeyre

Sep 11  
Moreau’s decomposition generalizes the orthogonal decomposition from linear spaces to convex functions. It can also be generalized beyond Euclidean spaces using Bregman divergences in place of Euclidean distances.
hal.archivesouvertes.fr/hal01076974/d… pic.twitter.com/EMj4UOV7K5


Gabriel Peyré retweeted  
Eric Arnebäck
@erkaman2

Sep 11  
when shading geometry, normals are interpolated from the vertex normals. this allows even lowres meshes to look smooth. made a short visualization of this: pic.twitter.com/YslKNatHog


Gabriel Peyré
@gabrielpeyre

Sep 10  
Oldies but Goldies: L. Lovasz and B. Szegedy. Limits of dense graph sequences, 2006. Graphons are both continuous limits of dense discrete graphs and models to sample random dense graphs. The natural topology is the cutmetric. en.wikipedia.org/wiki/Graphon pic.twitter.com/E7n6sqk0ty


Gabriel Peyré
@gabrielpeyre

Sep 10  
It is the orthogonal projector on the set of orthogonal matrices btw.


Gabriel Peyré
@gabrielpeyre

Sep 10  
It is not really Moore Penrose, it is rather simply putting the singular values of M to 1. Moore Penrose would invert them. Here from M=U*diag(s)*V the optimal rotation is U*V.


Gabriel Peyré
@gabrielpeyre

Sep 9  
In the static regime, the electric / magnetic fields generated by point sources is the superposition of radial monopoles / dipoles. en.wikipedia.org/wiki/Electroma… pic.twitter.com/GCnqyvZPhH


Gabriel Peyré
@gabrielpeyre

Sep 9  
That was my initial reasoning but I should have used a simpler red/blue colormap. Next time...


Gabriel Peyré
@gabrielpeyre

Sep 8  
Optimal Transport meets Focaccia!


Gabriel Peyré
@gabrielpeyre

Sep 8  
Oldies but goldies: A. Nadas, Least squares and maximum likelihood estimation of rigid motion. KabschNadas formula solves orthogonal least square problem (aka orthogonal procrustes). At the heart of the iterative closest point method for registration. en.wikipedia.org/wiki/Kabsch_al… pic.twitter.com/4nivqkielW


Gabriel Peyré
@gabrielpeyre

Sep 7  
Heat diffusion vs. wave equation on a surface. en.wikipedia.org/wiki/Laplace%E… pic.twitter.com/qSF24M22OM


Gabriel Peyré
@gabrielpeyre

Sep 6  
Oldies but Goldies: Richard Karp, Reducibility Among Combinatorial Problems, 1972.
Proved 21 problems to be NPcomplete, among which the TSP. en.wikipedia.org/wiki/NPhardne… pic.twitter.com/KybwbaeSuW


Gabriel Peyré
@gabrielpeyre

Sep 5  
Matrix decompositions come in many flavors! en.wikipedia.org/wiki/Matrix_de… pic.twitter.com/v9KesYpW6q


Gabriel Peyré
@gabrielpeyre

Sep 5  
This is a great reference!! Thx! Are you aware of applications of this method? [side note: the proof of the main theorem "it has a limit and its derivative goes to zero" seems a bit fast, a function could have a limit without his derivative going to zero, no?]


Gabriel Peyré
@gabrielpeyre

Sep 5  
So true :) I love this algorithm so much! I am desesperatly looking for a descente picture of Richard Dennis Sinkhorn. pic.twitter.com/QTzIZ8BUGo


Gabriel Peyré
@gabrielpeyre

Sep 5  
I hope it is clear by now that convex cones is a strongly recurring theme in my tweets... pic.twitter.com/rGE0Nz8ddY

