Gregory Gundersen
gregorygundersen.com · Personal blog · on HN since 2020
Gregory Gundersen is a machine learning researcher who writes explanatory posts on statistics, linear algebra, probability, and the history of language models.
What HN saysHN commenters praise his explanations of moments, SVD, and matrix inversion, with one calling the SVD post their favorite, and note his use of KaTeX.
28HN people shared it
11linked it in comments
31stories submitted
1.3Kstory points
4 months agolast shared
2020people per year2026
Most-shared posts
- 1Why I Keep a Research Blog3 people · 609 points · first shared 2020 · 72 comments on HN
- 2Understanding Moments3 people · 1 points · first shared 2023 · discussion on HN
- 3Blog3 people · first shared 2020
- 4A History of Large Language Models2 people · 308 points · first shared 2025 · 26 comments on HN
- 5Why Metropolis–Hastings Works2 people · 5 points · first shared 2025 · discussion on HN
- 6The First Ten Years2 people · 3 points · first shared 2025 · 1 comments on HN
- 7Why Shouldn't I Invert That Matrix? (2020)2 people · 3 points · first shared 2022 · discussion on HN
- 8Problem Solving with Dimensional Analysis2 people · 2 points · first shared 2023 · discussion on HN
- 9Understanding Positive Definite Matrices2 people · 2 points · first shared 2024 · discussion on HN
- 10Singular Value Decomposition as Simply as Possible2 people · 1 points · first shared 2020 · discussion on HN
- 11Blog theme2 people · first shared 2020
- 12An Intuitive Explanation of Black–Scholes1 people · 212 points · first shared 2024 · 89 comments on HN
- 13Proof of the Singular Value Decomposition1 people · 110 points · first shared 2024 · 21 comments on HN
- 14Blockchain in 19 Lines of Python (2021)1 people · 15 points · first shared 2023 · 3 comments on HN
- 15How Dangerous Is Biking in New York?1 people · 5 points · first shared 2022 · 1 comments on HN
What HN people wrote when they linked it
ihodes · 2023-04-16
Greg's blog is a great example of Katex in the wild: http://gregorygundersen.com/
mojomark · 2023-10-15
If anyone was frustrated like me on this concept of "moments" I found the following insightful and fascinating:
https://gregorygundersen.com/blog/2020/04/11/moments/
I have no idea how I got through undergrad and graduate school without internalizing this concept that seems so foundational. Whacky
yt-sdb · 2020-06-21
Not an application, but this my favorite explanation of SVD:
http://gregorygundersen.com/blog/2018/12/10/svd/
It's such an important operation that I'd say understanding it changes how you understand a lot of linear algebra. That Kun post is also good.
benrbray · 2020-07-11
This article is a bit rough around the edges, and they really should make it clear when they mean "pseudorandom" vs "random", especially when one goal of the article is ostensibly to explain pseudorandomness to laymen!
As an aside, using a source of random numbers to generate other random objects is quite an interesting problem! For converting from one probability distribution to another, we have classical methods like rejection/importance sampling, and modern deep learning makes constant use of the "reparameterization trick" [1,2]. Looking beyond just numbers, here's a neat trick for generating a random orthogonal matrix:
A = np.random(n,n)
Q,_ = np.qr(A)
With a small correction [3], we can guarantee that our samples have uniform distribution (Haar measure) on the space of all orthogonal matrices:
def haar_measure(n):
# naive method
Z = randn(n,n) + 1j*randn(n,n) / np.sqrt(2);
Q,R = np.linalg.qr(Z);
# correction
d = np.diag(R);
PH = np.diag(d) / np.absolute(d);
return Q @ PH;
For more, read about random matrix theory! As an exercise for the reader, how would you generate: a random symmetric matrix? a random skew-symmetric matrix? a random positive-definite matrix? a random hamiltonian path in a fixed graph?
[1]: http://gregorygundersen.com/blog/2018/04/29/reparameterization/
[2]: https://timvieira.github.io/blog/post/2014/07/31/gumbel-max-trick/
[3]: http://www.ams.org/notices/200705/fea-mezzadri-web.pdf
gwgundersen · 2022-10-12
Re: the first sin, I was told to not invert matrices but never given a satisfying reason. So I wrote a blog post about it:
http://gregorygundersen.com/blog/2020/12/09/matrix-inversion/
ethanweinberger · 2020-07-18
I (shamelessly) stole the layout from Gregory Gundersen's wonderful research blog (https://gregorygundersen.com/blog/). He has instructions on how to replicate it here https://gregorygundersen.com/blog/2020/06/21/blog-theme/
pdm55 · 2020-01-13
For his css files try http://gregorygundersen.com/css/
Better still try his GitHub
https://github.com/gwgundersen especially his notebook software https://github.com/gwgundersen/anno
jimbo1qaz · 2020-01-13
This seems to be a static site generator.
http://gregorygundersen.com/blog/2020/01/12/why-research-blog/ has a HTTP header last updated on 01/13/2020 04:34:31.
http://gregorygundersen.com/blog/2019/12/23/random-fourier-features/ is 01/13/2020 04:34:30, or 1 second earlier.
Also the source code has a link to http://gregorygundersen.com/css/markdown.css which 404's.
archontes · 2021-05-27