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jethkl

558 karma · joined March 12, 2022

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jethkl··on Cubic spline interpolation
I am unaware of any effort in that direction, but I did find a 1987 paper by Höllig [1] that seems to do a kind of converse (approximates FEM solutions using splines. I haven't read the paper, but that's my quick take). Recovering splines using a FEM might be an interesting learning exercise, since the analytic solution is known and the model seems simple. The motivating physical model is described by flat splines [2], and Carl de Boor has photographs of physical splines in action [3].

[1] https://www.semanticscholar.org/paper/Finite-element-methods...

[2] https://en.wikipedia.org/wiki/Flat_spline

[3] https://pages.cs.wisc.edu/~deboor/draftspline.html

jethkl··on Cubic spline interpolation
Spline interpolation is a rich and extensively studied field, dating back to at least the 1940s. Here are a few comments about related work. The interpolation algorithm itself can be adjusted in numerous ways. One effective algorithm for reducing overshooting artifacts is Akima spline interpolation, but there are many others. Cubic splines have noteworthy theoretical properties; you can search for "energy minimizer cubic spline" to find out more. As already mentioned in @creata's comment, instead of using Gaussian elimination, you can take advantage of the fact that the matrix is banded and solve it using a banded solve algorithm (search for DGBSV in LAPACK). There is also research that explores the relationship between shift-invariant spaces and functions that can be expressed as a linear combination of splines. Finally, multivariate interpolation is an extension of the 1-d theory to n-d. This is used in image and surface interpolation, for example.
jethkl··on This code smells of desperation
Add to the mix bug reports like, "This worked on the Gateway when the Epson was freshly plugged into the LPR port but crashed after the Epson had printed 5 pages. If we remove our sound card, then no more problems..." Microsoft's strategy was to support legacy and buggy hardware -- this reduced friction for OEMs and helped expand the market, but it also caused a lot of trouble.
jethkl··on Demand and ETR Forecasting at Airports
The post lacks performance metrics, so it is impossible to know if their effort was worth it. It would be improved by explaining how performance is assessed and why their method is better than an existing or much simpler (e.g., rules-based) baseline.
jethkl··on Physicists discover that gravity can create light
Related: https://en.wikipedia.org/wiki/Kugelblitz_(astrophysics)

See also: https://www.youtube.com/watch?v=v3hd3AI2CAA

jethkl··on The electron is so round that it’s ruling out potential new particles
The Standard Model predicts a vanishingly tiny EDM for the electron — nearly a million times smaller than what current techniques can probe.

This is a big achievement, but a lot more work in this direction remains.

jethkl··on Jaccard Index
Interesting - I also used Jaccard similarity to classify clusters of malicious ad traffic schemes. The idea worked well. It was unclear if the similarity was due to mimicry or authorship, but that did not matter for our use.
jethkl··on Towards quantum computers that are robust to errors
"Towards" in a title usually means the authors didn't do what follows in the title. I have no opinion on the article (and no expertise in the field), but whenever I see "towards", my aim in reading the article often shifts to understand where the authors got stuck.
jethkl··on Ask HN: Something you’ve done your whole life that you realized is wrong?
I thought colorblindness tests were designed to be tricky and subtle, so I always passed them through very close inspection. I'm just colorblind.
jethkl··on What Is Our Universe Expanding Into?
Not at all! I had the same question. Sorry for any misunderstanding, I edited my comment.
jethkl··on What Is Our Universe Expanding Into?
An equivalent reformulation: is there a point where most of everything is behind you? [edited]
jethkl··on Ask HN: Concepts that clicked only years after you first encountered them?
The axiom of choice, Tychonoff's theorem, and the open mapping theorem [0, 1, 2]. Each one took me, in my view, much too long to grasp.

[0] https://en.wikipedia.org/wiki/Axiom_of_choice

[1] https://en.wikipedia.org/wiki/Tychonoff%27s_theorem

[2] https://en.wikipedia.org/wiki/Open_mapping_theorem_(function...

jethkl··on Thousands trapped on Pine Ridge burn clothes for warmth in wake of storm
Firewood deliveries have been a regular occurrence in past years [0,1]. It seems plausible that these past deliveries established a central place where wood is stored, and it also established a local norm where firewood is distributed. Also, this is the high plains where trees grow near rivers but basically don't grow in outlying areas, with the result that general access to wood is not easy for everyone. So it's also plausible that local conditions have established another local norm where maintaining a 3 month stash of firewood is just not done.

[0] https://www.forestsandrangelands.gov/documents/success/rushm...

[1] https://www.blackhillsfox.com/content/news/Military-supplies...

jethkl··on Thousands trapped on Pine Ridge burn clothes for warmth in wake of storm
From TFA: “Our wood pile remains inaccessible.” They have wood but they cannot reach it to make deliveries to people in the area. Several decades ago, I recall driving along I90 in SD a few days after a large storm, and we saw drifts as tall as the highway underpasses. It was incredible. Driven snow takes on a texture that is different from powder, more like soft concrete. When the snow is sufficiently deep, there is no place to put it even if you are able to shovel or plow it.
jethkl··on How to sell tickets fairly
Weird that this got downvoted. In response to "Is ${artist} that good?", I link to an objective list of awards and accolades showing that ${artist} is very good at their job. Compare Swift's success against the Beatles, Dolly Parton [1,2] or anybody else, and it's a very strong showing. If you don't like the art, that's a completely different matter. But in the sense of whether Swift is good in the way that matters here, the answer is clearly, "Yes."

[1] https://en.wikipedia.org/wiki/List_of_awards_and_nominations...

[2] https://en.wikipedia.org/wiki/List_of_awards_and_nominations...

jethkl··on How to sell tickets fairly
Yes. "As of 2022, Swift has broken 84 Guinness World Records, of which 13 times she broke her own record or regained it, and 74 remain unbroken." [1]

[1] https://en.wikipedia.org/wiki/List_of_awards_and_nominations...

jethkl··on Moon Disaster
This project is from 2019. The tools to do this are now more widely available and the realism has advanced considerably since then. This project was an early example that illustrated to a wide audience that audio and video are no longer reliable sources of truth. By comparison, the techniques used in Forrest Gump (1994) look crude.
jethkl··on Nadia Boulanger
Testimonials of her knowledge and talent are awe-inspiring. I've known or met in passing several composers and musicians who studied with her. She taught so many of that era. If interested in this sort of thing, there is a list of some of her students [1].

[1] https://en.wikipedia.org/wiki/List_of_music_students_by_teac...

jethkl··on Show HN: Open source data discovery and observability platform
I see the motivation and skill of your group, and I hope you can retain that and build a useful contribution. I also see the extraordinary effort required to get to this point, and many projects fail to get this far, so congratulations. Something is obviously going well.

However, I am unmoved by your list of key wins (details below). If you indeed built something useful, is there a different way to deliver your message about the functionality that you enable?

Here are my reactions:

1) Shorten data discovery phase. In my experience, analysts and data scientists are always very familiar with what relevant data exists, or else they can find the right people to acquire what data they need. Often, kick-off meetings for new projects cover with stakeholders which data is useful.

2) Have transparency on how and by whom the data is used. For publicly available data, this is not something that a company usually cares about. Internal and proprietary data management is already a very mature space, and every company with such data already has processes in place to manage data access. I grant this is often a mess, but I also don't see any global solution on the horizon.

3) Foster data culture by continuous compliance and data quality monitoring. Data quality monitoring is extremely complex. I have seen many claims over many years of tools that solve this problem broadly, but I have yet to see any solution that matches the claims.

4) Accelerate data insights. This is a very bold claim for a new project, especially given the many (5+) decades of work and experience developing tools and techniques for data insights.

5) Know the sources of your dashboards and ad hoc reports. All dashboards I am aware of surface this sort of information.

6) Deprecate outdated objects responsibly by assessing and mitigating the risks. This is a good idea, but it is challenging in practice, as illustrated by several prominent examples [1,2,3].

Finally, unrelated to the above, your project's name (ODD) is very similar to the name used by the Outlier Detection DataSets (ODDS) project [4]

Good luck.

[1] http://www.lenna.org/editor.html

[2] https://scikit-learn.org/stable/modules/generated/sklearn.da...

[3] https://deepai.org/dataset/fb15k and https://paperswithcode.com/dataset/fb15k-237

[4] http://odds.cs.stonybrook.edu

jethkl··on Gcloud storage: Faster data transfers for Cloud Storage
This triggered a memory from my distant (12+ years ago) past: Globus Grid FTP had this capability, and it was awesome for bulk data transfer [1].

[1] https://docs.globus.org/globus-connect-server/v4/man/globus-...

jethkl··on Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]
Linking to the cited followup study that ran 36 years later. Similar results are reported. https://files.eric.ed.gov/fulltext/ED565462.pdf
jethkl··on Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]
Perhaps. However, if there were any evidence of 1-or-2 versus 19-or-21 type thinking, I would expect the results to be non-random. But the results of asking students who should know the answer were equivalent to random guesses.
jethkl··on Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]
Yes. I interpret the results as evidence of serious and systemic problems.
jethkl··on Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]
I agree that this is a trivial question. But the linked pdf explains why it is an interesting question: it was posed to 20k US 8th graders in 1978, and the results were random. The same question was posed to 48 US students in 2014, and results were again random.
jethkl··on Is 1, 2, 19 or 21 closest to 12/13 + 7/9? [pdf]
In 1978, a US-based study posed this question to 20,000 8th graders. Just 24% selected the correct answer. This is basically equivalent a random guess. In 2014, the same question was posed to 48 suburban US students. Only 27% selected the correct answer.
jethkl··on Dvořák In Iowa (2020)
Well, he is! His cello concerto is standard repertoire across the world, and his New World Symphony is standard in the US. He should also be known for originating the ET theme [1,2], but that's not how things work.

[1] https://www.youtube.com/watch?v=vDPkMvUAgqo&t=1955s

[2] https://www.youtube.com/watch?v=2-qrMz-JAzo&list=RD2-qrMz-JA...

jethkl··on Matplotlib 3.6
The "I'll fix it later" aesthetic of matplotlib is addressed well by seaborn [1], which is built on top of matplotlib. Seaborn also works gracefully with Pandas. The killer feature for me of seaborn is "sns.despine()".

PyX is new to me, but it looks like it hasn't been updated in a while [2, 3].

[1] https://seaborn.pydata.org

[2] https://pyx-project.org/news.html

[3] https://github.com/pyx-project/pyx

jethkl··on Mathematics Genealogy Project
It is a curious collection:

- Leonardo da Vinci https://www.genealogy.math.ndsu.nodak.edu/id.php?id=131700

- Theodore John Kaczynski https://www.genealogy.math.ndsu.nodak.edu/id.php?id=5470

- Ahmad A. H. Chalabi https://www.genealogy.math.ndsu.nodak.edu/id.php?id=6597

- Brian Harold May https://www.genealogy.math.ndsu.nodak.edu/id.php?id=217395

- Angela Dorothea Merkel https://www.genealogy.math.ndsu.nodak.edu/id.php?id=223396

- Frank Ryan https://www.genealogy.math.ndsu.nodak.edu/id.php?id=43254

- Christopher Wren https://www.genealogy.math.ndsu.nodak.edu/id.php?id=234537

- James Harris Simons https://www.genealogy.math.ndsu.nodak.edu/id.php?id=32049

- Robert Leroy Mercer https://www.genealogy.math.ndsu.nodak.edu/id.php?id=221133

- Stephen Wolfram https://www.genealogy.math.ndsu.nodak.edu/id.php?id=114676

- Steven Chu https://www.genealogy.math.ndsu.nodak.edu/id.php?id=239349

jethkl··on Show HN: EthicalAds – Privacy-first ad network for developers
All parties in the ecosystem tolerate some levels of fraud. The threshold for action varies over time (e.g., if ${bot-detector-company} has a press release that blames the Russians, people will care for a few weeks) and it depends on who is complaining. Detection of low-hanging fruit at small scales is often straightforward, and you can detect the clumsiest fraudsters using basic analytics tools. But detection at scale is hard, especially if you have a large number of clients that are not a homogeneous or predictable. The nature of organic traffic visiting streaming platforms, ticket sales sites, news sites, blogs, etc. are all very different. From my experience, the hardest part of the fraud detection space is getting some action in response to a fraud alert.

(Disclosure: I used to work in ad fraud detection)

jethkl··on Efficient simulation through linear algebra
+1 to the article. Good job.

One suggestion: when experimenting, monitor numerical precision. This is important if matrices are poorly conditioned or if the inverse is updated over many iterations.

Also possibly of interest are Suitesparse and a Python-based guide that uses it [1,2].

[1] https://people.engr.tamu.edu/davis/suitesparse.html

[2] https://cvxopt.org/userguide/spsolvers.html#

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