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kkylin

1,411 karma · joined August 4, 2011

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kkylin··on What California is learning from solar panels built over irrigation canals
Happened right here too: thieves opened up man hole covers in city parks and took the wires. The city now has large boulders right over those man hole covers...
kkylin··on Jean-Pierre Serre turns 100
Euler was a master manipulator of formal expressions; don't think it bothered him very much whether, e.g., an infinite series converged or not. (Unfortunately don't remember a source for this offhand -- maybe a leftover impression from having read ET Bell's book long ago? I also don't know how reliable Bell is.)

Edit: added semi-source

kkylin··on Necker, 1832: "An optical phænomenon on viewing a figure of a geometrical solid"
Just from the title it sounds really cool, but I guess the server got the hug of death (kept getting timeout)
kkylin··on How an MIT research project became the Julia programming language
There's understandably been a focus on speed, but what I really like about Julia is being able to write clear code: it has a lot of the flexibility and expressiveness that I like in Lisps, but with better numerical libraries than most Lisps/Schemes, and I really like prototyping algorithms in it. To me (an applied mathematician) it is just a nice tool for thinking in. Not having to compromise too much on speed is a big bonus.
kkylin··on Europe's summer drought is so extreme that desertification is a growing threat
I just came back to CA from the UK, and the two places looked surprisingly alike: yellow fields everywhere
kkylin··on What's new in Emacs 31.1
Unfortunately the NS/macOS version still needs work as far as I can tell. Even not fully featured it's still useful: I prefer reading PDF in xwidget-webkit than pdf-tools, and it's great to have Jupyter notebooks running inside a browser inside Emacs.
kkylin··on The lost civic life of movie rental stores
Where I live we still have a locally owned video rental store, though several years ago they put in a bar and now it's more a bar with a video section than a video store where you can get beer and watch movies. We do still rent when there's something we can't stream on one of the services we pay for; I much rather do that than give more $ to Amazon and the like.
kkylin··on Claude Fable produced a counterexample to the Jacobian Conjecture
Related & of interest: https://xenaproject.wordpress.com/2026/07/20/human-mathemati...
kkylin··on The Boeing 747 begins its final descent
Actually we weren't (& aren't) able to afford this kind of thing. Dad worked for the airline & somehow got this perk, just once.
kkylin··on The Boeing 747 begins its final descent
We got front lower deck seats once when I was a kid. My sister and I had extra open floor space for playing. It was great.
kkylin··on The Life and Works of Raoul Bott (2002)
Bott is often quoted as saying "Evrey mathematician has a secret weapon. Mine is Morse theory." Every time I see his name I've tried to look up a source. Finally found one:

https://mathoverflow.net/questions/100316/raoul-botts-quote-...

Anyway if you enjoyed this you might also enjoy

https://www.numdam.org/item/10.1007/BF02698544.pdf

kkylin··on Lost Images from the 1945 Trinity Nuclear Test Restored
Slightly off topic (since there's already been so many better answers than I can write), but our knowledge of the dino-slaying asteroid came much later: https://en.wikipedia.org/wiki/Alvarez_hypothesis
kkylin··on What Do Gödel's Incompleteness Theorems Mean?
I really do think the incompleteness theorems deserve the attention they get, not just because of what they say about efforts to formalize mathematics and because of the historical context -- remember Gödel numbers came (just) before Turing and the first recognizably modern electronic computers. That numbers can represent things that are not numbers was (IMO) a revolutionary idea.

Having said all that, I'd taken mathematical logic in college to learn about incompletenss, but the most interesting things I got out of it were completeness and compactness. Non-standard models really can be quite interesting.

kkylin··on The Aperiodic Table
In addition to the above links on quasicrystals etc, it may help to have a bit of context on periodic tilings, which have very precise mathematical properties: https://en.wikipedia.org/wiki/Lattice_(group).

The structure of the periodic table itself can also be understood, to leading order anyway, in symmetry terms. See for example https://mathstodon.xyz/@johncarlosbaez/112540366778806757 and references there.

kkylin··on Some Unusual Trees
Of course one reads a (nice) post like this and must add one's favorite not on the list. Here's mine: https://en.wikipedia.org/wiki/Fouquieria_columnaris
kkylin··on New iPad Air, powered by M4
I had an even older iPad I was happily using for similar use cases. Until one day a family member bricked it and I needed to factory reset. No big deal, I thought -- nothing important on it. Turns out it needed to phone home to do the factory reset, and since the server it wanted to talk to was no longer up (or perhaps the address changed?) I couldn't factory reset the iPad.

If someone has a work-around I'd love to hear it. Until then, or until Apple changes this design, I think I'm done with iPads. I don't want to pay that much to "own" something that Apple can simply make obsolete by reconfiguring or turning off a server somewhere.

Edit: fix typo

kkylin··on GNU Texmacs
In my couple decades as an academic mathematician I've only ever met one. He was a strong advocate, and got me to install & try it, but I could never convert to using it fulltime.
kkylin··on In Praise of APL (1977)
I've had the same dream! thanks for the pointer.
kkylin··on MIT Missing Semester 2026
Yes, 1.00 was popular with Course 6ers who wanted easy units.
kkylin··on Italian bears living near villages have evolved to be smaller and less agressive
Not just bears it seems: https://www.scientificamerican.com/article/raccoons-are-show...
kkylin··on NOAA deploys new generation of AI-driven global weather models
Came here to say this -- looks like the data assimilation is still done the "old fashioned" way. I wonder how long that will last?
kkylin··on MIT Missing Semester 2026
Yup. Back in my day there was 1.00, a Civil Engineering course, a pretty standard intro to programming in plain old C. I don't know if it still exists. There was nothing of that sort in EECS, though there are lots of IAP courses (which take place in January, before spring semester starts). IMO a month is about right to spend on (leisurely) picking up a programming language for fun. A friend and I learned APL that way.
kkylin··on Size of Life
We've still got this:

https://en.wikipedia.org/wiki/Eunice_aphroditois

Thankfully they don't live on land.

kkylin··on Putting email in its place with Emacs and Mu4e
I have been using mu4e for years, and am generally happy with it, and yet... I've never recommended it to anyone else. Unlike, say, org-mode or magit, which I'd happily evangelize.

The pain points are what other commenters have said:

- I don't find the default config a good fit for me, and run it heavily customized. As someone said everything in Emacs turns into a project...

- Performance can be an issue, especially indexing new mail (and especially if you like to lug around a copy of most of your emails locally as I do). On a laptop while traveling this used to be more of a problem, but newer versions are notieably quicker and newer laptops have better battery life.

- HTML rendering isn't great. Thankfully I don't get too many important messages that isn't just plain text. This might be a reasonable use case for xwidget-webkit though I'd imagine there are security/privacy issues to work out. (Another Emacs project -- yay!)

When I started I thought it would be an efficient way to get through lots of emails, and it has been for the most part. I'm just not sure I've saved time overall unless one counts the hours configuring it as "entertainment / hobby" rather than "work".

kkylin··on Transformers know more than they can tell: Learning the Collatz sequence
:-)

I don't question this decision is sometimes (often) driven by the need to increase publication count. (Which, in turn, happens because people find it esaier to count papers than read them.) But there is a counterpoint here, which is that if you write say a 50-pager (not super common but also not unusual in my area, applied math) and spread several interesting results throughout, odds are good many things in the middle will never see the light of day. Of course one can organize the paper in a way to try to mitigate the effects of this, but sometimes it is better and cleaner to break a long paper into shorter pieces that people can actually digest.

kkylin··on Feynman vs. Computer
That's exactly right. A couple more things:

- Differenting a function composed of simpler pieces always "converges" (the process terminates). One just applies the chain rule. Among other things, this is why automatic differentiation is a thing.

- If you have an analytic function (a function expressible locally as a power series), a surprisingly useful trick is to turn differentiation into integration via the Cauchy integral formula. Provided a good contour can be found, this gives a nice way to evaluate derivatives numerically.

kkylin··on Apple Releases Open Weights Video Model
Thank you so much for all this detail. This is very interesting & quite helpful, and it's great you were able to communicate all this with your friend.

For anyone else interested: I wanted to be able to typeset mathematics (actual formulas) for the students that's as automated as possible. There are 1 or 2 commercial products that can typeset math in Braille (I can't remember the names but can look them up) but not priced for individual use. My university had a license to one of them but only for their own use (duh) and they did not have the staff to dedicate to my students (double duh).

My eventual solution was to compile latex to html, which the students could use with a screen reader. But screen readers were not fully reliable, and very, very slow to use (compared to Braille), making homework and exams take much longer than they need to. I also couldn't include figures this way. I looked around but did not find an easy open source solution for converting documents to Braille. It would be fantastic to be able to do this, formulas and figures included, but I would've been very happy with just the formulas. (This was single variable calculus; I shudder to think what teaching vector calc would have been like.)

FYI Our external vendor was able to convert figures to printed Braille, but I imagine that's a labor intensive process.

Partway through the term we found funding for dedicated "learning assistants" (an undergraduate student who came to class and helped explain what's going on, and also met with the students outside of class). This, as much or more than any tech, was probably the single most imapctful thing.

kkylin··on Apple Releases Open Weights Video Model
Thanks! Did you communicate in "raw" TeX, or was it compiled / encoded for braille? Can you point me at the software you used?
kkylin··on Apple Releases Open Weights Video Model
Like many others, I too would very much like to hear about this.

I taught our entry-level calculus course a few years ago and had two blind students in the class. The technology available for supporting them was abysmal then -- the toolchain for typesetting math for screen readers was unreliable (and anyway very slow), for braille was non-existent, and translating figures into braille involved sending material out to a vendor and waiting weeks. I would love to hear how we may better support our students in subjects like math, chemistry, physics, etc, that depend so much on visualization.

kkylin··on Hard drives on backorder for two years as AI data centers trigger HDD shortage
Question for all of you more knowledgeble than I: can SMART data be tampered with? When I get, say, a refurbished Mac from Apple, I'm trusting Apple won't stoop to that. But a SSD vendor I've never heard of?
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