HNHacker News
TopNewBestAskShowJobs

sfpotter

1,651 karma · joined August 7, 2022

submissionscomments
sfpotter··on A wave of plastic-free coffee pods and machines
Love my La Pavoni.
sfpotter··on There's never been a better time to go into math (by: 3blue1brown) [video]
I learned to program because I wanted to make video games as a kid. I studied math because I got bored of programming. I worked as a programmer because I needed a job and it was the thing that paid the most among the things I was qualified to do (I actually thought I wanted to be a chef...). I went back to grad school because I thought programming apps was tedious and a dead end and wanted to get a job in research. I got a postdoc because I was pretty decent at it and liked what I was doing. I left academia to go do industrial R&D because academia was a dumpster fire and I needed more money and predictability for my family. I'm now writing niche numerical libraries for a small company because it's what I ended up intensely specializing in and I still like what I'm doing. I'm mixed on LLMs, but they're unavoidable. They've made some parts of my job easier, and they've made some parts harder. I still have to write a lot of code by hand because the LLM's code is often wrong.
sfpotter··on Mamdani Bans AI in NYC Schools
*moves back to NYC*
sfpotter··on A digestion of the Jacobian conjecture counterexample
The determinant of a polynomial mapping is a polynomial, which is the subject of the conjecture. To get the Jacobian determinant, all you need to do is compute partial derivatives of polynomials, and add, subtract, and multiply them together. All of these operations map polynomials to polynomials.

The crux of the assumption is that if a polynomial mapping is invertible everywhere (Jacobian nonzero everywhere), its Jacobian must be a constant. Why? Because the only polynomials which are zero nowhere are constants.

sfpotter··on A digestion of the Jacobian conjecture counterexample
No. This is about polynomials. The assumption that the Jacobian is nowhere zero is what is doing so much of the work. This means the Jacobian must in fact be constant. But obviously there are many mappings whose Jacobians are not constant.
sfpotter··on A Forlorn Hope of Fortran Modernisation
"At present, no language can rival, let alone surpass, Fortran when it comes to implementing long-lived, large-scale, massively-parallel scientific and engineering applications; not even C and C++."

Huh??? A tremendous amount of scientific computing happens in C, C++, and many other languages. I have worked with Fortran, worked with Fortran-heavy labs in academia, and this is just a nonsensical thing to say.

sfpotter··on Artificial intelligence is not conscious – Ted Chiang
So far as we know, consciousness only takes place in biological organism. A computer isn't a biological organism, therefore the burden of proof for claiming that an LLM is extraordinarily high. To me, this makes it reasonable to dismiss the idea. If you want to demonstrate that LLMs are conscious, you better start working on your neuroscience and philosophy PhDs.
sfpotter··on Nobody understands the point of hybrid cars [video]
There's a reason so many cab companies have fleets of Priuses.
sfpotter··on Coffee doesn't just wake you up–a biological pathway illuminates health effects
"Serious delirium!"
sfpotter··on I'm done making desktop applications (2009)
He didn't pooh-pooh anyone's careers.
sfpotter··on Legibility Is Ruining You
"Legibility" here just means something that is visibly important/useful/scrutable/not a waste of time to (i.e. "is legible to") a manager.
sfpotter··on Hamilton-Jacobi-Bellman Equation: Reinforcement Learning and Diffusion Models
This is what the field of numerical analysis exists for. These details definitely have been treated, but this was done mainly early in the field's history; for example, by people like Wilkinson and Kahan...
sfpotter··on Slicing Bezier Surfaces
This is just subdivision of Bernstein polynomials. The unifying way of looking at this is via the blossom of the Bezier curve (Bernstein polynomial). You can derive all manner of shifts, change of basis transformations, and so on using the blossom. Subdivision is just a shift of the domain of definition of the original polynomial.
sfpotter··on Enhancing gut-brain communication reversed cognitive decline in aging mice
It could easily be both.
sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
The truck would come by once a week to pick up all of our dirty diapers and drop off a new set of clean diapers. The service provided a bucket with a cloth bag inside of it that had enough capacity for one kid for a week. Packaging up = closing the lid of the bucket and leaving it outside the door of our apartment. They would drop off a new one of these buckets full of clean diapers each week (visiting many other people at the same time). Beyond all the environmental benefits, living in the city this was actually super convenient.
sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
With the service we used, they picked up and dropped off diapers once per week using a big truck. They also drove around to do the same for many other people at the same time. You can't call this diaper delivery "constant". And if the emissions from this are significant, you could always use an electric van.

How are you feeling: do you still think this is something only for performative environmentalists or "trad wives"? Neither of these descriptions apply in even the remotest sense to my wife or I.

sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
What do you find confusing about the idea of a diaper service? It seems too unsanitary for you? The idea that it might cost slightly more than disposable diapers is intolerable to you?

Do you have any reason to believe washing diapers actually is unsanitary?

sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
The energy saving is clear and gets better year after year as the grid continues to green. You can also line dry cloth diapers which saves a lot of energy.

I never had any trouble with cloth diapers. You can always have a blow out with any diaper, but I didn't have any issues beyond that. Of course, there's some technique, but it's easy enough to find a YouTube tutorial if you need it. Snappies and decent covers help.

sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
They really do! Anyone who's thinking that a set of cloth diapers begins and ends with a single family has really got a pretty limited imagination.
sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
Cloth shopping bags are a really bad comparison here.

Some things working in favor of cloth diapers here are general greening of the grid, mitigating issues with electricity consumption.

Beyond that, line drying diapers works very well and even preserves the life of the diapers.

Cloth diapers hold their value extremely well and can easily be bought/sold/given away on sites like OfferUp or groups like Buy Nothing.

ALso, "2 car trips per week": do you have no idea how this works? No diaper service in their right mind would send out cars to make bespoke trips to individuals. They're done using a big truck on a schedule to amortize the cost of pick up and drop off as much as possible.

sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
This study has issues. Take a closer look at it. See my other comment on here responding to someone else who linked to it.
sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
This study has serious methodological issues. I would encourage you to carefully peruse it yourself before citing. This is far from the only issue, but the fact that someone who works at Procter and Gamble is on the study's advisory board is... fun.
sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
Oops, talked to my wife and realized I got a detail wrong: we did not keep the diapers from the service, we gave them back. And the diapers we got from the service were almost surely used by plenty of other people before.

Someone else on here seemed confused about the logistics off the service. We lived in Brooklyn at the time. A big truck would drive around our neighborhood and pick up and drop off diapers from many people throughout the neighborhood at once. More amortization at work.

Also, one more thing: we're big on line drying. We will primarily line dry these diapers instead of drying them in a machine.

Oh, and one MORE thing: we got our current washer and dryer free from a friend who was about to throw them out when replacing them.

There are so many ways to mitigate and reduce environmental impact beyond the simple-minded apples-to-apples comparison many in this thread seem to be doing.

sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
We kept the diapers from our diaper service and the covers. The washing machines used by the service are much beefier and can handle these kind of loads easily, and will generally be more water efficient.

We also got a good number of used diapers on Offer Up.

When we're done with our diapers, we will rehome them instead of throwing them out.

How does this change your calculations?

sfpotter··on How Big Diaper absorbs billions of extra dollars from American parents
Cloth diapers are good. We used them for our last kid with a diaper service and are going to do it again washing them ourselves with our next who is due at the end of the month. Regular diapers are useful to have either way. But cloth diapers are obviously much better for the environment and if they're an option for you, you should consider them. Not a hard concept, not worth a big discussion.
sfpotter··on Bourdieu's theory of taste: a grumbling abrégé (2023)
He sees through his beer purchases but he doesn't see through his seeing through them.
sfpotter··on Woxi: Wolfram Mathematica Reimplementation in Rust
What? Arbitrary precision arithmetic implemented in a compiled language will be faster than the alternative. This is no great mystery. The same is true of essentially all low-level symbolic or numerical math algorithms. You need to get to a fairly high level before this stops being true.
sfpotter··on What is f(x) ≤ g(x) + O(1)? Inequalities With Asymptotics
The reason it's preferred to use "=" instead of "\in" is because the way that Landau notation is generally used in practice is as a kind of ellipsis or placeholder. For example, the Taylor expansion e^x = 1 + x + O(x^2). I could just as well write e^x = 1 + x + ..., but the former conveys more meaning about what is hidden behind the ellipsis. It's an abuse of notation, but in the contexts that it's used, it's not clear what additional clarity using "\in" would bring over "=". Maybe also that big O is mainly used as a notation to facilitate doing calculations, less describing what family a function belongs to. Here are Knuth's thoughts, which I agree with: https://micromath.wordpress.com/2008/04/14/donald-knuth-calc...
sfpotter··on Ask HN: Burned out from tech, what else is there?
Why are you asking HN? Do you have anyone you know in your personal life you can talk to? Family or friends? Hopefully someone you know well can give you some honest feedback and help you figure out what would be a better fit for you. I don't see how a bunch of strangers on HN could possibly help seeing as they know nothing about you and totally lack context.
sfpotter··on Cadova: Swift DSL for parametric 3D modeling
You're in luck! As of a year ago, I work at McNeel on the math team on Rhino's in-house CAD kernel. Luckily, we own the entirety of the kernel, so we are free to improve it. I've been in the field of numerical methods for most of my career in academia and industry, so you are preaching to the converted when you say that Rhino's numerics are mediocre. At McNeel, I'm actively pursuing strategies to improve this situation, although it will be a massive long term project.

Hopefully you know that you can reach out to the McNeel developers directly and on the Discourse forums. But I would also love to chat directly if you're interested. It sounds like you're working on a project that is both sophisticated and interesting, which directly stresses many of the known pain points in the kernel. If you're interested, I can shoot an email to the address you've got listed in your profile from my McNeel email.

Page 1 of 23Next →