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rf15

2,269 karma · joined June 15, 2017

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rf15··on A new faster algorithm to compute 64-bit signed floor division
I found this by accident because I wanted to speed up a part on my Pebble watch face, I didn't even know the history of past attempts. The floor variant was born out of a particular rounding optimisation attempt that felt like it could be easier if I just use floor/ceil and moved it into a large int-multiplication space. (this is very tempting because certain constants for rendering and angle calculations are based around large integer constants on that platform, kinda doing half the work towards this idea by creating this particular constraint)
rf15··on A new faster algorithm to compute 64-bit signed floor division
> As you can see, the technique is so simple that I'd expect that somebody has done this before, but I've looked around and not found it documented anywhere.

I'm one of those people I suppose. Yes, if you want to play with microoptimisations and part of a calculation are known, you can flip a division into a mult (and shift).

This might seem somewhat useless at first, but you can use this to e.g. speed up calculations in nested loops, where you can precompute this for relevant loop-layers.

rf15··on Wealth Inequality in America drawn to scale
This is about wealth inequality, i.e. how far the scale is leaning. This has, as the website explains, some funny effects: looking from the top, you are effectively starving the people that pay you and your descendands. That might work for a few years, but if everyone's hungry it's gonna be heads on pikes no matter how many bunkers you build and how much you pay for personal protection.
rf15··on Diamond Transistor
> It's still the hardest material we have measured.

Can't believe this statement hasn't caused other nerds to crawl out of their holes to correct it yet, so here I go: acshually...

We know about Lonsdaleite, which packs its structured in hexagons rather than the usual cubic forms of diamonds.

... too bad its natural occurance is always somewhat spoiled and it doesn't reach its full potential in nature in any meaningful size, as far as we could observe.

rf15··on I will no longer upload to NEW
... in pink on yellow too, if you add a color picker.
rf15··on A Man from the Future: Why Johnny Can't Stop Abstracting
That's sadly impossible, because the brain, as a limited number of cells, cannot store infite data. The problem lies in the people observing them, but you have some fun mechanisms (and a few of the commonly known fallacies and biases) at work here, that can all contribute to that perceived effect/illusion. Consider the following ideas:

- people can be slightly better than a given random observer, because they learned and prioritise to pay attention. They are better at recalling memorable and minor details, especially in short term memory and in memorable situations that a lot of people share long term. They will still forget long term information that is irrelevant.

- any such person and also observer can easily talk themselves into the belief that their skill must be absolute, especially since the observer will largely only test from his own inferior dataset.

- once the belief takes hold (because people love a good story), observers tend to look less for flaws and more for further confirmations to keep mythologising people.

rf15··on Lula wins election after final votes tallied
Yes, both asked for it. Didn't stop Jair's son to call it "unprecedented"
rf15··on Meta employees say Lula’s accounts restricted in Brazil election: Report
No, it's the lawnmower analogy again: Zuckerberg has no political views, he just thinks that Trump will restrict him less/allow him to make more money/is easier to exploit.
rf15··on Elon Musk Acquires $1B Stake in CNN's Parent Company
Washington Post moment, I'd expect. The information space around the next election will be crazy. State of emergency and president for life, anyone?
rf15··on Local Wikipedia: Wikipedia, but only for things a half hour walk from you
Check out what slymax and esperent wrote in another comment[1].

You can let it pick your own location, and if you rewrite the language prefix at the beginning of the url, you get that language's version. [2][3]

[1] https://en.wikipedia.org/wiki/Special:Nearby#/coord/15.90721...

[2] https://fr.wikipedia.org/wiki/Special:Nearby#/coord/15.90721...

[3] https://es.wikipedia.org/wiki/Special:Nearby#/coord/15.90721...

rf15··on This I Believe (1952)
Ah, Heinlein. There's not much energy up there, and the energy question is a big one. It's now 2026 and we are still at the point where we can only move a fraction to actual space of what we originally start off with down here. Our fuel is still not anywhere close to what we'd need in terms of energy density and throughput.
rf15··on Every AI model has the same "controversial" take on humans
additionally, probably strong overlap in training data
rf15··on Why America Hates the Billionaire Barons of Big Tech
This is from Robert Reich, former secretary of labor under Clinton. He is still very much politically active.
rf15··on There isn't an easy exploit for this PHP vulnerability
> Ease is irrelevant because you only need expertise once and then everyone can reuse the result.

Not if your LLM relies on existing code and you collectively create a million repos with hallucinated broken implementations that do not work before a good public exploit exists, which later LLMs rely on. LLMs are self-defeating that way.

rf15··on There isn't an easy exploit for this PHP vulnerability
Culture? In MY internet?
rf15··on There isn't an easy exploit for this PHP vulnerability
Yes, but the same is true about LLM output. Guess there's actually no way around this than to go look yourself.
rf15··on Android apps running native on macOS
> they store the data in the user home folder.

that's a very dishonest or at least inaccurate depiction considering the multiple, semantically confusing places app data can be stored on win/linux

rf15··on The obscure trust looming over Anthropic's IPO
That also kind of implies to me that they had the foresight to know that this is probably not a good investment on paper but still wanted to surf the hype wave
rf15··on Java sealed classes and exhaustive pattern matching
No, I assert that the concept as defined has a reasoning behind it that accepts certain tradeoffs for certain benefits. I think its perfectly valid to disagree with them, but I am curious about improvements to the current solution to the problem of extending types that really should not get extended (e.g. from the standard lib)
rf15··on Java sealed classes and exhaustive pattern matching
Yes and no. You either accept that your code and the environment is final (in which case there's no problem and you can just blindly use the exhaustiveness check) or you accept that your code is a living thing that can change in part (including your edits, its dependencies, and its standard library), in which case you must be prepared for changes but can still make use of the exhaustiveness check by temporarily removing the default case.

I feel this is fundamentally a perspective issue. If this is a problem, also consider why people want sealed classes in the first place. It's always a tradeoff and you can also always fork or propose your own improved version of the concept and see if it has enough merit to gain traction. There's a million other footguns in the language that needs similar scrutiny, I'm just happy java isn't C/C++.

rf15··on Java sealed classes and exhaustive pattern matching
I disagree - the problem lies with the intention of exhaustively listing all available values in a switch expression with no backup plan. Switch expressions should always have a default/fallback branch, even if it's theoretically impossible and only logs the attempt/picks a default for future proofing the code and its uses.
rf15··on Weak Links Start to Show in A.I. Borrowing
> The broader question is whether companies facing debt trouble like CoreWeave, Oracle and SoftBank are the industry’s weak links or are harbingers of deeper problems in the A.I. build-out.

What's a little circular dealing among friends anyway, surely there wouldn't be more to see here...

Anyway, happy to see reality adjusting itself.

rf15··on Microsoft Teams is a red flag
In our european company (insurance/gov space) we use Teams, Outlook, Sharepoint as side products of Office, largely to get the official editing tools for the documents our clients provide. Depending on who you are in our company, you are using either Mac or Windows, although we are slowly shifting to OpenSUSE. Azure and GitHub are completely out of the question, and OneDrive is only used in the context of Teams/Sharepoint. Sharepoint, too, is only used by half the company for whom it is relevant.

Security-wise most of our data is with our customers on european servers (Word/etc. are not linked to OneDrive), except billing.

rf15··on Gnome OS Preview
That is a very fair assessment I feel. Also there's nothing wrong with being confrontational, we will not thrive on uniformity.
rf15··on How to Formalize All of Mathematics
As a kid I learned the basics of programming in primary school before learning any math notation beyond the absolute basics. Programming was:

- a strict, limited syntax to lego complex ideas together

- strictly one-dimensional (characters/words in lines)

- variables were written with the intention to speak their semantic role

Coming to math beyond primary school was hilariously emotionally challenging:

- A simple sum described with a sigma symbol: "What? why are you writing all over the place for a simple for-loop or reduce operation? why a specific symbol at all for a trivial +-aggregation?"

- having to help a first year math university student with finding an algorithm to a number packing/division problem: "nobody teaches data structures or dataflow despite the fact it would make things very much easier for everybody?"

- variable 'a', 'b' in complex formulas: "What happened to you? Does your parent not love you? why are you a faceless goon in a sea of other symbols? Stormtropper-ass naming attitude smh. Also making things harder on the reader to digest the algorithm you actually want to talk about so you can be lazy with your pen"

- "Is any old Tom, Dick or Harry just making up multi-dimensional symbols here for every micro algo they come up with?!"

My math skills are okay now, since university was littered with just verbal formal definitions, which made everything easier. From day one I was yearning for a more unified formalisation of everything that was shown to me (or even competing universal formalisations, like in programming languages!), especially since Mathematics seem equally defined by the found insights as it was by the idiosynchracies of the researcher and the math community as a whole. I dreamed of getting the culture out of math, to relieve it from that "impurity" and make it more like my experience in programming, where a basic algorithm could be understood in the abstract and ported to a variety of languages/abstractions/formalisations.

Anyway, that was a kid's dream. Am I better now, team lead at some software company and teaching yyounger people programming and math in my spare time? Nah, I still look at everything with eyes of "How can this be improved?", just the "looks like rubbish to me" attitude has marginally come down.

rf15··on Gnome OS Preview
> Gnome is notoriously 80% everything you ever wanted in a desktop environment

their pivot from highly customisable kde-like experience to look more mac-like actually dropped that 80% towards 0 for me.

Also, fundamentally: for a Desktop ui to ask by default for more than one bar to stick into your desktop space is just greedy.

rf15··on Tesla Roadster
A silent (and yet so noisy) cry for attention?
rf15··on Tesla Roadster
I too solve my problems by getting catapulted multiple feet in the air without a clear landing plan
rf15··on Meta’s new commercial terms will allow the scraping of news sites: experts
The biggest magic trick of the people that make the world burn is to convince themselves that it's not worth looking out the windows of your home.
rf15··on Meta’s new commercial terms will allow the scraping of news sites: experts
well arguably they are still trying to wrestle with theorising what they can get away with, so there are clear limitations.
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