jdewerd

Joined 2 years ago

Karma
662
Submissions
171
Member since
Dec 8
My email is at the domain of jdewerd.com with username jon.
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Recent submissions

Comment · 6 months ago
Loads of games from the era roundtripped their textures through lossy S3/DXT compression and then stored them as uncompressed RGB or RGBA.

I know this because I wrote a Unreal Engine texture repacking tool with a "DXT detection" feature so that I wouldn't be responsible for losing DXT compression on a texture which had already paid the price, only to find that this situation was already hyperabundant in the ecosystem.

Many Unreal Engine games of the day could have their size robotically halved just by re-enabling DXT compression in any case where this would cause zero pixel difference. This was at a time before Steam, when game downloads routinely took a day, so I was very excited about this discovery. Unfortunately, the first few developers I emailed all reacted with hostility to an unsolicited tip from what I'm sure they saw as a hacker, so I lost interest in pushing and it went nowhere. Ah well.

Comment · 11 months ago
How long until it comes with a DRM AI and then my anti-DRM AI will have to fight it in a virtual arena (with neon lights and killer soundtrack, of course)?
Comment · 11 months ago
ISM is thriving, the only tragedy is that carriers haven't figured out how to charge rents on it and that's a tragedy for them, it's a spectacular success for everyone using it for free.

Carriers don't need 6GHz for backhaul. They have fiber and cable and (other) microwave. Not to mention the ability to shape their own links with antennas and beam forming and do a good job of it rather than a "default job." What they don't have -- and shouldn't be given under any circumstances -- is the excuse to build a moat in the bustling public park.

Comment · 11 months ago
Completely independent of bandwidth, higher frequencies also fall off faster. That's bad if you are trying to cover max space but good if you are trying to avoid noisy neighbors.
Comment · 11 months ago
I never said anything about free or government-run WiFi, just about auctioning off the spectrum. Companies that build out the infrastructure should be able to charge for access, but they shouldn't be able to prevent others from competing by paying the government for exclusivity. That's a scam.
Comment · 11 months ago
The most efficient way to extract money from people is to sell off the spectrum to the highest bidding rent seeker, I agree.

As for most efficient use of the resource, well, consulting my spectrum analyzer, ISM bands are winning by a mile and we should want more of them.

Comment · 1 year ago
Is that because defense doesn't like them or is it because (non-wartime) defense moves on geological timescales and these are "new"?
Comment · 1 year ago
Yes, but the more we mix sieve rejection into candidate selection the more we complicate the rule of thumb. "Reject even numbers as prime candidates" is probably OK to leave as an exercise for the reader, as is the equivalent "round every candidate to odd" optimization. The point about random vs sequential is well taken, though, and it doesn't complicate the rule of thumb, so I changed it.
Comment · 1 year ago
Yes, excellent point! I originally omitted this detail for simplicity, but on reflection I don't think it actually achieved much in the way of simplifying the rule so I changed it to reflect reality. Thanks for pointing that out.

EDIT: the rush of people offering up sieve optimizations is pushing me back towards formulating the rule of thumb on a consecutive block of numbers, since it makes it very clear that these are not included, rather than implicitly or explicitly including some subset of them (implicit is bad because opacity, explicit is bad because complexity).

Comment · 1 year ago
> The prime-counting function approximation tells us there are Li(x) primes less than x, which works out[5] to one prime every 354 odd integers of 1024 bits.

Rule of thumb: Want a 1024-bit prime? Try 1024 1024-bit candidates and you'll probably find one. Want a 4096-bit prime? Try 4096 4096-bit candidates and you'll probably find one.

The approximate spacing of primes around p is ln(p), so ln(2^1024) = 1024*ln(2), and ln(2)=0.693 so if you are willing to absorb 0.693 into your rule of thumb as a safety margin you get the delightfully simple rule of thumb above. Of course, you'll still want to use a sieve to quickly reject numbers divisible by 2, 3, 5, 7, etc, and this easily rejects 90% of numbers, and then do a Fermat primality test on the remainders (which if you squint is sort of like "try RSA, see if it works"), and then do Miller-Rabin test to really smash down the probability that your candidate isn't prime. The probabilities can be made absurdly small, but it still feels a bit scandalous that the whole thing is probabilistic.

EDIT: updated rule of thumb to reflect random candidate choice rather than sequential candidate choice.

Comment · 1 year ago
Oh, he only busted the Great Depression, won WWII, built half of the infrastructure that we keep kicking the expiration date on, and negotiated 80% of the beneficial fine print in your employment contract. Don't you think he could have done a bit more?

My list would be: 1. FDR, 2. Carter, 3. Teddy. Carter because he sacrificed his career to fix inflation (Republican attempts to rewrite history notwithstanding), and Teddy because he wasn't merely an excellent man with excellent politics, but also because whenever present-day Republicans try to claim the man without claiming his politics I can turn it into a teachable moment, and putting him on a list with the other two is the perfect bait.

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