I love penny smashers. I have a paradoxical attitude toward souvenirs: on one hand, I like to have reminders of places I've visited as well as a physical token of "proof" that I've been there; on the other hand, I hate household clutter and don't like to spend money on what amounts to junk. Penny smashers fill a perfect role. They are literally a token of proof that I've been to a place, while also taking up almost no space and being very cheap.
Cats are crepuscular animals. They are "programed" do start at 5 AM, hunt, and go back to sleep until afternoon. Living in homes tweaked them a little, but the 5 AM thing is still strong in a lot of them (mine included).
So not specifically at 5AM, but around twilight. In my area, and for my cats, that changes a lot between summer and winter.
Same for my chickens, which is why "automatic chicken doors" are difficult/impossible around here: It'd need to calculate sunset and sundown, and then also consider clouds and trees: in winter the sun sets around 16:30, but the low angle makes sunlight more blocked by clouds, particles and trees and such. My chickens often decide its bedtime before 16:00 already.
The automation features in Apple Home can be set to do things at sunrise or sunset. These track down to the minute the sunrise/sunset times from the weather app data for your location.
Your best bet, if you really want an automatic chicken door, is to get a dumb one that just opens when powered on and closes (via springs) when powered off, then plug it into a smart outlet automated to turn on at sunrise and off at sunset.
I wonder if a motion sensor detector would make the last mile of it more precise, as soon as a chicken wakes up just open the doors idk (if on timeframe)
Are you crazy? Just get an LLM into the decision loop and you can obviate the need to iterate and test with a lazy human brain and instead waste a fabulous amount of energy, all while setting your project up to get some fat VC …
Automated chicken door isn't too difficult; remember the goal is to allow them to come in or out, not to make them do so or wake them up, though they do get conditioned to the door opening.
I made mine to open at actual sunrise (except in the summer; I keep them in until 7am because the coop is cooler, and if let out they can get loud before my neighbors wake up) and close it at actual sunset (not civil twilight, which most people think of when you say "sunset"). Generally the door is open well after the birds are in bed, which is fine.
Aside from some dumb birds when they were younger, I've never had one locked out (and those dumb ones were trying to nest in silly places, and weren't going you come in no matter when I closed the door).
When I did it, I closed the door at nautical twilight. The key is that you need to close the door after the chickens roost but before the nocturnal predators come out.
Yes. We used to have these. And i turned it to most conservative twighlight.
It worked most of the times, until in winter, twice, some chickens were locked out. First time I saw it in time. Second time I only found feathers the next morning and one chicken less in the coop.
While on an especially cloudy (snowy) evenings, the door would be open when it was almost pitch dark out there and I caught a fox near already.
"The Real World" is just messier than a mathematical representation can be.
I use https://sunclock.net/ and have built a watchface like that for my fitbit like that. The mathematical model is perfect as guidance. But it's not reliable enough to bet the lives of my chickens on it.
When I had cats, I couldn't leave the bedroom door wide open, because that would give them space to come running into the room and jump onto the bed (sometimes on my face) at early hours.
To complement the treat rewards, can you get the cat wheel to power a small pump to provide a water fountain for the cat?
Assuming the treats are dispensed after a variable amount of distance is travelled on the cat wheel (to turn your cat into a 'gambler' of sorts, thereby keeping your cat on the wheel in the hope of a treat), a water fountain with 'fresh' water should enable your cat to avoid dehydration (due to the excessive exercise, chasing treats).
Harvested energy could also power a fan for the wheel and/or a heat pad in your cat's bed.
With these improvements, those short jogs will inevitably become marathon runs.
Always hard to be sure, but I think so, yes. The dispenser is only triggered when he runs either fast enough or long enough (I forget the thresholds, but it's something like 10 mph or 10 seconds). Sometimes he'll run and not quite trigger the threshold, but wait next to the dispenser for the treat to come out. When it doesn't, he'll go back to the wheel and run/walk for a much longer period.
As a former rabbit owner I can attest that around 5 am was when the theater would open, and the first thing on was always this improvised bit called “abused animal trapped forever in a cage”. Lots of special effects too, there was gnawing and rattling and stomping. When I did open the cage door, she would jump out, take a look around and happily go back to napping right there in front of the cage.
This just plugs into an outlet and offsets whatever usage you have, though. No need for a battery or matching load. It just subtracts 180 watts from your household usage.
These types of devices are fairly popular in Germany, and maybe other places. For someone like me, with very high peak daytime prices, even a small offset would be valuable, but the full price here seems to be $500, which is too much. No reason it couldn't be much cheaper, though.
Call it 200W, and it would offset say 5 hours a day of that for where I'm at.
Call it 1.5kwh for the entire day being optimistic. This would save me (inclusive of taxes, etc.) roughly $.33/day. Call it $10/mo.
34mo so payback isn't the worst I suppose. Better than I expected to be honest. Probably not worth the hassle factor though since I don't have an ideal place to put such a thing.
I do have an "always on" load of well over 200W in my home, so at least it would offset every watt it generated. I'm not sure how true that is for most folks, as most folks don't run a home lab in their basement.
Are you at least a little familiar with linear algebra?
If so, you've probably heard of the determinant. It's a certain way of "summarizing" a matrix with one value.
The determinant in this case is of the Jacobian, which is a matrix you can construct from a multi-variable function. Each term is the partial derivative with respect to each variable (x, y, z, etc.), with one line per output variable (vector element).
The Jacobian of a polynomial function is, in general, going to be a matrix where every term is some polynomial expression. And the determinant of that will also be a complicated expression. But in some cases all the variable terms cancel out and you're left with a single constant (0 or some other value).
The conjecture says that if the Jacobian determinant is constant (i.e., all the terms cancel out), then there must be a polynomial inverse. And the key condition for an inverse is that there must not be two input points that evaluate to the same output. It's just like y=x^2. It's not invertible, because both +2 and -2 square to +4.
So if you can find a function where the Jacobian determinant is constant and also find two or more points that evaluate to the same output, then you've found a counterexample to the conjecture. And that's what's been done. And remarkably, the counterexample is pretty simple. It would be tedious but a bright high school student could verify it.
I think another way to understand it is the generalization of the inverse function theorem. The inverse function theorem gives you local invertibility, but even being "locally invertible" everywhere does not imply global invertibility (you don't need too pathological an example to see this, a periodic function serves iirc).
The Jacobian conjecture roughly asks what whether local invertibility gives you global invertibility when you restrict only to polynomials (which we might hope "behave nicely"). Apparently for polynomials over reals this was disproved a while back, but up until now the general case of polynomials over complex numbers was open.
Thanks, though I realize (thanks to tptacek) that I didn't properly emphasize that the determinant must be constant but non-zero.
If the determinant were zero, then (for basically the same reason as why you can't divide by zero) the matrix wouldn't be invertible. You wouldn't expect the polynomial to be invertible in that case, either.
If the determinant had free variables left over, then there is some combination of variables that will make it zero (e.g., if it came out to x^2-1, then it would be 0 for x=1 or -1). So maybe inversion won't fail everywhere, but it will fail in those spots, which would also lead one to think the polynomial is not invertible.
But if it's constant and non-zero, then there is no place where you can't invert the Jacobian. So it seems very plausible that this would apply to the polynomial as well. That's essentially what motivated the conjecture in the first place (leaving out some details, of course).
As others said, you can run more than one at a time, but even singly, 24 GB can be very useful in a hybrid approach. For instance, I recently had to process hundreds of high-res blueprints. Used Fable for the main orchestration, but all of the OCR and other work I did with a small local model. Didn't waste expensive Fable tokens on simple grunt work.
Movie-Nedry struck me as a certain kind of hacker trope (but whom I've also met in real life!) where part of their "compensation" is access to unusual and high end computer hardware. It's irrelevant whether it's the best tool for the job (and as the page notes, Nedry seems to use his fancy SGI system mostly to render 3D chess). But, at least in principle, it's relatively cheap payment to keep your programmers happy (though it didn't exactly work out in the movie).
I don't think that it makes much economic sense. That hardware was extremely expensive at the time, developer salaries weren't as high, and hardware progress was extremely fast, so the computers had to be replaced every two or three years to remain practical, not just cool.
No. And in fact it annoys me greatly that our work IT department forces a reboot once a month.
My desktop is like an actual desktop. I have my tools laid out exactly how I want them for the task I'm working on. I want to come back to them in exactly the same place when I pause for the night or weekend.
I have to clean it up occasionally, to close out things that I'm no longer working on or forgot about. But I'd rather do that incrementally than all at once. Forcing a reboot is like tipping over a physical workbench with a bunch of tools and in-progress projects on it. Just awful, and often takes hours to set back to its original position (at least browser tabs restore reliably these days).
This whole time I thought IT keeps sending out those emails about rebooting for updates because people just couldn't be bothered to remember otherwise. Turns out some remember very well, they just don't care!
sounds like some software projects to work on, being able to reboot back to like exactly where you left off (I've been trying to figure this out more for my own computer)
Cheat answer: velocity is a vector, and can be negative, while KE is a scalar and has to be positive. Therefore you have to square v to get rid of the minus sign.
Why not take the absolute value? Nature hates those, probably because the derivative is undefined at 0. So squaring it is.
I like to think of it as dot product being the true "natural" space to compare magnitude metrics, whereas absolute value is just a human construct conceived for our mental convenience. A smooth parabolic bowl vs an unnatural sharp conical tip. Also shows up in standard deviation etc.
Aside: I wonder if complex values neural networks with activation function just being sum(inputs)*conj(sum(inputs)) with threshold normalized by sqrt(num_inputs) could be the most universal, where incoherent inputs will average an absolute value of sqrt(N) and coherent inputs are N like lasers? (square amplitude would be N vs N^2 between uncorrected and correlated population)
One way of thinking about that is higher order even powers just reduce down to two.
For the purpose of inverting a negative vector, you can think of squaring as rotating the vector around the unit circle, 180 degrees, to make it positive. Higher order powers just keep rotating that vector back and forth- from this perspective the other even powers are the same transformation. Obviously with the magnitude being different.
> Why not take the absolute value? Nature hates those
And yet inverse distance laws for potential energy for gravity and electric fields use the absolute value because they require an unsigned distance and how you treat the singularity at zero is extremely important to the structure of those interactions
Why isn't the shifter built with a log2 arrangement, shifting 32-16-8-4-2-1 bits? Takes fewer sub-stages and doesn't require a separate decoder for the input.
The article mentions it already has a two-stage design, shifting bits and then bytes, so it can't be about shifting more than one bit at a time. Anyone know why?
Yes, you can use a "logarithmic shifter". The CDC 6600 supercomputer (1964) used that approach. The tradeoff is that you need more stages with the logarithmic approach (six versus two for 64 bits).
If you're using MOS pass transistors for each stage, you lose some voltage at each stage, which limits the number of stages. I think this is why the 8087 (and the 386) used two-stage shifters rather than logarithmic shifters. I don't know how the circuit area compares between the two approaches--two more complex stages vs six simpler stages--but I suspect the two-stage approach wins.
CAD was a very incremental process. Early chips were drawn by hand and the Rubylith masks were cut by hand with the help of a Coordinatograph. Later, Intel used a Xynetics plotter to cut the Rubylith. By 1974, layouts were digitized with a Calma GDS I so repeated cells could be handled automatically. By the time of the 8087, there was a lot of automation.
You might think that the 8087's shifter would be a regular grid, easy to lay out by hand. It turns out to be very optimized and irregular. (I traced it out by hand and it was a pain.)
