lambdaone

Mesh radio bandwidth is pretty poor. Firstly, you have to compete with many interferers (albeit this might get better if the power goes down), including other LoRa radios, but more to the point, long-distance connections consume bandwidth and aquire delay and delay variation at every intermediate hop. It might be reasonable to use it for text messaging, but with per-hop bandwidth ranging from 0.3 kbps to 27 kbps, which will get divided down further over shared multi-hop links it will be impractical to use it for anything else except perhaps very-low-bandwidth telephony over short distances or visiting minimalist text-only websites.

It might make more sense if augmented by fixed multi-megabit point-to-point microwave radio links to act as a backbone, with LoRa only functioning as an access network.

I'd be interested to hear what experiences people have had with doing this for real.

It's substantially harder than linear programming: it's equivalent to SAT, whereas linear programming is merely polynomial-time (and in practice weakly polynomial-time with current algorithms).

HyperCard was undoubtedly the inspiration for Visual Basic, which for quite some time dominated the bespoke UI industry in the same way web frameworks do today.

It allows the Mac to use far less RAM to display overlapping windows, and doesn't require any extra hardware. Individual regions are refreshed independently of the rest of the screen, with occlusion, updates, and clipping managed automatically,

They don't create contiguous surfaces, and GPUs are optimized to deal with sets of triangles that share vertices (a vertex typically being shared by four to six triangles), rather than not shared at all as with this.

"Watertight" is a actially a stronger criterion, which requires not only a contigous surface, but one which encloses a volume without any gaps, but "not watertight" suffices for this.

"Overly strict" only leads to ossification if the designers of the system forget to build extensibility into their system design from the beginning.

Postel's law is absolutely great if you want to make new things and get them going in a hurry, and I think it was one of the major reasons the TCP/IP stack beat the ISO model. But as you say, it's a disaster if you want to build large robust systems for the long term.

Not really, unless you have thousands of routes to manage across large numbers of gateways. Otherwise, running BGP inside your homelab is just a learning tool.

In the "real world", techically competent people understand decibels just fine.

But this is not arcane knowledge only known by a priesthood. Since you are clearly confused about what a decibel is and how and why it is used, you can read

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

and all will be revealed.

It's a bit like hating numbers, and saying "What do you mean by 'three'; what is it - three volts, three amps, three metres? Clearly 'three' is meaningless, and we should stop using it and all the other numbers besides."

decibels are simply a dimensionless ratio, used as a multiplier for some known value of some known quantity.

In every context where decibels are used, either the unit they qualify is explicitly specified, or the unit is implicity known from the context. For instance, in the case of loudness of noise to human ears in air, the unit can be taken to be dBA (in all but rare cases which will be specified) measured with an appropriate A-weighted sensor, relative to the standard reference power level.

And similar (but different) principles apply to every other thing measured in dB; either theres an implicit convention, or the 0 dB point and measurement basis are specified.

People who assume that everyone is an idiot but themselves are rarely correct.

I look forward to the author discovering about (for example) the measurement of light, or colorimetry, and the many and various subtleties involved. The apparent excessive complexity is necessary, not invented to create confusion.

Why should floppy disks be a problem? Even if they are fantastically out of date, if they can be maintained as a niche legacy technology, they're not a problem. They won't suddenly stop working, it will just slowly get more and more expensive to get the parts. Supply chains are magic - at the right price, someone will always be willing to make more floppies or drives. Of course that price might be $500 per floppy and $50,000 per drive...

Even though it might seem unlikely, you absolutely can't eliminate the possibility of planes falling out of the air unless you have thoroughly audited and tested all their systems in advance. Not having planes in the air at the exact moment of rollover - just in case - might be a good idea too. Similarly financial markets and other key infrastructure.

13 years is plenty of time to make a start on all of this, and will allow the costs to be spread over that time period without undue hurry. It's also long enough that it will be possible for much software to be allowed to reach end-of-life without being audited, while applying rigorous testing to new software. Procrastination, though, is not a good option.

It means 'anywhere between being bricked and no problem at all, and we can't give you any idea of how severe or how likely any of those possiblities are'. The only way you can really know is to thorougly audit your system and/or test it. Preferably both.

Unironically giving that prime number routine as an example of clever code is not a great look. So bad on so many levels.

Most users don't know what io_uring is, nor would they have read any of thosee articles. They are not HN readers with low-level understanding of operating systems workingm and don't even remotely have the knowledge of how any of these technologies work, nor do they have the time to get it. With a very few exceptions, users have to rely entirely on software vendors and service providers to do this for them, and trust they know what they're doing.

A side-note: I have a friend who is an electronics genius who managed to construct a production system that combined a multi-kilowatt electric arc lamp and a CCD array. Microvolts of CCD signal at megahertz of bandwidth mixed with hundreds of watts of RFI all in the same chassis. Oh, and of course lots of low-jitter digital timing and sequencing electronics and wideband ADCs.

It all worked perfectly. He used every trick in the book, and some new ones he invented from scratch, to implement it - I've never seen anything like it, before or since.

Real environments have both mechanical bouncing and unavoidable EMI spikes, even when you have done your best to eliminate EMI; particularly when you're dealing with switches, which are typically on the end of long wires which are effectively antennae. Source: actual experience with crappy real-world systems.

A bit of analog low-pass filtering and electrical hysteresis definitely helps reject EMI - but you shouldn't use these alone to do debouncing as if you do, you introduce substantial latency for both up and down transitions. The (very simple) software algorithm described above gives you both low latency and complete resistance to bouncing. Combining the two is a complete solution.

The system is hit so violently that it goes into a non-linear regime, repeatedly hitting the end-stops of its motion. Consider how adding even a small amount of nonlinearity to a simple harmonic oscillator can create chaos, and I think you should be able to see how this generates chaos.

Doing it right (via the algorithm above) is a trivial few lines of code. The thinking behind the state machine that gives both high reliability and low latency isn't trivial. It is, however, obvious once you know the trick of maintaining an extra auxiliary variable in addition to counter/timer variables, and understand that you don't need to wait for the bouncing to finish before registering a change. Think sort algorithms; everyone comes up with bubblesort first, but you can do much, much better with only tiny changes after a bit of thought.

I do something very similar, but use two time constants. One to determine how many consecutive samples are needed to change from the established state, and a second one, as suggested here, to ignore subsequent input for a bit after a registered state change to allow for bouncing before going back to the receptive state. This is a bit more robust, as practical systems are always at the mercy of occasional glitches in electromagnetically noisy environments.

With well-chosen constants, I've found similar behaviour to the above; low latency and high performance at once.

Perhaps a glimpse at the atmosphere of optimism at the time of Musk's pushing of FSD?

For large polynomial degree, this seems to me to be very similar to the P-spline method with a very large number of parameters.

Self-experimentation! Excellent.

This is one of the things I was talking about when I said "simplifying".

That's exactly their motivation, yes. Resisting it requires political will, or we will continue to let the increasingly irrelevant tail wag the dog.

There is definitely a case for subsidising the existence of mostly-idle gas plants to make the costs of keeping them around profitable for the medium term (you can think of them roughly as playing the role of a battery), but indefinitely subsidising the equivalent of buggy-whip manufacturers is not a long-term solution for the economy.

Below the Planck distance, "closer" ceases to be a meaningful concept. Similarly, distances larger than the size of the observable universe may also be meaningless.

One thing which has not been mentioned in this discussion is that the wholesale market price of power at any given time is substantially driven by the marginal cost of generation.

When renewables (including storage) can't take up the entire load of the system, that marginal generation is nowadays going to be gas power, and right now the global price of gas is unprecedentedly high.

To simplify things somewhat; the larger the fraction of the time gas generation can be turned off, the lower the annualised price of electricity will be. At the moment, we are already seeing renewables taking up 100% of the load for short periods. As more renewable capacity gets built, those periods will get longer and longer, this effect will get ever larger. In some countries this effect is expected to become significant within the next five years, even at current rates of progress, and will only get better as time goes on.

Lower annualised electrical prices will be good for the economy and the individual, and encouraging this should be a priority for any rational government which thinks more than a few years ahead.

My understanding of this is that P-completeness for a problem implies that any problem in P can be transformed into it with a polynomial-time reduction. Deterministic Turing machines (more precisely, the problem of determining the future state of a deterministic Turing machine) are in P.

So quite literally mains hum, at least in countries with 50 Hz systems, since the magnetostriction effect makes the second harmonic dominant.

Grid connection delays are an absolute nightmare in the UK. Among other things, it's holding up house-building and thus making the housing crisis worse. This is at least a start in trying to get to grips with the problem.