2418 posts • joined 10 Jun 2009
I think the right way to view it isn't signal theory. It's that there is tension in the spring. When the top is released, it accelerates downwards at a greater acceleration than G, because it is also being pulled down by the tension in the spring.
For every action there is an equal and opposite reaction. At the bottom of the spring, the tension is pulling upwards, oposing gravity. And of course, the Earth itself moves towards the Slinky, by some unimaginably minuscule amount.
Re: Speaking of springs ...
It turns into heat. The atoms in a stretched spring are alightly further apart than they would be in an unstretched spring, and therefore there is slightly more energy in the inter-atomic bonds that are destroyed one by one by the acid.
A better puzzle is this one
You have a battery connected through a timer switch to an electromagnet. This is supported on a disk which is at rest but free to rotate on very good bearings.
The timer clicks, the magnetic field decays, the electromagnet kicks, and the disk starts rotating. Where did the angular momentum come from?
It's from the Feynman lectures (of course).
Re: I never could make my slinky work
I wonder how many miles long that Slinky would be, if they hadn't chopped it into lots of toy-sized pieces as it came out of the Slinky-making machine?
Procedural, Object-orientated, and Introspective
There's a lot of obfuscation out there about what is a very simple concept.
Procedural: F(a, b);
The advantage of the latter is that you cannot apply an inappropriate F to argument a, because only the methods of the object a are available in this context. It also reduces the number of pointers or object handles one has to keep track of. Of course, it doesn't prevent all bugs. You can still do (say) a.clockwise(b) when you meant a.anticlockwise(b) or a.clockwise(c)
Introspective: in a language like Python you might return to the procedural form, but check at runtime about the exact type of argumernts a and b, and do sensible things if they're not as expected.
Re: Useful or abuseful?
In my experience the preprocessor in C and C++ is inadequate for cases where one's program code is best generated by another program. Use a stand-alone macro-processor, or write your own code-generator in (say) Python. Then just build it into your makefile. But do try to make sure that it emits debug-able code!
Re: Scientific and Engineering Computing
A few people code in Python - and quite a lot of these people use it for intensive tasks, which makes me quite worried for the laptops they then try and run it on
If they know what they are doing, they are using NumPy and SciPy and suchlike. That means that you do the high-level stuff in a high-level language (Python), but delegate the number-crunching (inner loops, BLAS) to library code written in whatever low-level language the library author chose to use. Actually, there are multiple choices: the same library interfaces compiled with different optimisations (say for Athlon, or Intel Xeon, or rewritten using CUDA for offloading onto an NVidia GPGPU).
It's a VERY productive way to go.
The principle was much the same back in the 1970s when a sensible scientist called a NAG library routine whenevr he could. Do as litle coding as possible in (back then) FORTRAN, leave the details of how to get the most out of the hardware and how to tame the numerical methods to the experts. All that's really happened is that a much more powerful and expressive language (Python) has displaced FORTRAN, C and C++ as far as stringing together calls to library code is concerned.
Incidentally the overhead of doing inner loops and all in Python is a factor of ten at worst. In cases where the prospect of getting ten times as much computing done isn't attractive because human thought, not CPU-hours, is the rate-determining factor, then why care about efficiency?
Troll? OK, probably not.
A 33-bit processor would be very silly. It would mean that it had an Integer operations unit that could do 32-bit integer arithmetic and 33-bit pointer arithmetic. But fetching packed 5-byte fields would slow down the memory system compared to fetching aligned 8-byte fields. So the 33-bit integer operations would need to load and store 64-bit fields and fill the top 31 bits with zeros.
And then next year when the manufacturer wants to make a 16Gb version? All your 33-bit code would have to be recompiled and revalidated for 34-bit operation!
The only reason for 32-bit CPUs was that the cost of four extra RAM bytes per pointer was significant back in the days when we were migrating away from 16-bit CPUs. Today, the cost is not significant and 64 bits is the natural size for a pointer, that will be big enough for a LOOOONG time to come. (Hint: calculate the number of protons in the whole Earth. We won't need 128-bit addressing until we're well on the way to converting the whole solar system into computronium. )
Some people confuse the number of bits operated on by the integer processor with the size of a physical RAM address. That can be any number of bits. Virtual to physical mapping goes from a 64-bit number to an N-bit number. Most of the possible 64-bit virtual addresses cause access violations. That's also good: it makes it more likely that randomly corrupted or miscalculated pointers in a program get noticed and debugged! Cue remisiscences about the uses of 0xDEADBEEF or 0xDEADBABE or more boringly, IEEE Floating-point NaNs with the low-order bits set to the address they are stored in.
Re: "Anything X86 failed to do in the first case it can do in later cases"
Intel still has the advantage of better process technologies than anyone else.
The interesting thing to watch will be whether Intel's process tech is sufficient to overcome all the historical baggage that an x86_64 chip has to carry around. The "green dream" would be ARM CPUs fabbed by Intel. It may come to that one day.
Also there's a large, though gradually diminishing, pool of software that isn't yet available to run on anything except the x86 architecture. That may be a lot more significant to business customers than it is to consumers.
plug into the BGA1286 socket - boggle
Someone doesn't know what BGA is.
It stands for Ball Grid Array. The balls in qustion are small solder spheres, by means of which the CPU is permanently melted onto its motherboard as per current Atom designs. In other words, the CPU in a Centeron server is not upgradeable (other than by replacing the entire motherboard). Since almost everything apart from the connectors and the RAM is on the chip, that's probably no great loss.
Nevertheless, a 6 watt chip that plugs into any i3 socket ,which doesn't need active cooling, would be welcomed by myself. (Yes, I do know if you spend £100+ on a box, you can find exotic cases that are in effect hundred-watt heatsinks, containing multiple heat-pipes to remove heat from a full-power desktop CPU)
Re: the customer is always wrong
Well, I want one of these for my always-on home server. (Which at present is an older Atom system that uses more watts for less performance).
With completely passive cooling and a solid-state disk drive, so zero noise. (current is passive cooled but not SSD)
And I get ECC RAM, so no data-corruption caused by faulty RAM
And I get to run VMware, so on the rare occasions I want Windows, I can have it without rebooting.
Unfortunately Intel's web-site doesn't yet reveal any S12x0 motherboard that I can buy, lt alone whether there's a mini-ITX one.
Funny - I thought malaria pre-dated artificial lighting. I always thought that those pesky mozzies fount their way around by sense of smell. The moment you turn the light on, that annoying meeeeeeeee noise stops, and you can't find the bloody insect to swat. Maybe that's only Italian hotel mozzies, though. Or maybe you are confusing mozzies with moths?
That aside, wouldn't people be happier with more usable hours in their day? Eight hours sleep is plenty, but the sun is down for twelve-ish hours (near the equator). Which is why they use fires or candles for light, which is wasteful, hazardous, and smoke inhalation is a long-term killer.
I imagine it's a simplicity / cost thing. A spring and associated winding mechanism costs more? Likewise, I imagine, a dynamo-charged battery as in any number of wind-up torches in a shop near you.
For long-term reliability, I would have thought a solar cell and battery better (ie directly stored sunlight) No moving parts to fail. But I guess poor folks can't afford the extra capital outlay even if it did come with a 25-year guarantee.
Re: Install Linux and let 'em come
Microsoft resorted to various dubious if not outright corrupt practices, in order to get its own Office file formats accepted as an international standard (OpenXML) alongside the Openoffice ones. Otherwise, Openoffice users would have been able to kick back by saying that our odt files are ISO standard, and your [xls, doc, ppt]x ones are not!
Re: What a waste of time
In practise almost no one else is going to take the lid off the SAMBA source code
A very large number of things one can do with Samba don't involve taking the lid off. They just involve reading the documentation and attaching code to hooks that Samba provides, and Windows server does not. Start with the pre- and post-exec hooks on any Samba share.
It's also the nature of open source that if there is a need to attach code to some new action taken by Samba, then someone somwhere will open the hood far enough to create a hook. Also that if there's no good reason to oppose the creation of that hook (security?) then that mod will migrate into the main Samba tree quite soon thereafter.
It's the difference between a product that wants to be used and useful, and a product that wants to force you to buy more secret closed sauce (or snake-oil) at every opportunity.
Re: C'mon own up
I think the right question is "Who the fuck still wants to own and run the latest Linux kernel on a 386". For which I cannot offer any good answer.
The obvious answer to the question as posed, is anyone who has a large investment in a piece of hardware that's still useful and which would be very expensive to replace, which is controlled by an embedded 386 PC that runs linux. I don't have to look after any lab equipment that runs Linux. I do know of two pieces of lab equipment that still run Windows 3.1, and a couple more locked to Windows NT4. When I can no longer fix the computer, the bill for a modern replacement will be five, maybe six, figures.
Mini-Ethernet? Hadn't heard of it before, but looking at the pictures it's clear that it would have been very hard to fit in a standard RJ45 connector.
Anyone know if it's a standard (like mini-USB)? If so the cables will become widely available at low-ish prices and interchangeable between manufacturers. Maybe we'll even start seeing mini-Ethernet connectors on tablets, where a full RJ45 would be quite impossible.
A sheet of paper printed at 300dpi is about 2400 pixels across and 3300 deep. If you degrade your printing to 150dpi (1200 x 1650) you most assuredly notice the jaggies on slanting linse and glyphs!
300dpi is old hat. Many of today's laser printers are 1200dpi, although I'm not convinced I can tell the difference between a 1200dpi laser and a 600dpi laser. 600dpi looks crisper than 300dpi although that diffrence is more subjective than objective.
Anyway, this shows there is a limit to the number of pixels that could benefit a laptop user, but we haven't yet got close to it with screens and monitors.
Re: @AC 13:00
Carbon-capture is extremely feasible. The plant you need to accomplish it is called, er, a plant. Every year the atmospheric CO2 concentration cycles by about 15ppm (average concentration is now 380ppm). This is because the mass of deciduous vegetation in the Northern hemisphere is greater than that in the Southern hemisphere. This tells you that if we could prevent all decay of fallen leaves, we would probably remove all CO2 from the atmosphere in less than 20 years! (Not, of course, a good idea to go this far).
So: genetically engineer or breed a common crop plant to grow more root than it needs, and to surround parts of its roots with something that will protect the root from decay for a long time after the plant dies (ie, is harvested). Interestingly, Wheat naturally does this to some extent. Its roots excrete tiny silica nodules, and the root inside the nodule does not decay for millennia. Some varieties of wheat do it much more than others. To start with, grow only those varieties. Selective breeding may well further increase the effect 10, even 100-fold. (Think of how we've shrunk a wolf into a Yorkshire terrier). GM might do a lot better still.
Or we could coppice lots of forest, and instead of burning the biomass for power, process it into a form of cellulose that's highly resistant to microbial attack and dump it into a deep ocean trench (from where nature will subduct it into the Earth's core). Such a form (nanocrystalline cellulose) does exist, and in fact has a lot of promise as a replacement for oil-based plastics.
Surely that all depends on how likely it is to be dropped?
If it's a piece of test equipment that is used on building sites, the ability to survive being dropped onto hard concrete or into a muddy puddle verges on essential. For a camera to be used by a war reporter, even more so. If it's a 24inch office monitor or printer, it doesn't matter at all. OTOH surviving a cup of coffee being spilled onto it, or surviving a sheet of jammed paper being wrenched out backwards by an 800lb gorilla called "sir", are useful attributes for a printer. I've watched speechless as that sheet of paper come out along with a handful of small broken plastic pieces.
My list of unexpectedly tough kit has Fluke DVMs and IBM ThinkPads near the top, and Sony VAIOs near the bottom. An HP LasetJet 4 is tough and longlasting, but does not survive a flight of concrete stairs at the hands of a "professional" removals company.
And the most memorable "failed" drop test of all was an 80Mb (yes MB) disk drive the size of a washing machine back in the 1980s. The engineer unpacked it, took one look at it, and told us he needed to call the insurers. I asked what was wrong - it looked fine. "Well", he said, squinting, "it's an inch wider at the top than at the bottom". Indeed, it was. "And it rattles when you wobble it. And [grin]... it's got a hole the shape of a fork lift truck prong in the side, right through all the controller boards".
Re: I thought...
You don't need WMD if you've colonised the moon. You just need a mass-driver and a pile of big rocks. The first space war may be fought with (updated) stone-age technology and stone-age military strategy, and will inevitably be won by the moon because it's the really high ground.
Heinlein "The Moon is a Harsh Mistress" set this scenario in 2076. 64 years to go. Still just about possible.
Re: @ Michael Luke
Isn't that HAD lots of oil? There's not a lot left, and the Scots may take those dregs with them when they vote for independance ... and shortly afterwards, get invaded by the USA?
Back in the real world, it's actually the USA that again has lots of oil, thanks to fraccing technology and abundant supplies of oil shale.
Is that question rhetorical?
While wrestling with this afternoon's wireless WOMBAT (above), I also took the opportunity to see whether Windows 8 was usable without touching the screen and without loading a Start-menu replacement.
The conclusion I came to was no. "8" out of the box is completely unusable if all you have is a keyboard and a mouse. And a 24 inch touch screen at the far side of a desk would be an RSI-inducing ergonomic nightmare, even if anyone is stupid enough to make one.
PS For some reason I keep getting Windows * when I thought I'd typed 8. Maybe the Register-approved designation should be "splat", in a geek version of Cockney? splat = asterisk = shift-8 with a nod to Intercal, the only language to make BASIC look cool.
Re: fix Windows 8 by making the Metro interface optional
ALL my headaches?
I spent an hour today trying, and failing, to connect a Windows 8 laptop to our "corporate" secured wireless network. Many of the control panel screens are exactly the same under the hood as Windows 7, but where has "Manage Wireless Networks" gone in "Network and sharing centre" when you need it? Indeed, why have they changed control panel yet again to hide or remove previously existing functionality ... for the second or third time since XP?
The problem might be a typing mistake, or it might be something really tricky, but I can't find out how to get it to display what I'd typed in the previous few screens, let alone what defaults it has assumed. I also can't find out how to delete a wireless configuration so that I can try again from scratch. It won't let me try the same again ... says I already have a network called xxxxxxx and dumps me into a black connect-to-xxxxxxxx *-style panel on the RHS that has no options (like, say, right-click properties), and which I already know will fail to connect, for the Nth time. I'll doubtless be wrestling with this WOMBAT again.
Still hating 8 every time it crosses my desk.
Re: It's simple
You think they relate to the average enterprise environment much better?
If they had half a clue, they'd have replaced Windows XP by something which an average employee would think was still Windows XP. Same UI, all the same apps still working, all the same old protocols still working. Even though there would be a shiny new kernel under the hood, lots of shiny new protocols and maybe even a shiny new desktop UI available for use just as soon or as late as the customer decided that they wanted the new features
Doing it this way would even have made more money for them. we'd have paid for the upgrade licenses, rather than hanging on to XP until the bitter end. I'd have been overjoyed if upgrading to my fictional "Windows XP7" was something that I could do a few desktops at a time, overnight, with the users mostly not even noticing that they'd been upgraded.
But no, Microsoft thinks if it says tear it all up and start again (Vista), and again(7), and again(8), everyone will be overjoyed to do just that. F**k them.
Re: Too little, no credibility, too expensive
There's something hilarious about a company which ever thought of BASIC as a systems implementation language. Even though it did make very many M$ for its founders.
thick as a brontosaurus omlette.
Re: Wrong tense.
where the band is playing...but the Titanic sinking...and HTC and Nokia were first class ticket holders
So where is Nokia's lifeboat? HTC first class, Nokia at best second class in that analogy.
Completely agree with the original poster, by the way.
It's also probable that the more heads you try to stack on one actuator, the greater the problems you have taming all the vibrational modes of the assembly.
Smart way to go, especially in the long run
The nanostore design appears to place energy efficiency above data retrieval rates
Also massively distributed processing.
I can think of something else that works this way, that's been honed by hundreds of million years of evolution. I'm sure you can too ;-)
Yes, Wintermute was good.
If you're into books, I've always thought the best SF computer (as opposed to fully-fledged superhuman AI) was in Greg Bear's "Queen of Angels" and "Slant". JILL is female, not at all malevolent, and (in the first book) convincingly not-quite-self-aware.
The first book also contains a very scary monster. To say more would be a spoiler.
... the Cylons?
At least that one had an interesting premise. (Was it chosen to minimize the effects budget needed? )
Re: Mistake Not...
Course you could film a culture novel. "Inversions" wouldn't even cost you much in special effects. "The Player of Games" would cost a lot more, but surely no harder than "Lord of the Rings"?
Making "Excession" interesting on screen would be a challenge.
Re: Dark Star?
Of course it's a computer. Just an embedded one. One capable of talking philosophy and suffering existential doubt. Superb.
Kipling knew better
We never pay any-one Dane-geld, // No matter how trifling the cost; // For the end of that game is oppression and shame, // And the nation that pays it is lost!
For nation read company, for Dane read troll (didn't trolls come from Denmark anyway? )
the whole poem is worth reading http://www.poetryloverspage.com/poets/kipling/dane_geld.html
Re: No! Bad! BAD REG!
Not very long at all, to swim half-way across. After that all bets are off. Just maybe, ...
There was a young lady named Bright // Who could travel much faster than light. // She took off one day, // In a relative way, // And returned on the previous night.
Re: Result of galaxy collision?
Maybe something like that. You have to kill a lot of angular momentum so that most of the galaxies' matter can fall into the centre. Maybe two contra-rotating galaxies with nearly equal but opposite angular momentum approaching each other very slowly (relatively speaking) down a common axis of rotation, leading to a merged one with almost no angular momentum?
I imagine that the astronomers are busy running lots of simulations, trying to work out how it happened, or whether it's physically impossible (under current accepted physics) rather than merely unlikely. The biggest anything is almost always unlikely. and there are a LOT of observable galaxies.
Re: Dark Matter
Well, it's hard to calculate the mass-density of the observable universe exactly, but it's in a very narrow band of all the possibilities. Slightly higher, and the universe would have collapsed back into a singularity (or at least a very small very hot entity) so long ago, that planets and life could never have formed. Slightly lower, and the universe would have expanded so far and so fast that there would be no stars, galaxies, planets or life, just a very thin soup of particles very close to absolute zero.
Hence to the weak antrhopic principle (for atheists) or the hand of $DEITY (for the religious).
Black holes betray their presence by their gravitational influence on the things around them. It's doubtless the odd nature of this galaxy that lets us deduce that the black hole at its centre is a monster, just as "ordinary" galaxies let us deduce the presence of an "ordinary" galactic-centre-sized black hole. So unless monster black holes can be lurking all alone in intergalactic voids (how?), they can't be the dark matter we are looking for. And anyway, we need a dark matter halo to make gravitationally bound galaxies work at all, and then there's the Bullet galaxy where two galaxies have collided head-on and one can observe the separation of the formerly-associated dark matter.
Biggest != Typical
Shouldn't one always expect the biggest of anything to be an outlier, an anomaly, a bit of a freak? Unless it's difficult to concoct any scenario leading to the formation of this monster, one should surely assume that the observable universe is large enough for even very unlikely things to have happened somewhere.
And of course, the biggest is also the one shouting loudest for our attention. (Well, apart from Gamma-ray bursts, whatever they may be! )
After the Star-TAC ...
After they built the Star-TAC, the only way was down.
I'm not saying that it was the best ever Motorola phone, nor that phones haven't advenced very much further. Just that when you realize something out of "Star Trek", that the TV series thought couldn't be attained for a few centuries yet, you've reached the top.
My mother finds most mobiles too small and fiddly for her ageing hands and eyes. She'd love a Star-TAC (same size, much the same user interface, modern cellular tech inside).
Re: You keep using that word. I do not think it means what you think it means.
She did take someone else's (intellectual) property. If it was done with provable intent to evade paying the license fee, then it was theft. Composers and performers, and perhaps even the horrible multinational companies to whom they sell their copyrights, do have a right to earn a living (and if composers couldn't sell their copyrights, how would they then earn a living? )
Of course it wasn't theft on other grounds. Firstly, a 9-year-old can't reasonably be expected to understand such fine points of the law. What's the age of criminal responsibility in Finland? It's 10 in the UK. Secondly, how can someone know that what is delivered when one clicks a link is delivery of stolen goods? That's as daft as saying you're a thief if you un-knowingly buy a packet of crisps from a shop run by a man who nicked a big box of them from Tesco. It's the person who knowingly posted the link to stolen intellectual property that is the thief.
Rechargeables, for Gaia's sake!
Not a lot of rechargeables. One spare set, or maybe a few shared sets and a charger kept by the person who volunteers to swap your discharged ones for recharged ones.
Rechargeable NiMH has come a long way. The last excuse for not using them was that they self-discharged in about six weeks. The latest ones don't. (The ones that come pre-charged in the packet).
The government ought to raise the tax on non-rechargeables so that they cost more than the rechargeable ones, and start a public-awareness campaign. I guess a few dim light bulbs will still throw them away after one use, but one has to start somewhere.
Re: Halon Rocket Fuel
I've heard a similar story. Except it was a high-pressure air cylinder that someone had unstrapped from the wall and propped against another. It toppled, struck its neck on the bottom rung of the decorator's step-ladder, fractured, and went through three walls ending up embedded six feet into a hillside. No-one was killed. The decorator's deafness was temporary.
Or so I was told, over a beer.
(The REALLY scary stories involve overheated acetylene cylinders, which make unexploded WW2 bombs look friendly.)
Re: This brings me happy memories
Halon is NOT an oxygen suppressant. That's CO2 flood.
Halon removes heat, not oxygen, in a rather clever way. When it is heated to its decomposition point, that is an endothermic chemical reaction. It absorbs heat, thereby cooling the flame. Further, the Bromine and other halogenated fragments that are released bond to the free radicals in the flame, so the flame is not only cooled but rendered incapable of catalyzing decomposition of its flammable substrate to generate more fuel for itself to feed on. It goes out and stays out.
It's exactly the same property that makes it so dangerous in the upper atmosphere, where UV decomposes it and where the fragments then catalyze the destruction of Ozone. Which is why it's been banned except in the most critical of safety-critical fire-suppression roles. Computers gave to take their chances with sprinklers, or be put in a true lights-out room with a CO2-flood system that kills both fires and people.
Re: This brings me happy memories
Let's prevent deaths from smoke inhalation by killing anybody who might be in the room wanting to breathe.
Only in the parallel BOFH universe. Or you are confusing Halon with CO2 flood.
In the real world Halon is almost inert and is not used in great enough concentrations to asphyxiate. If you were in the computer room when it dumped you would be off work with a monster headache the rest of the day and the next. It's not clear whether that's because of the huge noise it makes (only just short of eardrum-breaking), because of the flying ceiling tiles that the release usually causes, or because Halons have another use. The Anaesthetic gas that hospitals use is a halon.
Maybe someone once got fully anaesthatized, and that started the urban legend about it killing fires and people and leaving equipment unscathed?
Re: Pretty sure its not malice
Hmmm. From a black-helicopterist perspective, that's the cost of employing someone incompetent on purpose, so you can't get hit with a monopolies lawsuit and made to fund a not insignificant part of the EU's deficit.
In passing, you don't need a UEFI BIOS to support disks >2Gb with Linux, provided you are happy with the plural. Once a linux kernel is up and running, it'll handle a disk with a GPT without any use of the system BIOS.
So boot off an SSD for a faster system. Or load your kernel from a USB memory stick if you want it cheap. Or off a CD (try root-kitting that!). Or even put that old 80Gb drive back to use.
Re: Never ascribe to malice that which can adequately be explained by incompetence
In the long view, malice is simply a subcategory of incompetence anyway.
Only if there's an afterlife. Otherwise if you can make off with a large amount of someone else's money or other valuables, and get away with it until you draw your last breath, then in the long view malice has paid handsomely.
Re: File this one under...
You might come to think "right reasons" if you consider that she doesn't want to be forced to wear a tag because it's against her principles, and you don't want to be forced to wear a tag because ...
The opposition being the people who say fuck your principles, do what we tell you or we'll hit you with something.
Which is of course why "their" next step will be to implant the chip in our foreheads at birth once the infrastructure is omnipresent. Are we quite certain that those religious people are complete fruitcakes?
Re: I predict...
If you read the article, you'll see that you need a working RFID tag at that school, in order to be able to use the toilets. So you'll most certainly have something to hide by the end of the day.
- Top Gear Tigers and Bingo Boilers: Farewell then, Phones4U
- Analysis iPhone 6: The final straw for Android makers eaten alive by the data parasite?
- Stephen Pie iPhone 6: Most exquisite MOBILE? No. It is the Most Exquisite THING. EVER
- First Crack Bloke buys iPHONE 6 and DROPS IT to SMASH on PURPOSE
- Early result from Scots indyref vote? NAW, Jimmy - it's a SCAM