You didn't read my post, did you? You can turn it off globally, but it's really hard to then turn it on for a subset of applications. You have to individually disable each one's access (and they all default to 'on', so you have to remember to do it again after installing each new app). If I turn on mobile data somewhere expensive to look something up urgently (or, for example, to get an updated boarding pass for a flight) then suddenly a dozen applications will say 'whee, Internet! Let's download a load of updates!'

If you're doing a million items, then the difference between O(N) and O(N^2) is a factor of a million. If each operation takes one cycle to complete, then on a 2GHz CPU you're going to take 500 microseconds. More plausibly, if each iteration takes 10 cycles, then it will take 5ms. The O(n^2) version, assuming the same ten-cycles per operation (which is pretty small - even a bubblesort on integers in an array will be hard pressed to be that quick), will take one hour and 23 minutes.

If you really think that the difference between 5ms and almost an hour and a half is irrelevant, then I really hope that I never use any code that you write.

De Morgen's laws are widely known and trivial to automate. Any vaguely modern compiler knows about them and will do the transform for you. Not only will it do it for you, it will do it for you everywhere and base on knowledge of the target architecture.

That said, it won't rearrange things that might have side effects. In C, for example, you have short-circuit evaluation, so if you have something cheap on the left of an or and something expensive on the right, then it will be faster unless the compiler can determine that the expensive thing has no side effects. If you have a negation of a long string of ands, the arguments to each of which is expensive to compute, then turning it into a string of negated ors is faster, because the compiler can stop computing once it's found one that's failed.

Exactly what I came here to post. We had the demonstration of what happens when you immerse something in liquid nitrogen vs what happens when you pour it over the top. Even if you didn't get to play with liquid nitrogen in school, there are lots of videos of this.

Some Fortran 66 code that was certified as accurately modelling explosions before the ban, which no one is allowed to modify, run on ever-more-expensive supercomputers.

Or, you put it another way, the most expensive wishful thinking on the planet.

When people say 'first strike' in this context, they mean 'nuclear first strike', as in 'launch enough nuclear missiles to take out your enemy's ability to fire back'. The reason for nuclear submarines is to largely eliminate this possibility: even if you completely destroy every military installation in the USA, there is going to be at least one submarine hidden somewhere that will be able to flatten a few of your cities.

MAD only works as a deterrent if there is a very small chance of getting away with a first strike. If you can shoot down incoming ballistic missiles, then you might be tempted to launch first and just shoot down the retaliatory strike. If you can fire missiles that are fast enough that the enemy doesn't have time to order a retaliatory strike, then you might be willing to live with a couple of submarines shooting at you, especially if you have a good idea of where they are and can have aircraft ready to launch interceptors flying above them.

Aircraft carriers completely suck for launching nuclear missiles (and the USA has not confirmed that they even bother putting them on board), because they're a big obvious target. If, for example, the USA put a nuclear-armed aircraft carrier near Russia, then you can bet that the Russian second-strike capability would be on alert and ready to launch unless they got regular confirmation that the US carrier hadn't launched. Aircraft carriers also suck for second-strike, because they're too big to easily dodge a nuclear strike and so will be on the list for first-strike targets.

They're good for a conventional (non-nuclear) first strike, because they give you a staging post that you can put right next to someone else's country, but that's less of a problem for global stability. A non-nuclear first strike commits you to an expensive war. Aircraft carriers aren't also specifically first-strike weapons. They have support roles and are even occasionally used for disaster relief (a big portable nuclear reactor turns out to be quite handy sometimes).

Five hundred hostiles is well within the targeting capacity of a single Apache, let alone a warship. The reason that the US Navy has been investing heavily in laser weapons recently is that there's a gap between being able to target them all and being able to shoot them all.

There is, but it's to coarse grained. For example, I'd be happy for an IM application to use mobile data, because it's likely to be very low traffic. I'd like my web browser to use mobile data sometimes: when I'm away from WiFi and need to look something up urgently. I want everything else to be restricted to WiFi. I want these settings to vary slightly between when I'm at home and when I'm roaming, as data charges can vary by a couple of orders of magnitude.

Android actually does provide an interface for doing this, but everything defaults to being able to be used all of the time. Within some applications (e.g. web browser) I want something like the old 'show images' button from the MODEM days, so that images, videos, and anything else large will not be downloaded unless I opt in on a specific page.

Wikipedia has a list of countries ranked by GDP. Let's look at where the BRICS countries are on that list:

• Brazil: 7
• Russia:8
• India: 10/11
• China: 2
• South Africa: 29

For comparison, the USA is #1, Germany, France and the UK are 6-8. Now, if you're the worlds second-largest economy, would you prefer to have the worlds eighth-largest economy as a trading partner, or the world first, third, fourth, fifth and sixth? Now, if rational choices aren't enough, keep in mind that (in the scenario under discussion), the current President of #8 is someone who fondly recalls the days when you were a junior partner in an alliance and has demonstrated a willingness to use nuclear weapons.

The BBC news article about the hack had a quote from one of the celebrities saying that the pictures had already been deleted before they were stolen. That is the problem with these services: they don't securely (or, at all) delete things. Google's deletion mechanism, for example, relies on simply not actively copying the files to newer disks so that when the old disks eventually die the files are gone. I wouldn't be surprised if Apple's works in a similar way. Even if you decide you don't trust Apple/Google/Facebook today, you've got a long wait before all of the files that you've uploaded to them are gone.

Step one is to have the big high-profile stories in the press about the problems. Step two is to have the big high-profile stories in the press about the alternatives. The important thing now is for anyone who is contacted by the press as an expert to ask about the iCloud hack to make it very clear that this isn't an Apple-specific problem, it's a problem inherent in the entire design of centralised services and to list alternatives.

It was on the BBC news this morning, which probably counts as more reliable than 4chan. Most interesting was the claim by one of the women involved that the photos had been deleted. If this is true, then it would be a great example of the fact that just because something is 'deleted' in the cloud doesn't mean that malicious people can't get at it in the future...

If I'm going to report errors in a map, I'd rather do so with a map that releases its data under a license that allows reuse. Since such a map already exists and doesn't have the errors in Google Maps, I don't see much incentive. Google can pull the data from there if they want. This is actually one case where Microsoft has been a bit nicer: they allowed OSM to trace their satellite images to improve maps. Google Maps, in contrast, is very protective over their data.

Not sure what post you think you're replying to, but the quoted line didn't appear in my post...

I don't know about rural Japan, but I found the OSM data far better when I visited Tokyo a few months ago. Google didn't know building names and placed a load of things that we were trying to visit a few blocks away from where they actually were. This was very frustrating as the web site that we were using to find vegetarian restaurants used Google maps - we spent half an hour one lunchtime walking in the wrong direction, because we'd come to a junction and, according to the Google map needed to turn left and would then see our destination on the right. It turned out, when we eventually found it, that we should have turned right.