Didn't know that; that's somewhat good news. Nonetheless, I'd like to stretch it out as much as possible (I can trace some tiny part of my ancestry back to William the Conqueror's apple-keeper -- it's good to take the long view, right?) The claims made for thorium reactors are interesting, to say the least, and we've got a lot of it.
You are aware, that without breeder reactors, we're not terribly far from "peak uranium", right? Something like a hundred years at current consumption, which is much lower than the replace-coal consumption rate.
You are making claims that can be supported (or not) with numbers, it would be helpful if you provided some.
Y2K Census data if you take the data for metro areas (this is conservative) sort by density, then compute the cumulative population, you find that:
40 million people live in metro areas with density exceeding 2000 per square mile
the next 20 million, 1395 to 2000 per square mile (60M)
the next 20 million, 1200 to 1395 per square mile (80M)
the next 40 million, 1032 to 1200 per square mile (120M)
the next 40 million, 777 to 1032 per square mile (160M)
Out of the Y2K total of 281 million people, about 20% (60 million) live in metro areas more dense than 2000 people per square mile. Over half live in places denser than 777/square mile, which may not be dense enough. To make the case that we're not like Europe, we'd need similar numbers, but it seems safe to say that an awful lot of people live in decently dense places (note that Atlanta metro (692/mi^2) did not make the top half -- they are at the 176M cumulative mark)
Because these are metro areas, there is still room for tighter and looser clustering -- so for example, there are surely parts of the SF/Oakland Metro area that are too spread out for commuting (there is the small matter of the Bay Bridge), but there are also tight clusters within less-dense metro areas -- for example, the Boston Metro area is at the 143 million mark (last 40 million above) at 926 ppl per square mile, but I start my commute in one town of 4900/mi^2, cross a town of 7900/mi^2, cross a town of 1800/mi^2, and end in a town of 2100/mi^2. This suggests that metro areas may be too granular, but it also suggests that what matters more than density, is distance to work; I would not be surprised to discover that there's a higher percentage of people working-from-home in some of interesting, very-low-density places.
The median commute distance in the US (as near as I can tell, it is hard to determine exactly) is somewhere around 11 miles. This may be a more important number than mere density, because some of the big metro areas have expensive housing and long-distance commutes (SF/Oakland, in particular, as well as NY, and Boston, for that matter). But, a 10-mile commute is doable by bike -- in particular, doable by an old fat guy on a cargo bike. I knew this when I started, because I used to ride 10-mile time trials as a kid and they were no big deal.
I disagree, very much. I know one climate scientist, and I know quite a few people who do that sort of modeling (it's all variations on finite elements, with various hard parts stirred in). Some of them are doing stuff that is completely far-out, meaning, trying to model the process by which a star goes nova. The obvious question is figuring out how the model diverges from reality, how to test that, and how to fix it. That's pretty much their focus. As far as agendas go, I suspect it is the other way around -- if the models keep telling you that we have a serious problem, eventually you might start telling people that it looks like we have a serious problem.
The coal industry, in contrast, has a duty to their shareholders to promote the further profitability of the coal industry by whatever legal means there are, and they are not required by law to tell the truth except in certain special circumstances (SEC reports, testifying under oath, that sort of thing).
Despite substantial uncertainties, especially for the period prior to 1600 when data are scarce, the warmest period prior to the 20th century very likely occurred between 950 and 1100, but temperatures were probably between 0.1C and 0.2C below the 1961 to 1990 mean and significantly below the level shown by instrumental data after 1980. The heterogeneous nature of climate during the 'Medieval Warm Period' is illustrated by the wide spread of values exhibited by the individual records.[12]
Here's some reasonable data somewhat supporting your solar intensity hypothesis. The problems are that (1) now that we can observe intensity directly, we haven't observed large enough changes (2) your assertion about the relative warmth of the MWP seems to be not quite correctn and (3) where's the huge pile of sunspots?
I found no problems in anything that you referenced, because you referenced nothing. If you want to make a case, please support it. The "standard sources" (Wikipedia, top hits in Google) don't.
1) it depends upon what the meaning of is, is. (yes, I did use present tense. I should have been vaguer. You're being pedantic, and you know it.)
2) The symptoms-addressing is more of a future problem than a present problem, so it has the same 20-year horizon. The one thing that might make sense to address now/ASAP, is warming in the arctic. Intuition says that's going to have nasty feedback effects in the future. However, if you decide that you're addressing symptoms, intuition is hardly a reliable guide, and it seems like you are buying heavily into the very models that we're not dead sure of -- what action addresses what symptoms, what is the magnitude of the action, what are the predicted side-effects? We might end up, saying balancing ozone destruction against warming, or acid rain.
3) If we won't have a fossil fuel replacement in 20 years, then we should start developing one in 1980. Failing that, now. I would, in fact, like to see the market work on this one, and the best way I know of to get the market moving is to convert the hypothesized external cost of carbon emissions, integrated over all modeled futures, into a tax, and phase it in on a schedule that we hope tracks the rate of non-GHG energy innovation, or maybe pushes it at little bit. I'd rather not have the government choosing favorites, except perhaps proven ones (things show to work in Europe where they already have half our footprint), and ones to help in the 3rd world.
It's the integration-over-all-outcomes parts that's the real problem. Just as certain banks and hedge funds recently did, I very much get the impression that lots of people are only considering the most-likely outcomes. For the US, most-likely is not-that-bad, and for people (like me) who live in the Northeast, or many Canadians, well, it might even be positive (shorter winter, summers no hotter than what I grew up with in the South, ok). But the tail of outcomes contains some extremely high-cost outcomes of distinctly non-zero probability, at least using the models that we have now. Their cost-weighted measure is enormous -- if we trust the models. And do we trust the models, more than, say, coal-industry spokesmen?
I am not so sure of this (and note that you are making an essentially economic prediction about the future, and we're not too good at those, either).
If we're serious about GW, we start with an increasing CO2 tax, beginning at somewhere between $10 and $50 per ton of CO2 (think, burning 100 gallons of gasoline). You'll notice the price differential, but we've had worse fluctuations in recent years. And it goes up, and everyone knows it goes up. Europe is an existence proof for how we can live pretty well with half the CO2 footprint, and high gas prices.
At a certain CO2 tax, alternatives become economically interesting. Don't fart around with random subsidies and targeted stuff like that, just make it clear what will happen, and let the market go at it. DO see about a national effort to upgrade the power grid.
But, such a tax, certainly means the end of the coal industry, probably in my lifetime. They won't be able to compete, unless they can make the whole sequestration thing work. And they might.
I have enough trouble following my own field; I know at least one climate scientist personally, and he's well and truly convinced. But, every time someone has put forth a contrary theory, if/when I take the trouble to look into it, it falls apart. So if there are better contrary theories, by all means advertise them (links, perhaps?) The massively funded PR campaign is surely working against good science here, since I am certain that they will indiscriminately fund scientific-sounding cranks.
There is this other problem, which is that in any naive model, increased CO2 absolutely increases temperature, because it really is a greenhouse gas (transparent to many wavelengths, blocks various IR bands). So a good theory would not only explain observed warming in ways that did not depend on CO2, it would also demonstrate (or a companion theory would demonstrate) why CO2 does not produce warming in the world that we live in. (And obviously, we know we are not living in the naive model.)
This is somewhat different. The defenders of the Static Universe did not have Sagans and Sagans of dollars depending on the acceptance of the theory. If we took global warming as a drop-dead-serious problem, it would be the end of the coal industry, and business would be very different for the oil industry (plastics, we still need plastics). The auto industry not be on life support; it would be dead and buried.
There is, in addition, the problem that we already have nice solid evidence of an earlier spring (the yearly spring dip in the Keeling Curve is beginning earlier), and we have a mechanism dead to rights for why increased CO2 should make the earth warmer. The science on this is not weak; our main problem is that we are trying to get data out of a noisy system, and there's no control. In contrast, the it's-not-happening crowd does not have a good explanation for why it should not be happening, nor do they have good data showing that it is not happening (noisy data has the annoying property that it proves nothing for nobody, neither presence or absence). They do sometimes say things that sound scientific, but those typically get holes punched in them with a quick visit to Wikipedia. So, not really.
As far as "trying to shut up the other side", well, yeah, it gets f*cking frustrating, if you're not just arguing with other academics, but instead have to deal with a well-funded FUD and PR campaign, that can even afford to buy senators. This is not an ordinary "scientific debate".
Catastrophic cancellation -- suppose you have C1 = a + bi, C2 = x + yi. Multiplying them yields (ax - by) + (ay + bx)i. Done "naively", those embedded subtractions/additions can lead to excess cancellation. The "easy" way to deal with this is to do the intermediate multiplications (ax, by, ay, bx) into higher (doubled) precision, do the add/sub in the higher precision, and then round down to get your answer. Works pretty well for single (because double is always available), not so well in double (because quad is sometimes architected, but not supported except in emulation). There are probably some tricks for doing this well with IBM Power's fused multiply-add.
Range reduction is substantially more subtle, and it requires that you understand a particular point of view. That POV is that each machine floating point number is exactly what it is -- the representation of pi (the 64-bit mantissa approximation that you get in 80-bit Intel FP) is expressly, NOT PI, it is a different number, very close to PI. So, consider sin(PI+x) for a moment, for very small x. That should be very nearly equal to -x. Now, suppose you take a 64-bit mantissa approximation of PI, call that "pie". I happen to know that it is slightly larger than PI, hence the "PI+x" formulation (bits 65-68 = hex C) (I may be making sign errors here). Suppose you want to computer sin(something), where something happens to be pie. The first thing you notice is that it is (a) larger than PI and (b) also larger than the 68-bit approximation of PI. So, either way, you need to do range reduction, subtracting either a sufficiently large approximation of PI, or subtracting a 68-bit approximation of PI. If you subtracted true PI, what you get is 64 (63?) zeroes in the mantissa, followed by 1 at the 64th position (because pie is rounded up) minus all the following digits of true PI. If, on the other hand, you subtract the 68-bit approximation of PI, you get 64/63 zeroes followed by binary 0100 (16-12), and all the rest is ZEROES. For the "pie is a real true number" POV, sin(pie) is not, not, not 4*2**-64 -- it's that number with all the (subtracted) digits of pi.
I thought I could get an example of this with comparing C and Java on an Intel box, but gcc on my Mac is too clever and keeps calling a subroutine instead (Apple was once very, very picky about floating point, and it would not surprise me if this is special to them).
Single vs double rounding, in fused vs cascaded multiply-add operations.
Range reduction in trig functions (Intel hardware only uses a 68-bit PI, this causes problems sometimes).
Double-rounding when converting FP precision (e.g., 64-bit mantissa to 53, or 53 with extended exponent to 53 with regular exponent when the mantissa goes denorm).
Conversion to/from string representation.
Issues with "constructive reals" (a=b? is not necessarily an answerable question -- you might need to look at "all" the digits in order to answer "yes").
Distributive law DOES NOT HOLD -- a * (b+c) != a*b + a*c
Form a company (Limited Liability Corporation) to run the camera, which sells the footage for a nominal fee. LLC is on the hook for not getting a pro license, but sadly, they have no assets.
At least, that's how it's done in property development. A multi-lot developer in our town, has an LLC for each address in the package.
I don't recommend actually taking this advice, this is merely how the Big Boys do it, it still takes lawyers.
Corporate CEO not entirely honest? Oh, my, bring the smelling salts, I feel faint.
I think it would be different if he were selling addictive poison, cooking the planet, or selling tainted food. Otherwise, this is just standard issue corporate deception.
As I see it, there are several things going on that he doesn't want to talk too much about. First and foremost, above and beyond the slowdown, is that there are no standards for Flash advertising. It's a race to the bottom, and it causes everyone with a modicum of technical skills (i.e., 90th percentile or better among Apple's customers and would-be customers, I think) to install a Flash Blocker. We do this, why? Because it makes browsing better. How can Apple get that same improvement for the other 90%? One option is, he can ban Flash, and promote alternatives for popular Flash applications while he has the market ability to do it. Then there's the slowdown, and the desire to control the platform's evolution, and I would be surprised if he were not looking into the problem of HOW do you present advertising that doesn't annoy people. The App Store may be a model for that, too.
Another obvious problem, not discussed, is the difficulty of virus-proofing the platform. It's not a matter of "user education" -- saying that, is another way of saying, "won't happen, ever". A side-effect of the no-interpreters rule, is that the only "programs" that run, are those that are eyeballed and approved at the app store. Flash, as a programmable widget implicated in previous hacks (e.g., the Flash+UPNP attack on DNS from home routers) is certainly on the list of things to avoid. Acrobat Reader in its full form (recently the cause of a PDF-hosted hack) is another bad guy -- another Adobe product. I don't know quite why Jobs doesn't talk about this (does this make relations with Symantec and McAfee difficult? Is this like talking about death in a hospital?), but it's an obvious reason to rule with an iron hand.
So, I think it's just plain silly to complain about this. He's got good reasons, he's not talking about them, and I think the not-talked-about reasons are much more interesting than the official ones, or the complaints about how this chokes off innovation.
And by-the-way, here's one way to think about what Apple might do, that has not much effect on the consumer, might make life better for them, but would be devastating to other corporations. Supposing that Apple did for the iPod/iPad/iPhone, what I like to do on my home router, which is just plain block all the popular advertising sites. If you want your advertising to be seen by Apple customers, you go through Apple. Why should I complain, that I am deprived of the ability to see ads that I already take actions to avoid? If Apple does a better job with the advertising, bully for them. But the advertisers, whoo-hoo, won't that be fun?
Broadcast PBS Friday nights for the yelling heads, sometimes nature shows. Colbert Report and Daily Show over the intertubes for the news. Otherwise, no cable, no satellite TV.
Perhaps they will all go out of business; what little I see of TV (usually on business trips), suggests that they deserve it.
The thermal energy balance for a solar panel runs vastly in the other direction. If our solar panel is pure black, and 14% efficient, then for each kWh of electric power that comes out, there are 7 kWh of heat that were absorbed and radiated. But each kWh it generates it eliminates the release of 1.4 pounds of CO2, which during its lifetime in the atmosphere will absorb 210,000 kWh of heat. So the energy balance for the solar panel (when it's connected to the US grid) is about NEGATIVE 209,993 kWh(heat) per kWh(electric) -- since some fossil power plant somewhere is being turned down based on its generation.
And if we're that concerned about albedo, we can make our roads, roofs, and parking lots whiter.
Firewalls are a good idea, but they can also be used to generate lame excuses. I did complain to one site about a Flash add (designed to thwart Click-to-Flash, I think) that filled the screen and interfered with reading the site, unless flash was enabled (at least, that was what I could determine). I bitched at them about this, pointed out that I was ok with static advertisements, and got the firewall-runaround. Bitched about the behavior of their corporate parent, got the firewall runaround.
So I got rid of their bookmark, and I don't miss them.
I drive a Honda Civic. My wife drives a Toyota Camry, and was once rear-ended (stopped at a red) by a Ford Expedition (chatting on a phone, almost certainly). The car was repairable, and the passenger compartment was undeformed. It was only slightly inconvenient, though rather expensive for the Expedition's owner's insurance company (lots of work at the body shop, a rental car for the duration, that sort of thing).
And when I am not driving a Honda Civic (like today) I ride a cargo bicycle, so I am well aware of the risks of small vehicles.
What I observe, and I observe a lot while cycling, is that (some) people in cars don't like to stop. They game yellows, they run red lights, they roll through stops, they roll through right-on-reds, and then they complain a whole bunch when they get caught doing it. It usually turns out ok, but sometimes it doesn't (at least 2 pedestrians killed in crosswalks in our little town in the last 10 years -- and for comparison, other alarming causes of mortality in the last two years include 2 by gun in a murder-suicide, and 4 by Al Qaeda on 9/11. So from simple arithmetic, sloppy driving is a Bid Deal). As a practical matter, you're in a car, you are wearing a suit of armor, and cutting corners at an intersection creates a risk of harming a pedestrian, that you may or may not have noticed before you decide to run a yellow that is really much closer to red. If you don't like the risk of being rear-ended, you can usually mitigate it by slowing down before the intersection.
50mph @ 100 ft has you through the intersection in 2 seconds, long before it turns red. In that case, you keep rolling. What I see, in practice, is people who know that the light will be yellow for quite a few more than 2 seconds, and gaming it down to the last fraction of a second. I saw a batch of them this morning, who were still rolling (not stopped/blocked) through from a left turn after my light had turned green (which, given a second or two of all-red following their ample yellow, that they just didn't feel like waiting).
Our laws are relatively sensible, but they tend to be lackadaisically enforced, which leads to a sort of relaxed approach to things like stopping, stopping at stop lines, speed limits, and following distance. Add to that, in the Boston area, that the human-factors school rejects are in charge of planting trees in front of signs, ensuring that sight lines are obstructed, removing street signs, and ensuring that turn-only indications are placed so that you will know that you are in the wrong place only after you have no way of correcting your error.
I drive an old car, and if I see a yellow and can stop, I usually do (not a panic stop, just a stop). It is common for people behind me in an adjacent lane to whiz on through, and I think that about 1 time in 4, someone will cross the stop line after the light has (just) turned red. People learn to game the light timing.
Slashdot Mirror
's wallet.
Sure, but consider some of the recent Texas governors. Governor Goodhair, and Bush? Yee. haw.
Didn't know that; that's somewhat good news. Nonetheless, I'd like to stretch it out as much as possible (I can trace some tiny part of my ancestry back to William the Conqueror's apple-keeper -- it's good to take the long view, right?) The claims made for thorium reactors are interesting, to say the least, and we've got a lot of it.
You are aware, that without breeder reactors, we're not terribly far from "peak uranium", right? Something like a hundred years at current consumption, which is much lower than the replace-coal consumption rate.
Not just France, however. It's not just nukes.
Y2K Census data if you take the data for metro areas (this is conservative) sort by density, then compute the cumulative population, you find that:
Out of the Y2K total of 281 million people, about 20% (60 million) live in metro areas more dense than 2000 people per square mile. Over half live in places denser than 777/square mile, which may not be dense enough. To make the case that we're not like Europe, we'd need similar numbers, but it seems safe to say that an awful lot of people live in decently dense places (note that Atlanta metro (692/mi^2) did not make the top half -- they are at the 176M cumulative mark)
Because these are metro areas, there is still room for tighter and looser clustering -- so for example, there are surely parts of the SF/Oakland Metro area that are too spread out for commuting (there is the small matter of the Bay Bridge), but there are also tight clusters within less-dense metro areas -- for example, the Boston Metro area is at the 143 million mark (last 40 million above) at 926 ppl per square mile, but I start my commute in one town of 4900/mi^2, cross a town of 7900/mi^2, cross a town of 1800/mi^2, and end in a town of 2100/mi^2. This suggests that metro areas may be too granular, but it also suggests that what matters more than density, is distance to work; I would not be surprised to discover that there's a higher percentage of people working-from-home in some of interesting, very-low-density places.
The median commute distance in the US (as near as I can tell, it is hard to determine exactly) is somewhere around 11 miles. This may be a more important number than mere density, because some of the big metro areas have expensive housing and long-distance commutes (SF/Oakland, in particular, as well as NY, and Boston, for that matter). But, a 10-mile commute is doable by bike -- in particular, doable by an old fat guy on a cargo bike. I knew this when I started, because I used to ride 10-mile time trials as a kid and they were no big deal.
I disagree, very much. I know one climate scientist, and I know quite a few people who do that sort of modeling (it's all variations on finite elements, with various hard parts stirred in). Some of them are doing stuff that is completely far-out, meaning, trying to model the process by which a star goes nova. The obvious question is figuring out how the model diverges from reality, how to test that, and how to fix it. That's pretty much their focus. As far as agendas go, I suspect it is the other way around -- if the models keep telling you that we have a serious problem, eventually you might start telling people that it looks like we have a serious problem.
The coal industry, in contrast, has a duty to their shareholders to promote the further profitability of the coal industry by whatever legal means there are, and they are not required by law to tell the truth except in certain special circumstances (SEC reports, testifying under oath, that sort of thing).
Here's some reasonable data somewhat supporting your solar intensity hypothesis. The problems are that (1) now that we can observe intensity directly, we haven't observed large enough changes (2) your assertion about the relative warmth of the MWP seems to be not quite correctn and (3) where's the huge pile of sunspots?
I found no problems in anything that you referenced, because you referenced nothing. If you want to make a case, please support it. The "standard sources" (Wikipedia, top hits in Google) don't.
1) it depends upon what the meaning of is, is. (yes, I did use present tense. I should have been vaguer. You're being pedantic, and you know it.)
2) The symptoms-addressing is more of a future problem than a present problem, so it has the same 20-year horizon. The one thing that might make sense to address now/ASAP, is warming in the arctic. Intuition says that's going to have nasty feedback effects in the future. However, if you decide that you're addressing symptoms, intuition is hardly a reliable guide, and it seems like you are buying heavily into the very models that we're not dead sure of -- what action addresses what symptoms, what is the magnitude of the action, what are the predicted side-effects? We might end up, saying balancing ozone destruction against warming, or acid rain.
3) If we won't have a fossil fuel replacement in 20 years, then we should start developing one in 1980. Failing that, now. I would, in fact, like to see the market work on this one, and the best way I know of to get the market moving is to convert the hypothesized external cost of carbon emissions, integrated over all modeled futures, into a tax, and phase it in on a schedule that we hope tracks the rate of non-GHG energy innovation, or maybe pushes it at little bit. I'd rather not have the government choosing favorites, except perhaps proven ones (things show to work in Europe where they already have half our footprint), and ones to help in the 3rd world.
It's the integration-over-all-outcomes parts that's the real problem. Just as certain banks and hedge funds recently did, I very much get the impression that lots of people are only considering the most-likely outcomes. For the US, most-likely is not-that-bad, and for people (like me) who live in the Northeast, or many Canadians, well, it might even be positive (shorter winter, summers no hotter than what I grew up with in the South, ok). But the tail of outcomes contains some extremely high-cost outcomes of distinctly non-zero probability, at least using the models that we have now. Their cost-weighted measure is enormous -- if we trust the models. And do we trust the models, more than, say, coal-industry spokesmen?
I am not so sure of this (and note that you are making an essentially economic prediction about the future, and we're not too good at those, either).
If we're serious about GW, we start with an increasing CO2 tax, beginning at somewhere between $10 and $50 per ton of CO2 (think, burning 100 gallons of gasoline). You'll notice the price differential, but we've had worse fluctuations in recent years. And it goes up, and everyone knows it goes up. Europe is an existence proof for how we can live pretty well with half the CO2 footprint, and high gas prices.
At a certain CO2 tax, alternatives become economically interesting. Don't fart around with random subsidies and targeted stuff like that, just make it clear what will happen, and let the market go at it. DO see about a national effort to upgrade the power grid.
But, such a tax, certainly means the end of the coal industry, probably in my lifetime. They won't be able to compete, unless they can make the whole sequestration thing work. And they might.
I have enough trouble following my own field; I know at least one climate scientist personally, and he's well and truly convinced. But, every time someone has put forth a contrary theory, if/when I take the trouble to look into it, it falls apart. So if there are better contrary theories, by all means advertise them (links, perhaps?) The massively funded PR campaign is surely working against good science here, since I am certain that they will indiscriminately fund scientific-sounding cranks.
There is this other problem, which is that in any naive model, increased CO2 absolutely increases temperature, because it really is a greenhouse gas (transparent to many wavelengths, blocks various IR bands). So a good theory would not only explain observed warming in ways that did not depend on CO2, it would also demonstrate (or a companion theory would demonstrate) why CO2 does not produce warming in the world that we live in. (And obviously, we know we are not living in the naive model.)
This is somewhat different. The defenders of the Static Universe did not have Sagans and Sagans of dollars depending on the acceptance of the theory. If we took global warming as a drop-dead-serious problem, it would be the end of the coal industry, and business would be very different for the oil industry (plastics, we still need plastics). The auto industry not be on life support; it would be dead and buried.
There is, in addition, the problem that we already have nice solid evidence of an earlier spring (the yearly spring dip in the Keeling Curve is beginning earlier), and we have a mechanism dead to rights for why increased CO2 should make the earth warmer. The science on this is not weak; our main problem is that we are trying to get data out of a noisy system, and there's no control. In contrast, the it's-not-happening crowd does not have a good explanation for why it should not be happening, nor do they have good data showing that it is not happening (noisy data has the annoying property that it proves nothing for nobody, neither presence or absence). They do sometimes say things that sound scientific, but those typically get holes punched in them with a quick visit to Wikipedia. So, not really.
As far as "trying to shut up the other side", well, yeah, it gets f*cking frustrating, if you're not just arguing with other academics, but instead have to deal with a well-funded FUD and PR campaign, that can even afford to buy senators. This is not an ordinary "scientific debate".
Catastrophic cancellation -- suppose you have C1 = a + bi, C2 = x + yi. Multiplying them yields (ax - by) + (ay + bx)i. Done "naively", those embedded subtractions/additions can lead to excess cancellation. The "easy" way to deal with this is to do the intermediate multiplications (ax, by, ay, bx) into higher (doubled) precision, do the add/sub in the higher precision, and then round down to get your answer. Works pretty well for single (because double is always available), not so well in double (because quad is sometimes architected, but not supported except in emulation). There are probably some tricks for doing this well with IBM Power's fused multiply-add.
Range reduction is substantially more subtle, and it requires that you understand a particular point of view. That POV is that each machine floating point number is exactly what it is -- the representation of pi (the 64-bit mantissa approximation that you get in 80-bit Intel FP) is expressly, NOT PI, it is a different number, very close to PI. So, consider sin(PI+x) for a moment, for very small x. That should be very nearly equal to -x. Now, suppose you take a 64-bit mantissa approximation of PI, call that "pie". I happen to know that it is slightly larger than PI, hence the "PI+x" formulation (bits 65-68 = hex C) (I may be making sign errors here). Suppose you want to computer sin(something), where something happens to be pie. The first thing you notice is that it is (a) larger than PI and (b) also larger than the 68-bit approximation of PI. So, either way, you need to do range reduction, subtracting either a sufficiently large approximation of PI, or subtracting a 68-bit approximation of PI. If you subtracted true PI, what you get is 64 (63?) zeroes in the mantissa, followed by 1 at the 64th position (because pie is rounded up) minus all the following digits of true PI. If, on the other hand, you subtract the 68-bit approximation of PI, you get 64/63 zeroes followed by binary 0100 (16-12), and all the rest is ZEROES. For the "pie is a real true number" POV, sin(pie) is not, not, not 4*2**-64 -- it's that number with all the (subtracted) digits of pi.
I thought I could get an example of this with comparing C and Java on an Intel box, but gcc on my Mac is too clever and keeps calling a subroutine instead (Apple was once very, very picky about floating point, and it would not surprise me if this is special to them).
Form a company (Limited Liability Corporation) to run the camera, which sells the footage for a nominal fee. LLC is on the hook for not getting a pro license, but sadly, they have no assets.
At least, that's how it's done in property development. A multi-lot developer in our town, has an LLC for each address in the package.
I don't recommend actually taking this advice, this is merely how the Big Boys do it, it still takes lawyers.
Corporate CEO not entirely honest? Oh, my, bring the smelling salts, I feel faint.
I think it would be different if he were selling addictive poison, cooking the planet, or selling tainted food. Otherwise, this is just standard issue corporate deception.
As I see it, there are several things going on that he doesn't want to talk too much about. First and foremost, above and beyond the slowdown, is that there are no standards for Flash advertising. It's a race to the bottom, and it causes everyone with a modicum of technical skills (i.e., 90th percentile or better among Apple's customers and would-be customers, I think) to install a Flash Blocker. We do this, why? Because it makes browsing better. How can Apple get that same improvement for the other 90%? One option is, he can ban Flash, and promote alternatives for popular Flash applications while he has the market ability to do it. Then there's the slowdown, and the desire to control the platform's evolution, and I would be surprised if he were not looking into the problem of HOW do you present advertising that doesn't annoy people. The App Store may be a model for that, too.
Another obvious problem, not discussed, is the difficulty of virus-proofing the platform. It's not a matter of "user education" -- saying that, is another way of saying, "won't happen, ever". A side-effect of the no-interpreters rule, is that the only "programs" that run, are those that are eyeballed and approved at the app store. Flash, as a programmable widget implicated in previous hacks (e.g., the Flash+UPNP attack on DNS from home routers) is certainly on the list of things to avoid. Acrobat Reader in its full form (recently the cause of a PDF-hosted hack) is another bad guy -- another Adobe product. I don't know quite why Jobs doesn't talk about this (does this make relations with Symantec and McAfee difficult? Is this like talking about death in a hospital?), but it's an obvious reason to rule with an iron hand.
So, I think it's just plain silly to complain about this. He's got good reasons, he's not talking about them, and I think the not-talked-about reasons are much more interesting than the official ones, or the complaints about how this chokes off innovation.
And by-the-way, here's one way to think about what Apple might do, that has not much effect on the consumer, might make life better for them, but would be devastating to other corporations. Supposing that Apple did for the iPod/iPad/iPhone, what I like to do on my home router, which is just plain block all the popular advertising sites. If you want your advertising to be seen by Apple customers, you go through Apple. Why should I complain, that I am deprived of the ability to see ads that I already take actions to avoid? If Apple does a better job with the advertising, bully for them. But the advertisers, whoo-hoo, won't that be fun?
I mean, really. The free software guys care about something that is irrelevant to most of Apple's customers, and vice-versa. What's the point?
Broadcast PBS Friday nights for the yelling heads, sometimes nature shows. Colbert Report and Daily Show over the intertubes for the news. Otherwise, no cable, no satellite TV.
Perhaps they will all go out of business; what little I see of TV (usually on business trips), suggests that they deserve it.
The thermal energy balance for a solar panel runs vastly in the other direction. If our solar panel is pure black, and 14% efficient, then for each kWh of electric power that comes out, there are 7 kWh of heat that were absorbed and radiated. But each kWh it generates it eliminates the release of 1.4 pounds of CO2, which during its lifetime in the atmosphere will absorb 210,000 kWh of heat. So the energy balance for the solar panel (when it's connected to the US grid) is about NEGATIVE 209,993 kWh(heat) per kWh(electric) -- since some fossil power plant somewhere is being turned down based on its generation.
And if we're that concerned about albedo, we can make our roads, roofs, and parking lots whiter.
Strictly speaking, they are tracking your car's movements.
Clearly, you need a bicycle. Or maybe, a jetpack.
Books on tape. Harry Potter, Jim Dale, he's pretty good. Avoid Redwall. We tried a The Hobbit BoT once, the reader was a tad ponderous.
Firewalls are a good idea, but they can also be used to generate lame excuses. I did complain to one site about a Flash add (designed to thwart Click-to-Flash, I think) that filled the screen and interfered with reading the site, unless flash was enabled (at least, that was what I could determine). I bitched at them about this, pointed out that I was ok with static advertisements, and got the firewall-runaround. Bitched about the behavior of their corporate parent, got the firewall runaround.
So I got rid of their bookmark, and I don't miss them.
I drive a Honda Civic. My wife drives a Toyota Camry, and was once rear-ended (stopped at a red) by a Ford Expedition (chatting on a phone, almost certainly). The car was repairable, and the passenger compartment was undeformed. It was only slightly inconvenient, though rather expensive for the Expedition's owner's insurance company (lots of work at the body shop, a rental car for the duration, that sort of thing).
And when I am not driving a Honda Civic (like today) I ride a cargo bicycle, so I am well aware of the risks of small vehicles.
What I observe, and I observe a lot while cycling, is that (some) people in cars don't like to stop. They game yellows, they run red lights, they roll through stops, they roll through right-on-reds, and then they complain a whole bunch when they get caught doing it. It usually turns out ok, but sometimes it doesn't (at least 2 pedestrians killed in crosswalks in our little town in the last 10 years -- and for comparison, other alarming causes of mortality in the last two years include 2 by gun in a murder-suicide, and 4 by Al Qaeda on 9/11. So from simple arithmetic, sloppy driving is a Bid Deal). As a practical matter, you're in a car, you are wearing a suit of armor, and cutting corners at an intersection creates a risk of harming a pedestrian, that you may or may not have noticed before you decide to run a yellow that is really much closer to red. If you don't like the risk of being rear-ended, you can usually mitigate it by slowing down before the intersection.
50mph @ 100 ft has you through the intersection in 2 seconds, long before it turns red. In that case, you keep rolling. What I see, in practice, is people who know that the light will be yellow for quite a few more than 2 seconds, and gaming it down to the last fraction of a second. I saw a batch of them this morning, who were still rolling (not stopped/blocked) through from a left turn after my light had turned green (which, given a second or two of all-red following their ample yellow, that they just didn't feel like waiting).
Our laws are relatively sensible, but they tend to be lackadaisically enforced, which leads to a sort of relaxed approach to things like stopping, stopping at stop lines, speed limits, and following distance. Add to that, in the Boston area, that the human-factors school rejects are in charge of planting trees in front of signs, ensuring that sight lines are obstructed, removing street signs, and ensuring that turn-only indications are placed so that you will know that you are in the wrong place only after you have no way of correcting your error.
I drive an old car, and if I see a yellow and can stop, I usually do (not a panic stop, just a stop). It is common for people behind me in an adjacent lane to whiz on through, and I think that about 1 time in 4, someone will cross the stop line after the light has (just) turned red. People learn to game the light timing.