To get even acceptable raid-5 performance, you need large cache. Linux can use system memory, but hardware raid solutions need their own cache, on some cards 1GB or more, sometimes battery backed so that data can be written out t. That, and the processor are not cheap (though they are not terribly expensive). Combine that with relatively limited market and lack of economies of scale, and you have somethings costing a few hundred dollars.
Plus, the market leaders have a competative advantage in percieved reliability and trustworthiness that is particularly important to their customers, which allows them to charge more than a potential competator would be able to.
Matlab is much faster to program in than lower level languages such as C++ and Java. Think of it as perl for numerical computing. For doing matrix math, Matlab usually stacks up pretty well against lower level languages. Of course, you can do as well in C++ (or whatever), but Matlab is usually fast off the bat.
Also, if you are working with scientists, rather than computer "scientists" availability of Matlab programmers far exceeds java programmers.
Matlab can be run in a terminal, though not quite as nicely at octave (since it can't use readline). Furthermore, even in the workshop, you can set your editor to emacs rather than the built-in editor.
Almost all of matlab toolboxes are written in matlab -- you can read and modify them as you need.
I love octave, and use it extensivly, but Matlab is technically far superior, both in functionality and performance (most of the time), though octave tends to have cleaner/more flexible interfaces to the functionality that does exist. The license management is annoying, though (not to mention expensive). Luckily, our university has a site license, so it doesn't cost us so much.
Of course, octave loads much faster (even when you don't load matlab's JVM).
I believe, but am not sure, that the engine on the JSF stays fixed. Regardless, it definitely uses a lifting fan to provide the bulk of the lift. The Boeing design candidate used a rotating engine assembly which was simpler to design but gave considerably inferior performance.
AFAIK, neither of these are price fixing. Price fixing is a form of collusion between two nominally competing parties, in order to set prices above the market value. If MS and Netscape had collued to set the price of a browser at $50, that would be price fixing.
Selling something below cost can be an anti-trust violation (for example, predatory pricing: sell it cheap now, so you can raise the price when the competition goes under), but I don't believe it can be applied to GPL software, since it can't be effectively used to make or maintain a monopoly above the market price. In fact, free software (of some sorts, at least) work to increase market efficiency by lowering the barriers to entry for competition. This actually works to prevent the formation of monopolies.
Most people don't have a problem with the patent system because most people do not imagine that it can affect them. These people do not support the patent system either, they are indifferent. Even so, I can't count the number of people I have talked to who think patents are fine, but are amazed to hear about patents such as Amazon's 1-click patent.
I would say that most software developers believe software patents are dumb. That the other 99% of the population doesn't care is not a convincing argument that they should be allowed.
The real issue is "allows for more than 4 GB of address space". PAE allow for physically addressing up to 64 GB of memory (albiet with a performance penalty), but an application can only address 4 GB at a time. This may be a limiting factor for database and scientific applications, and also is inconvenient if you wnat to mmap large files (such as block devices or virtual drives) for other purposes.
Furthermore, in massively multi-threaded applications, you can run out of virtual address space for the program stacks. The spacing of the stack base address must be greater than the largest stack any thread will ever have, which if you have thousands of threads can use up a lot of virtual address space. I leave it as an excercise whether this sort of application architecture is ever a good idea.
A 64 bit OS running on a 64 bit CPU allows more efficient access to all of physical memory + gives applications the ability to address much more virtual memory (which can be useful even if physical memory is 4GB).
Re:Investment in superconducting vs. alt. fuel...
on
Quantum Wires
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· Score: 2, Insightful
I think you overestimate the amount of funding being poured into alternative energy research.
Re:EMR from high tension power lines?
on
Quantum Wires
·
· Score: 1
Many AC-DC converters are relatively efficient (> 90% efficiency). Since we won't be doing power distribution with 5VDC, we would still need several levels of voltage step-down, and computers would still need to convert the "home" intermediate voltage DC to the 12, 5, and 3.3 that they need. Given that, I suspect we are better off staying with AC.
Furthermore, there is no good replacement for AC motors, which are considerable more efficient than DC, and generate less EMI.
My point could have been substantially more clear, but the point was that you cannot directly compare the lengths of a bridge and an elevator. To make a 100 mile long suspention bridge, for instance, you would need fantastically tall supports at either end. Also, a substantial fraction of the weight of the bridge is not the primary load-bearing mechanism (ie, the actual bridge). With a space elevator, almost all of the mass is in the load-bearing cable. Without doing any numbers, or having much experience with civil engineering projects of this magnitude, I would guess that constructing a 50 mile suspention is of comprable engineering difficulty to building a space elevator. The parent of my post suggested building a bridge from Mexico to Singapore (or something like that), which is absurd.
I don't believe so. It turns out that this is still not enough to sue someone for. You are allowed to have different standards for appearance for men and women. You can also prohibit men from wearing skirts, or if you really wanted to, women from wearing pants.
In practice, (I am not sure what the legal precedent on this is) it is easier to discriminate on such bases when you are working in a service job (he was a checker at a grocery store). Their claim was that they and their customers demanded a professional appearance and that men with long hair did not fit that. It is also possible that it was just him (he had the standard, nasty "CS hair" that so many nerds have at one point in their life).
Another grocery store in town would not hire people with visible body art except for girls with 2 earings. Same story.
It seems likely that the estimates of 12 years are a little optimistic for something of this scale, but I would certainly like to be wrong on that count. However, if we spend 5 billion dollars on this and we end up developing the technology to cheaply produce super-strong cables out of carbon nanotubes, I say it is money well spent, even if there is no space elevator.
If it works, a space elevator is THE best way to get things in and out of orbit. Also, I am sure you realize it, but your bridge analogy is specious at best. Building long bridges and tall elevators are not comprable projects.
Anonymous opinions are worthless. Anonymous facts are not. Of course, in the real world, the difference between facts and opinions is somewhat blurred, but you can have valuable anonymous speech.
Obviously it is nice to have an identity attached to information to help determine how credible it is, but even with no faith in the accuracy whatsoever, it can trigger independent research. This is the same as when information comes from a well-known but untrusted source.
Whenever one of the nut-job religious extremist organizations says anything about sex (birth control, STDs, homosexuality, premarital sex) I assume that their is some grain of truth in it, but has been distorted beyond recognition. However, I usually do further research to determine what the truth is (which is often different than my previous conceptions, even if it bears almost no relation to the tripe spouted by said organization).
You can't lawfully do that. If someone found out, they could sue you and whoever posted the information for defimation. It is the reason why former employers never can say anything bad about a former employees.
Only if the information is false. The truth is an absolute defense against all defamation and libel suits. Even so, I doubt the prospective employer can be held accountable in most cases. However, a person (or former employer) saying something bad that is false (or not provably true) about someone, which causes them to not get hired is definately actionable.
Now, there are certain types of information which you are not allowed to make hiring decisions on, but those are a specifically enumerated list (age, race, sex, religion, marital status, intent to have children, medical conditions, etc.). Asking about those on a job application is illegal, and if you can show that a prospective employer found this information on Google and probably used it to discriminate against you, then you have a suit.
If, however, I use google to find a web page you wrote 5 years ago about how you hate puppies, and do not hire you, I am almost certain that is legal. I have a friend who was essentially fired for not cutting his hair (he was an hourly employee and they refused to schedule him any hours until he cut it). There is no legal recourse unless you can claim that the discrimination falls under one of the recognized and protected categories (ie. "my religion prevents me from cutting my hair").
Also, consider that you can be denied employment for refusing or failing a drug test, even though your guild has not been legally proven. I personally think this is a travesty, but it is not illegal.
It is evil to not treat people with respect, such as by deceiving them for profit. When I search for something on google, I expect to receive their best guess as to what I am looking for, and to deliberately manipulate the results to give me the page they *wish* I was looking for is dishonest and therefore evil.
Luckilly, google realizes that their long-term viability is dependent on people like me trusting them to behave honsestly. If they cease to behave in an honorable fashion, they will eventually lose credibility, then users, and finally advertizers. Thus, in the long run, don't be evil is also good business practices.
Too many people, caught up in the glitz of capitalism and the tremendous benefits it has provided to us, have come to embrace the attitude that "if it is possible and legal, it is OK". I understand (though do not approve of) this when it is the attitude of people running businesses who are judged soley on their net income, but when they very people getting screwed by these sort of attitudes -- which includes everyone who has been duped into overpaying for a bad product -- justify the behaviour of those businessmen by saying "they are in business to make money, not help me" I am amazed and saddened.
In many applications the length of the serial part (the part of the program during which only 1 CPU may be executing) grows slower than the parallel part with the problem size. Thus, for large problems, the serial part becomes a small (but not usually insignificant) part of the computation.
Note that the relative size of the serial part of a program is independent of the ease or parallelization. The size of the serial part determines how many processors can be committed to the task before reaching diminishing returns. Compiling tends to have relatively long serial sections compared to many applications. The ease of parallelization has to do with the degree of synchronization required by the parallel part, and determines how closely connected the CPUs must be for the gain from adding CPUs to exceed the increased syncrhonization overhead.
Compiling code is embarassingly parallel (it can be distributed over almost any network) but has a large serial section (linking). Therefore, it easily scales even on a slow network, but tapers off once linking starts to take over. Other applications fall in all four quadrants of this plane.
It isn't that we'll never need more than 120/160/250/320/400/500 GB of storage, it is just that most users don't need that *right now*. As mentioned, the WD raptor drives are very popular despite having much lower maximum capactities. We need some new developments in some or all of processors, network bandwidth, video cards, busses, and storage interfaces before it will become practical for most people to take advantage of even the capacities available now.
Some additional speed would be nice, but realistically, after startup my computer is rarely disk speed limited, since I have enough memory. For most people it would not be worth trading the increased noise and failure rate as well as decreasing reliability to get 15K rpm drives.
I frequently find email that at least claims to be illegal all the time.
I am not going to stop using email because of this, even though I believe it is technically illegal for me to receive and/or posses these emails (I don't look at them -- they go directly to the spam bucket most of the time).
Restricting knowledge only serves to retard growth, and keep the 'special ones' in power.
The results are public, just not the copyrighted article. Since tax dollars do not go to the journals, they charge for subscriptions -- print or electronic.
That said, most scientists I know are frustrated by this as well, and do what they can to allow freer access to their work. So, if you want access to almost any scientific article, try the following (in order):
1) Go to the author's web page. Most journals allow authors to put copies of their papers online, and many scientists take advantage of this.
2) Go to a nearby university library. If they don't subscribe to the journal in question, ask a librarian, it may be possible to get it from another university.
3) Go to arxiv.org (formerly xxx.lanl.gov). Many articles are published there as preprints, but may or may not be the final published version.
4) Finally, email one of the authors. In all liklihood, they will be happy to send you a PDF of their article if it is not available via another mechanism.
The restrictions on the dissemination of scientific literature do not stop anyone with even a tiny bit of motivation. Also, a few journals require subscriptions, but allow google to index the full text, which means the whole article may be in google's cache.
Say you have a process in which some sort of radioactive decay generates pairs of photons, and you have a bunch of detectors. The thing you want to measure is P(theta) -- the probability that a pair of photons are emitted at the angle theta. Something like an OGR would be used to arrange your detectors to get the maximum amount of data.
Of course what I described uses a circular array, not a linear array, but the idea is the same.
Fundamentally, a lot of science is measuring power in signals as a function of frequency. If you take a finite series of measurements, the frequencies that you can detect are basically those whose wavelength is 1/N the seperation between two detectors. The more different seperations you have, the more frequencies you can detect, and the better you can reconstruct the signal.
No, you can never conserve energy in a electron-positron anhillation with a single photon, it is always two. If the particles collide "head on", the photons will have equal energy, if their center-of-mass is moving, one will be blue shifted and the other red shifted, but it never goes away.
Slashdot Mirror
To get even acceptable raid-5 performance, you need large cache. Linux can use system memory, but hardware raid solutions need their own cache, on some cards 1GB or more, sometimes battery backed so that data can be written out t. That, and the processor are not cheap (though they are not terribly expensive). Combine that with relatively limited market and lack of economies of scale, and you have somethings costing a few hundred dollars.
Plus, the market leaders have a competative advantage in percieved reliability and trustworthiness that is particularly important to their customers, which allows them to charge more than a potential competator would be able to.
Matlab is much faster to program in than lower level languages such as C++ and Java. Think of it as perl for numerical computing. For doing matrix math, Matlab usually stacks up pretty well against lower level languages. Of course, you can do as well in C++ (or whatever), but Matlab is usually fast off the bat.
Also, if you are working with scientists, rather than computer "scientists" availability of Matlab programmers far exceeds java programmers.
Matlab can be run in a terminal, though not quite as nicely at octave (since it can't use readline). Furthermore, even in the workshop, you can set your editor to emacs rather than the built-in editor.
Almost all of matlab toolboxes are written in matlab -- you can read and modify them as you need.
I love octave, and use it extensivly, but Matlab is technically far superior, both in functionality and performance (most of the time), though octave tends to have cleaner/more flexible interfaces to the functionality that does exist. The license management is annoying, though (not to mention expensive). Luckily, our university has a site license, so it doesn't cost us so much.
Of course, octave loads much faster (even when you don't load matlab's JVM).
I believe, but am not sure, that the engine on the JSF stays fixed. Regardless, it definitely uses a lifting fan to provide the bulk of the lift. The Boeing design candidate used a rotating engine assembly which was simpler to design but gave considerably inferior performance.
AFAIK, neither of these are price fixing. Price fixing is a form of collusion between two nominally competing parties, in order to set prices above the market value. If MS and Netscape had collued to set the price of a browser at $50, that would be price fixing.
Selling something below cost can be an anti-trust violation (for example, predatory pricing: sell it cheap now, so you can raise the price when the competition goes under), but I don't believe it can be applied to GPL software, since it can't be effectively used to make or maintain a monopoly above the market price. In fact, free software (of some sorts, at least) work to increase market efficiency by lowering the barriers to entry for competition. This actually works to prevent the formation of monopolies.
Most people don't have a problem with the patent system because most people do not imagine that it can affect them. These people do not support the patent system either, they are indifferent. Even so, I can't count the number of people I have talked to who think patents are fine, but are amazed to hear about patents such as Amazon's 1-click patent.
I would say that most software developers believe software patents are dumb. That the other 99% of the population doesn't care is not a convincing argument that they should be allowed.
The real issue is "allows for more than 4 GB of address space". PAE allow for physically addressing up to 64 GB of memory (albiet with a performance penalty), but an application can only address 4 GB at a time. This may be a limiting factor for database and scientific applications, and also is inconvenient if you wnat to mmap large files (such as block devices or virtual drives) for other purposes.
Furthermore, in massively multi-threaded applications, you can run out of virtual address space for the program stacks. The spacing of the stack base address must be greater than the largest stack any thread will ever have, which if you have thousands of threads can use up a lot of virtual address space. I leave it as an excercise whether this sort of application architecture is ever a good idea.
A 64 bit OS running on a 64 bit CPU allows more efficient access to all of physical memory + gives applications the ability to address much more virtual memory (which can be useful even if physical memory is 4GB).
I think you overestimate the amount of funding being poured into alternative energy research.
Many AC-DC converters are relatively efficient (> 90% efficiency). Since we won't be doing power distribution with 5VDC, we would still need several levels of voltage step-down, and computers would still need to convert the "home" intermediate voltage DC to the 12, 5, and 3.3 that they need. Given that, I suspect we are better off staying with AC.
Furthermore, there is no good replacement for AC motors, which are considerable more efficient than DC, and generate less EMI.
My point could have been substantially more clear, but the point was that you cannot directly compare the lengths of a bridge and an elevator. To make a 100 mile long suspention bridge, for instance, you would need fantastically tall supports at either end. Also, a substantial fraction of the weight of the bridge is not the primary load-bearing mechanism (ie, the actual bridge). With a space elevator, almost all of the mass is in the load-bearing cable. Without doing any numbers, or having much experience with civil engineering projects of this magnitude, I would guess that constructing a 50 mile suspention is of comprable engineering difficulty to building a space elevator. The parent of my post suggested building a bridge from Mexico to Singapore (or something like that), which is absurd.
I don't believe so. It turns out that this is still not enough to sue someone for. You are allowed to have different standards for appearance for men and women. You can also prohibit men from wearing skirts, or if you really wanted to, women from wearing pants.
In practice, (I am not sure what the legal precedent on this is) it is easier to discriminate on such bases when you are working in a service job (he was a checker at a grocery store). Their claim was that they and their customers demanded a professional appearance and that men with long hair did not fit that. It is also possible that it was just him (he had the standard, nasty "CS hair" that so many nerds have at one point in their life).
Another grocery store in town would not hire people with visible body art except for girls with 2 earings. Same story.
It seems likely that the estimates of 12 years are a little optimistic for something of this scale, but I would certainly like to be wrong on that count. However, if we spend 5 billion dollars on this and we end up developing the technology to cheaply produce super-strong cables out of carbon nanotubes, I say it is money well spent, even if there is no space elevator.
If it works, a space elevator is THE best way to get things in and out of orbit. Also, I am sure you realize it, but your bridge analogy is specious at best. Building long bridges and tall elevators are not comprable projects.
Anonymous opinions are worthless. Anonymous facts are not. Of course, in the real world, the difference between facts and opinions is somewhat blurred, but you can have valuable anonymous speech.
Obviously it is nice to have an identity attached to information to help determine how credible it is, but even with no faith in the accuracy whatsoever, it can trigger independent research. This is the same as when information comes from a well-known but untrusted source.
Whenever one of the nut-job religious extremist organizations says anything about sex (birth control, STDs, homosexuality, premarital sex) I assume that their is some grain of truth in it, but has been distorted beyond recognition. However, I usually do further research to determine what the truth is (which is often different than my previous conceptions, even if it bears almost no relation to the tripe spouted by said organization).
Only if the information is false. The truth is an absolute defense against all defamation and libel suits. Even so, I doubt the prospective employer can be held accountable in most cases. However, a person (or former employer) saying something bad that is false (or not provably true) about someone, which causes them to not get hired is definately actionable.
Now, there are certain types of information which you are not allowed to make hiring decisions on, but those are a specifically enumerated list (age, race, sex, religion, marital status, intent to have children, medical conditions, etc.). Asking about those on a job application is illegal, and if you can show that a prospective employer found this information on Google and probably used it to discriminate against you, then you have a suit.
If, however, I use google to find a web page you wrote 5 years ago about how you hate puppies, and do not hire you, I am almost certain that is legal. I have a friend who was essentially fired for not cutting his hair (he was an hourly employee and they refused to schedule him any hours until he cut it). There is no legal recourse unless you can claim that the discrimination falls under one of the recognized and protected categories (ie. "my religion prevents me from cutting my hair").
Also, consider that you can be denied employment for refusing or failing a drug test, even though your guild has not been legally proven. I personally think this is a travesty, but it is not illegal.
Out of curiosity, what sort of things have influenced your choices? (obviously, without giving too much away...)
Turns out, anyone can slow their heartrate to zero if a black hole starts to pass through their body.
It is evil to not treat people with respect, such as by deceiving them for profit. When I search for something on google, I expect to receive their best guess as to what I am looking for, and to deliberately manipulate the results to give me the page they *wish* I was looking for is dishonest and therefore evil.
Luckilly, google realizes that their long-term viability is dependent on people like me trusting them to behave honsestly. If they cease to behave in an honorable fashion, they will eventually lose credibility, then users, and finally advertizers. Thus, in the long run, don't be evil is also good business practices.
Too many people, caught up in the glitz of capitalism and the tremendous benefits it has provided to us, have come to embrace the attitude that "if it is possible and legal, it is OK". I understand (though do not approve of) this when it is the attitude of people running businesses who are judged soley on their net income, but when they very people getting screwed by these sort of attitudes -- which includes everyone who has been duped into overpaying for a bad product -- justify the behaviour of those businessmen by saying "they are in business to make money, not help me" I am amazed and saddened.
In many applications the length of the serial part (the part of the program during which only 1 CPU may be executing) grows slower than the parallel part with the problem size. Thus, for large problems, the serial part becomes a small (but not usually insignificant) part of the computation.
Note that the relative size of the serial part of a program is independent of the ease or parallelization. The size of the serial part determines how many processors can be committed to the task before reaching diminishing returns. Compiling tends to have relatively long serial sections compared to many applications. The ease of parallelization has to do with the degree of synchronization required by the parallel part, and determines how closely connected the CPUs must be for the gain from adding CPUs to exceed the increased syncrhonization overhead.
Compiling code is embarassingly parallel (it can be distributed over almost any network) but has a large serial section (linking). Therefore, it easily scales even on a slow network, but tapers off once linking starts to take over. Other applications fall in all four quadrants of this plane.
It isn't that we'll never need more than 120/160/250/320/400/500 GB of storage, it is just that most users don't need that *right now*. As mentioned, the WD raptor drives are very popular despite having much lower maximum capactities. We need some new developments in some or all of processors, network bandwidth, video cards, busses, and storage interfaces before it will become practical for most people to take advantage of even the capacities available now.
Some additional speed would be nice, but realistically, after startup my computer is rarely disk speed limited, since I have enough memory. For most people it would not be worth trading the increased noise and failure rate as well as decreasing reliability to get 15K rpm drives.
I frequently find email that at least claims to be illegal all the time.
I am not going to stop using email because of this, even though I believe it is technically illegal for me to receive and/or posses these emails (I don't look at them -- they go directly to the spam bucket most of the time).
Amen.
The results are public, just not the copyrighted article. Since tax dollars do not go to the journals, they charge for subscriptions -- print or electronic.
That said, most scientists I know are frustrated by this as well, and do what they can to allow freer access to their work. So, if you want access to almost any scientific article, try the following (in order):
1) Go to the author's web page. Most journals allow authors to put copies of their papers online, and many scientists take advantage of this.
2) Go to a nearby university library. If they don't subscribe to the journal in question, ask a librarian, it may be possible to get it from another university.
3) Go to arxiv.org (formerly xxx.lanl.gov). Many articles are published there as preprints, but may or may not be the final published version.
4) Finally, email one of the authors. In all liklihood, they will be happy to send you a PDF of their article if it is not available via another mechanism.
The restrictions on the dissemination of scientific literature do not stop anyone with even a tiny bit of motivation. Also, a few journals require subscriptions, but allow google to index the full text, which means the whole article may be in google's cache.
Say you have a process in which some sort of radioactive decay generates pairs of photons, and you have a bunch of detectors. The thing you want to measure is P(theta) -- the probability that a pair of photons are emitted at the angle theta. Something like an OGR would be used to arrange your detectors to get the maximum amount of data.
Of course what I described uses a circular array, not a linear array, but the idea is the same.
Fundamentally, a lot of science is measuring power in signals as a function of frequency. If you take a finite series of measurements, the frequencies that you can detect are basically those whose wavelength is 1/N the seperation between two detectors. The more different seperations you have, the more frequencies you can detect, and the better you can reconstruct the signal.
Probably they weren't allowed to look at the website at work, so they just sent out the form letter...
No, you can never conserve energy in a electron-positron anhillation with a single photon, it is always two. If the particles collide "head on", the photons will have equal energy, if their center-of-mass is moving, one will be blue shifted and the other red shifted, but it never goes away.