To actually do the variational calculations, you'll need to spacify some basis functions for the solution.
True. In FEM you can enmesh your geometry with different elements, using elementwise different base functions. For our problems however we stuck to finer enmeshments rather than using higher order polynomials as base functions.
Once you get to that point, you're not so far from any other methods for solving the equations.
In the end it is solving large linear systems that have band structure, solving linear equations on the surfaces of the elements and solving nonlinear eqautions if you need information within the elements.
BTW for 1 dimensional problems Finite Differences and Finite Elements yield the same systems of linear equations.
The more important issue is that the variational conceptual perspective is equivalent; but does it actually help the thoughts ?
If you pick up a FEM book by a mechanical engineer (like Oden), they often derive their variational formulations (calculating mechanical stress for example) not from a mathematical point of view, but from a reasoning along mechanical laws (minimization of energy, d'Alembert's principle of vanishing virtual work). So it seems to help them (and annoys the more mathematical folks:)
Another area that I think is important is the expansion of the Universe.
In classical mechanics one learns that the conservation of energy is a consequence of a corresponding symmetry, here the invariance of the system under time (= it should not matter if you do the experiment today or tomorrow).
Thus looking sharply, energy can't be conserved througout the universe, because the universe changes.
I wonder if cosmologist take such effects into account in their models.
The variational formulation is elegant, and variational approaches can good as numerical methods. But is it really adding much to our understanding of atoms and molecules here ?
Can't judge the state of computational chemistry. I have not heard of any big success stories.
Physicists however, especially particle physicists, depend very much on computing.
Or engineering. I did finite element modelling for solving heat diffusion problems, where computations save lots of money because it is cheaper to find out at the desk that some casting of a gas turbine blade won't succeed than after doing this for real with a furnace etc.
The answer for me has always been found in Heisenberg's (sp?) uncertainty principle. He states that you can never know the velocity and the position of an electron at the same moment. What this means to me is that no matter how deep or how complete our physical understanding is, there will always be some bit of uncertainty, if only on the minutest level, that allows us to operate as if we had free will.
The problem we have here is that we try to extrapolate a statement from basic physics, from very simple, idealistic situations, like the path of a particle to very complicated situations, like the free will of an intelligent being. Very easy to be victim to improper generalization.
Example: I am able to write a program for a computer, that pretty much gives determined output, despite the fact that all particles making up my box are subject to the Heisenberg principle.
Of course a cosmic particle might flip some bit, or all particles (and thus my box) might show up on Mars in a second, that is all perfectly legal under present known laws of physics, just extremly unlikely.
I was excited recently to learn that there exists a (more) rigorous derivation of the empirical chemical wisdom that molecules can be described fairly good by considering them built from smaller components (functional groups and atoms of course).
That such a treatment is possible, is not obvious, nature could have been that way, that one had to treat the whole system (like solving the wave equation for all particles at once) in order to make any useful statement at all.
Bader claims that the study of the Laplacian (2nd spatial derivative) of the electron distribution leads to a natural spatial decomposition of a molecule.
I am still surprised, that during my physics studies, I heard nothing about that treatment. You get exposed to Feynman of course, but Schwinger's formulation of quantumn electro dynamics I knew only as possible but not practical alternative. Very interesting to see Schwingers approach at the heart of this AIM theory.
Check this link to see what the CD Index project is using to build a free Internet CD database.
An extension to add Karaoke/sub titling should be found here. I say should, because the link does not work right now (strange), so I provide a link to this mail. This should give you a basic idea until the link is working again.
Sorry Jon, but why should machines become intelligent suddenly? Have there been any fundamental advances concerning the problem of mind and self reference lately, that I missed?
Have you read the anniversary edition of Douglas R. Hofstadter's "Gödel, Escher, Bach"? The foreword was remarkably clear about affairs not having made any real progress on the hard problems during the last 20 years.
But if we have not understood anything about these basic properties of the problem, then we can count only on the technical advances that were really made, thus leaving only the hope, that intelligence might arise spontaneously, if one puts together enough memory chips, computing power and network connections, comparable the critical mass of nuclear fission.
To be honest, I doubt that. (Hasn't worked for Wintel, at least:-) Computers have been around for about 60 years now, some fairly powerful among them. They have become stronger, but not more clever. These things are "Rain men", that can count at an incredible speed, but lack self awareness.
What was the approach of the neural net folks? They built something that resembled natural structures and hoped that their work would show similiar abilities. That is a legitimate approach, but it is still -because the basics are not understood- just a scientific version of guessing and hoping that it will work somehow.
No, my opinion is unchanged. If not by chance, because some "guess" worked, there will be no AI, UI or AL that deserves that rating until someone makes progress on the fundamental problems. There is hope that new computing architectures, like quantumn computing, will let us see the problem from an different, more successful angle, but this is quite some years away.
So I expect just a more of todays technology. Wearable computers, huge networks etc. That will change our life considerably, but it is not close to your catastrophy scenario.
Sorry, but we both should agree that this kind of crime fighting is very questionable.
In a better society, they would have detected that guys massive problem and put him under medical treatment. Here he gets directly sent to jail (maybe not, because he has money).
The same holds for drug problems, where it is not as clear to me, when someone is a criminal or when someone is sick, as it seems to be clear for certain other folks. Compare attitudes in the US and the Netherlands to see what I mean. If it were an easy problem/distinction, we already had a nice solution for treating such people. But it is not. It is a hard problem.
Also, that guy is filthy rich and can hire the attorneys he needs; now think about the little guy who will be caught thusly... Think OJ Simpson..
Someone in this discussion asked if one could enjoy a book by a molester. In the case of OJ I still can enjoy "Capricorn One", because it is such a damned good film. But it gives one the shivers.
On the other hand I would never read one of those Hubbard SciFi book because he did too much bad with his Scientology crap IMHO.
Good I never liked the Java books of this guy, but that was mostly due to his co-author Schildt, whom I personally can't stand. (The effect is comparable to seeing "Demi Moore" on a film poster:)
I am not happy about the agents offering this sicko a bait. Aren't they provoking people who are on a small grate to commit a crime they won't do without opportunity?
Except this, I wonder how stupid those high tech executives are. The Internet is the place where you can be easily identified if you don't use criminal tactics (like hacked accounts) to cover your id. How did he expect to get away with this?
And yes, I am delighted to see one of those, forgive me the strong wording, censorship companies getting problems of this nature. Nice irony.
How about the authors of something that has truly made a difference, and for a long time at that: The Apache Team.
Yes, it would raise the reputation of that price considerably, if they would give it to a deserving recipient of the license-rivaling free software camps, like xfree86.org, Apache team, the BSD folks and maybe one day Mozilla.org.
If RMS feels left out by the Linux community in certain aspects, he should not make the mistake to leave out the other fighters for the common goal!
The OSS community would *never* have gotten to the point it has without the advent of the WWW
I disagree. The most important medium was and is e-mail. Then add ftp servers. For a time the combination e-mail/Usenet was very helpful, while today most development coordination retreated to mailing lists.
Take the GNU project for instance, their WWW site is relatively new compared to their other infrastructure, and most important software (gcc, emacs and the likes) was developed before the WWW became popular. Not to mention the BSD software that was spread on tapes.
The WWW is a very useful media, but e-mail, ftp servers and probably CVS are still more important IMHO.
It's great to use Back Oriface to drop KP into other peoples browser cache, then tell the boss you noticed them browsing something naughty
The attitude of this Anonymous Coward sucks considerably, but he points to an interesting problem - the evidence value of certain digital information.
I am a bit disturbed, because most networks at companies and universities I have worked so far, were pretty unsecure. And if I know how to do so, there are likley to be some other folks around who have that knowledge too.
It is hard to say what I would do, if someone planted comprimising material on my workstation. How should one defend oneself against such. If noone actually saw me downloading, the case will be based on matters of evidence. So I would like to know what kind of digital information actually gets accepted as evidence by court.
I was always surprised to see how e-mail memos were brought up in US trials, like the Microsoft one, or some case when a programmer at Borland left. After all such is so easy to forge, isn't it? Same holds for firewall logs etc.
In the end, depending on your relation with the company, it might damage trust and reputation considerably and ultimately force one to leave anyway.
Knuth is now updating MIX to MMIX, a reduced instruction-set computing machine that more closely mimics computers in use today.
And you can help!
DEK has released updated docs and supporting software. The initial conversion of the programs is done by volunteers. While the bits from Vol. 1 have been passed out to volunteers already, the MIX stuff from Vol. 2 is getting assigned for conversion these days.
I don't know the sociologist definitions of groups and collectives but I think one of the central aspects is that they spend time together and have common interests and goals.
For Slashdot it holds, that this is a place where we exchange information and build opinions together in our discussions. This is enough to form a larger group like that what we describe as Slashdot community, but except for the small group of Slashdot operators, this is not enough to form smaller groups and circle of friends centered around the Slashdot theme.
However Slashdot serves very well as a place where groups are formed and spawned from.
Take the CD Index project for example. It was formed spontaneously after a news on Slashdot was posted that cddb went commercial in a questionable way. A discussion followed, someone offered resources (among them the obligatory mailing list devoted to that goal) and the project started off. With one of that folks I maintain something close to a classical pen pal friendship, mostly centered around our common goal of building up a free CD database, but with exchanges of personal stuff as well.
Slashdot might not only be suited well to spawn technical projects, but considering that we shape opinion here (this is the thing we build together), I would be not surprised to see having politcal groups having their initial point of gathering here (shouting out the geek party or declaration of the rights of cyber citizens or some cybernation).
we all know we want to do something impressive with Linux, IRIX, and our amazing graphics hardware, and we know that technically we can pull it off. Nevertheless, we're not sure if the rest of the SGI structure will be able to "put it out there" with a story convincing enough to put the company back on track.
You may have noticed that many folks here have the impression that SGI is not able to continue IRIX development adequatley. This is by the way, what I thought in 1995 during IRIX 5->6 transition. How do you see the proposal that SGI should focus their OS R&D capacity to open systems like Linux?
Normally I'd post with my account, but today is different -- I'm about to leave SGI myself... I'll miss it.
No more SGI? A catastrophy for every real geek (I'd rather see Apple going down ten times).
At least part of SGI will life on for some years in the incarnation of nvidia.
Sorry, couldn't resist replying that way.:-) Like you wrote:
it's sometimes hard to keep up with everyone
The present pace is amazing. I wonder how other people keep up. They must be more effective or be folks with a lot of free time. Last days I used for tests with XFree86 3.3.5 and thus have now a big pile of unread mails from the various lists that are significant for this topic.
Anyhow, I've little doubt that the SGI implementation of the GLX layer
That is what most people expect. I am glad we have an existing alternative with the free GLX. Even if it ends up thrown away, it gave us so much opportunity to learn.
Interesting is harder to metamoderate than troll
on
Moderation Ideas
·
· Score: 2
Many moderations are questionable, but rarely do I read one and think "What a moron". But they are there, and I want to try to make it happen less.
The stupid moderations are easy to metamoderate.
But it is difficult for me if I get a comment presented for metamoderation that got an interesting or insightful mod and I can't find it exciting at all.
Such happened with an Amiga posting and a Linux posting this morning. In both cases I decided not to change anything, despite thinking that the posts were just normal level and tried very hard to see the postings not from my personal interests but more how Amiga or Linux users might see them. But I am not sure if this is the right thing.
Slashdot Mirror
True. In FEM you can enmesh your geometry with different elements, using elementwise different base functions. For our problems however we stuck to finer enmeshments rather than using higher order polynomials as base functions.
Once you get to that point, you're not so far from any other methods for solving the equations.
In the end it is solving large linear systems that have band structure, solving linear equations on the surfaces of the elements and solving nonlinear eqautions if you need information within the elements.
BTW for 1 dimensional problems Finite Differences and Finite Elements yield the same systems of linear equations.
The more important issue is that the variational conceptual perspective is equivalent; but does it actually help the thoughts ?
If you pick up a FEM book by a mechanical engineer (like Oden), they often derive their variational formulations (calculating mechanical stress for example) not from a mathematical point of view, but from a reasoning along mechanical laws (minimization of energy, d'Alembert's principle of vanishing virtual work). So it seems to help them (and annoys the more mathematical folks :)
In classical mechanics one learns that the conservation of energy is a consequence of a corresponding symmetry, here the invariance of the system under time (= it should not matter if you do the experiment today or tomorrow).
Thus looking sharply, energy can't be conserved througout the universe, because the universe changes.
I wonder if cosmologist take such effects into account in their models.
Can't judge the state of computational chemistry. I have not heard of any big success stories.
Physicists however, especially particle physicists, depend very much on computing.
Or engineering. I did finite element modelling for solving heat diffusion problems, where computations save lots of money because it is cheaper to find out at the desk that some casting of a gas turbine blade won't succeed than after doing this for real with a furnace etc.
The problem we have here is that we try to extrapolate a statement from basic physics, from very simple, idealistic situations, like the path of a particle to very complicated situations, like the free will of an intelligent being. Very easy to be victim to improper generalization.
Example: I am able to write a program for a computer, that pretty much gives determined output, despite the fact that all particles making up my box are subject to the Heisenberg principle.
Of course a cosmic particle might flip some bit, or all particles (and thus my box) might show up on Mars in a second, that is all perfectly legal under present known laws of physics, just extremly unlikely.
Yep, they should use that pic for recruiting.. :)
(I forgot to add :-)
That such a treatment is possible, is not obvious, nature could have been that way, that one had to treat the whole system (like solving the wave equation for all particles at once) in order to make any useful statement at all.
Read this article on Atoms in Molecules by Richard Bader to find out more.
Bader claims that the study of the Laplacian (2nd spatial derivative) of the electron distribution leads to a natural spatial decomposition of a molecule.
Have a look at these great pictures for some simulations based on that AIM theory.
I am still surprised, that during my physics studies, I heard nothing about that treatment. You get exposed to Feynman of course, but Schwinger's formulation of quantumn electro dynamics I knew only as possible but not practical alternative. Very interesting to see Schwingers approach at the heart of this AIM theory.
An extension to add Karaoke/sub titling should be found here. I say should, because the link does not work right now (strange), so I provide a link to this mail. This should give you a basic idea until the link is working again.
I expect it to be released the day after they release the car that runs on plant oil.
Here are the ones you originally wanted:
209.143.242.114, 209.143.242.115
207.5.1.122
Have there been any fundamental advances concerning the problem of mind and self reference lately, that I missed?
Have you read the anniversary edition of Douglas R. Hofstadter's "Gödel, Escher, Bach"?
The foreword was remarkably clear about affairs not having made any real progress on the hard problems during the last 20 years.
But if we have not understood anything about these basic properties of the problem, then we can count only on the technical advances that were really made, thus leaving only the hope, that intelligence might arise spontaneously, if one puts together enough memory chips, computing power and network connections, comparable the critical mass of nuclear fission.
To be honest, I doubt that. (Hasn't worked for Wintel, at least :-)
Computers have been around for about 60 years now, some fairly powerful among them. They have become stronger, but not more clever. These things are "Rain men", that can count at an incredible speed, but lack self awareness.
What was the approach of the neural net folks? They built something that resembled natural structures and hoped that their work would show similiar abilities. That is a legitimate approach, but it is still -because the basics are not understood- just a scientific version of guessing and hoping that it will work somehow.
No, my opinion is unchanged. If not by chance, because some "guess" worked, there will be no AI, UI or AL that deserves that rating until someone makes progress on the fundamental problems. There is hope that new computing architectures, like quantumn computing, will let us see the problem from an different, more successful angle, but this is quite some years away.
So I expect just a more of todays technology. Wearable computers, huge networks etc. That will change our life considerably, but it is not close to your catastrophy scenario.
In a better society, they would have detected that guys massive problem and put him under medical treatment. Here he gets directly sent to jail (maybe not, because he has money).
The same holds for drug problems, where it is not as clear to me, when someone is a criminal or when someone is sick, as it seems to be clear for certain other folks. Compare attitudes in the US and the Netherlands to see what I mean. If it were an easy problem/distinction, we already had a nice solution for treating such people. But it is not. It is a hard problem.
Someone in this discussion asked if one could enjoy a book by a molester. In the case of OJ I still can enjoy "Capricorn One", because it is such a damned good film. But it gives one the shivers.
On the other hand I would never read one of those Hubbard SciFi book because he did too much bad with his Scientology crap IMHO.
Good I never liked the Java books of this guy, but that was mostly due to his co-author Schildt, whom I personally can't stand. (The effect is comparable to seeing "Demi Moore" on a film poster :)
Indeed, I noticed it too. Strange.
Except this, I wonder how stupid those high tech executives are. The Internet is the place where you can be easily identified if you don't use criminal tactics (like hacked accounts) to cover your id. How did he expect to get away with this?
And yes, I am delighted to see one of those, forgive me the strong wording, censorship companies getting problems of this nature. Nice irony.
Yes, it would raise the reputation of that price considerably, if they would give it to a deserving recipient of the license-rivaling free software camps, like xfree86.org, Apache team, the BSD folks and maybe one day Mozilla.org.
If RMS feels left out by the Linux community in certain aspects, he should not make the mistake to leave out the other fighters for the common goal!
I disagree. The most important medium was and is e-mail. Then add ftp servers. For a time the combination e-mail/Usenet was very helpful, while today most development coordination retreated to mailing lists.
Take the GNU project for instance, their WWW site is relatively new compared to their other infrastructure, and most important software (gcc, emacs and the likes) was developed before the WWW became popular. Not to mention the BSD software that was spread on tapes.
The WWW is a very useful media, but e-mail, ftp servers and probably CVS are still more important IMHO.
The attitude of this Anonymous Coward sucks considerably, but he points to an interesting problem - the evidence value of certain digital information.
I am a bit disturbed, because most networks at companies and universities I have worked so far, were pretty unsecure. And if I know how to do so, there are likley to be some other folks around who have that knowledge too.
It is hard to say what I would do, if someone planted comprimising material on my workstation. How should one defend oneself against such. If noone actually saw me downloading, the case will be based on matters of evidence. So I would like to know what kind of digital information actually gets accepted as evidence by court.
I was always surprised to see how e-mail memos were brought up in US trials, like the Microsoft one, or some case when a programmer at Borland left. After all such is so easy to forge, isn't it? Same holds for firewall logs etc.
In the end, depending on your relation with the company, it might damage trust and reputation considerably and ultimately force one to leave anyway.
Start at this link to his home page.
And you can help!
DEK has released updated docs and supporting software. The initial conversion of the programs is done by volunteers.
While the bits from Vol. 1 have been passed out to volunteers already, the MIX stuff from Vol. 2 is getting assigned for conversion these days.
I don't know the sociologist definitions of groups and collectives but I think one of the central aspects is that they spend time together and have common interests and goals.
For Slashdot it holds, that this is a place where we exchange information and build opinions together in our discussions. This is enough to form a larger group like that what we describe as Slashdot community, but except for the small group of Slashdot operators, this is not enough to form smaller groups and circle of friends centered around the Slashdot theme.
However Slashdot serves very well as a place where groups are formed and spawned from.
Take the CD Index project for example. It was formed spontaneously after a news on Slashdot was posted that cddb went commercial in a questionable way. A discussion followed, someone offered resources (among them the obligatory mailing list devoted to that goal) and the project started off. With one of that folks I maintain something close to a classical pen pal friendship, mostly centered around our common goal of building up a free CD database, but with exchanges of personal stuff as well.
Slashdot might not only be suited well to spawn technical projects, but considering that we shape opinion here (this is the thing we build together), I would be not surprised to see having politcal groups having their initial point of gathering here (shouting out the geek party or declaration of the rights of cyber citizens or some cybernation).
You may have noticed that many folks here have the impression that SGI is not able to continue IRIX development adequatley. This is by the way, what I thought in 1995 during IRIX 5->6 transition. How do you see the proposal that SGI should focus their OS R&D capacity to open systems like Linux?
Normally I'd post with my account, but today is different -- I'm about to leave SGI myself... I'll miss it.
No more SGI? A catastrophy for every real geek (I'd rather see Apple going down ten times).
At least part of SGI will life on for some years in the incarnation of nvidia.
it's sometimes hard to keep up with everyone
The present pace is amazing. I wonder how other people keep up. They must be more effective or be folks with a lot of free time. Last days I used for tests with XFree86 3.3.5 and thus have now a big pile of unread mails from the various lists that are significant for this topic.
Anyhow, I've little doubt that the SGI implementation of the GLX layer
That is what most people expect. I am glad we have an existing alternative with the free GLX. Even if it ends up thrown away, it gave us so much opportunity to learn.
The stupid moderations are easy to metamoderate.
But it is difficult for me if I get a comment presented for metamoderation that got an interesting or insightful mod and I can't find it exciting at all.
Such happened with an Amiga posting and a Linux posting this morning. In both cases I decided not to change anything, despite thinking that the posts were just normal level and tried very hard to see the postings not from my personal interests but more how Amiga or Linux users might see them. But I am not sure if this is the right thing.