Re: chaos and the LGP-30
Carlos E Murillo-Sanchez wrote: Will Cooke via cctalk wrote: Theoriginal paper is Edward N. Lorenz, "Deterministic Nonperiodic Flow", Journal of TheAtmospheric Sciences,Vol. 20, March 1963, pp. 130-141. It is at multiple locations in the web. One source is: http://www.astro.puc.cl/~rparra/tools/PAPERS/lorenz1962.pdf At Cornell I took John Guckenheimer's and Steve Strogatz's courses, inaddition to the more EE-focused nonlinear systems course taught byHsiao-Dong Chiang. Really beautiful stuff. carlos. Thanks! Looks like a really interesting read. Will What I think is most awesome, in terms of the role that computing held in this discovery, is that mathematicians since the early 20th century took as granted the idea that the "limit sets" of the trajectories of solutions of time-differential equations were either periodic (also called limit cycles) or singletons (stable or unstable equilibria at a single point in space). Lorenz, through digital integration of a simple third-order differential equation, proved that there were other kinds of limit sets. These limit sets are distributed in space and occupy geometries that we now call "fractal". When they are the result of a chaotic solution to a differential equation, we call them "strange attractors". The first one that was studied was Lorenz's strange attractor, which, in 3D space, looks like a butterfly. I don't know if there is any connection between its shape and the popular "butterfly altering an initial airflow in the dynosaur's era" interpretation (by the way, utterly dumb for anyone who knows about real-life nonlinear dynamical systems). But what I do know, is that mathematicians had to suddenly backtrack 50 years and try to understand how they could be so wrong. And that's how chaos theory emerged. Thanks to numerical computation. carlos. "dinosaur", argh.
Re: chaos and the LGP-30
Will Cooke via cctalk wrote: Theoriginal paper is Edward N. Lorenz, "Deterministic Nonperiodic Flow", Journal of TheAtmospheric Sciences,Vol. 20, March 1963, pp. 130-141. It is at multiple locations in the web. One source is: http://www.astro.puc.cl/~rparra/tools/PAPERS/lorenz1962.pdf At Cornell I took John Guckenheimer's and Steve Strogatz's courses, inaddition to the more EE-focused nonlinear systems course taught byHsiao-Dong Chiang. Really beautiful stuff. carlos. Thanks! Looks like a really interesting read. Will What I think is most awesome, in terms of the role that computing held in this discovery, is that mathematicians since the early 20th century took as granted the idea that the "limit sets" of the trajectories of solutions of time-differential equations were either periodic (also called limit cycles) or singletons (stable or unstable equilibria at a single point in space). Lorenz, through digital integration of a simple third-order differential equation, proved that there were other kinds of limit sets. These limit sets are distributed in space and occupy geometries that we now call "fractal". When they are the result of a chaotic solution to a differential equation, we call them "strange attractors". The first one that was studied was Lorenz's strange attractor, which, in 3D space, looks like a butterfly. I don't know if there is any connection between its shape and the popular "butterfly altering an initial airflow in the dynosaur's era" interpretation (by the way, utterly dumb for anyone who knows about real-life nonlinear dynamical systems). But what I do know, is that mathematicians had to suddenly backtrack 50 years and try to understand how they could be so wrong. And that's how chaos theory emerged. Thanks to numerical computation. carlos.
Re: chaos and the LGP-30
Theoriginal paper is > Edward N. Lorenz, "Deterministic Nonperiodic Flow", Journal of > TheAtmospheric Sciences,Vol. 20, March 1963, pp. 130-141. > It is at multiple locations in the web. One source is: > http://www.astro.puc.cl/~rparra/tools/PAPERS/lorenz1962.pdf > At Cornell I took John Guckenheimer's and Steve Strogatz's courses, > inaddition to the more EE-focused nonlinear systems course taught > byHsiao-Dong Chiang. Really beautiful stuff. > carlos. Thanks! Looks like a really interesting read. Will
Altair clone follow-up
for those involved in the recent altair clone discussion, there's now one up on EPAY: 283958927640 (Not mine and I know nothing about it...) Steve
Re: chaos and the LGP-30
Will Cooke via cctalk wrote: On July 27, 2020 at 7:33 AM Will Cooke via cctalk wrote: On July 27, 2020 at 6:44 AM Bill Degnan via cctalk wrote:> Does the code listing exist on the web?Bill>I'm not aware of the code being available anywhere, but I haven't really looked. I did find one paper by Lorenz where he describes his weather forecasting simulations. I can find it again and send a link if anyone wants. Here is the link to the paper. "the Nature and Theory of the General Circulation of the Atmosphere" It's 10 MB and 180+ pages. http://users.uoa.gr/~pjioannou/historical/Lorenz-1967.pdf This is more like a research monograph that was published later. The original paper is Edward N. Lorenz, "Deterministic Nonperiodic Flow", Journal of The Atmospheric Sciences, Vol. 20, March 1963, pp. 130-141. It is at multiple locations in the web. One source is: http://www.astro.puc.cl/~rparra/tools/PAPERS/lorenz1962.pdf At Cornell I took John Guckenheimer's and Steve Strogatz's courses, in addition to the more EE-focused nonlinear systems course taught by Hsiao-Dong Chiang. Really beautiful stuff. carlos.
Re: (Virtual) VCF West is this weekend - tune in!
There is almost enough to split to two days. The original schedule showed 2 days so it is just the single packed day? Dwight From: cctalk on behalf of Michael Brutman via cctalk Sent: Sunday, July 26, 2020 5:52 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: (Virtual) VCF West is this weekend - tune in! Join us on August first for a virtual VCF event! We can't safely meet in person so we are going to do what we can online. The good news is that you can tune-in via YouTube and ask questions of the presenters via email, enabling anybody in the world with a modest Internet connection to participate. The event schedule can be found at http://vcfed.org/wp/vcf-west-event-schedule/ . It will be a long day so tune in for what you can, and then find the rest available on YouTube afterwards. -Mike
Re: AlphaServer 2100s available
RS and I were once transporting some stuff including an RP07 from DE to MD in an open trailer. I was behind him and saw the lid on the RP07 come up and off the drive and land on the road intact. Stopped quickly, backed up, got out of car just in time to watch an 18 wheeler hit it. *CRUNCH*. No more cool plastic lid. Drat. I really need to find that RP07 and get it running again. CZ On 7/27/2020 3:05 PM, Norman Jaffe via cctalk wrote: Not DEC-related, but I once had an IBM 1800 shipped from where we'd purchased it to a storage locker in a different city, where I lived. All was fine until it was unloaded, and the wheels sank into the pavement. [That summer was a bit hotter than normal...] From: "cctalk" To: "Adrian Graham" , "cctalk" Sent: Monday, July 27, 2020 9:56:56 AM Subject: Re: AlphaServer 2100s available On Jul 27, 2020, at 12:38 PM, Adrian Graham via cctalk wrote: ... That reminds me of the time I was transporting a Dodge box (Alpha 4100) between customer sites in a London borough. There were 3 machines, a pair of 4100s and a 2100. 3 of us got the 2100 and a 4100 into the van we had for this task but the 3rd machine wouldn’t fit. No problem, I have a big estate car (station wagon) so could put it in the back of that. I strapped it in with occy straps (the elasticated type) and put the brakes on the front wheels but the thing was so heavy that when the car moved forwards the machine didn’t and burst through the back window. A small girl out on the street said ‘look Mum, that man’s broken his window!’ Those straps are nice for holding packages weighing up to maybe 10 pounds or so. Something non-stretchy, like cargo webbing ratchet straps, well-tied ropes, or in extreme cases chains, are for heavy stuff. I had some fun years ago moving a lathe, in pieces the heaviest of which was around 800 pounds. That's a quick course in how to secure stuff well. Your story reminds me of the -- perhaps apocryphal -- story of the RP04 (RP03?) that was being air-freighted out of Boston airport. It wasn't correctly tied down, so when the takeoff roll started, it stayed put. Same sort of consequence as yours except that it left out the back of the airplane, through the fuselage, bouncing off the runway. The story says that it was taken back to Maynard, uncrated, set up with a couple of bricks underneath one of the corners that was pushed in 6 inches or so, and tested. It still worked. I guess DEC built sturdy, and from your experience they kept doing that for a long time. paul
Re: AlphaServer 2100s available
Not DEC-related, but I once had an IBM 1800 shipped from where we'd purchased it to a storage locker in a different city, where I lived. All was fine until it was unloaded, and the wheels sank into the pavement. [That summer was a bit hotter than normal...] From: "cctalk" To: "Adrian Graham" , "cctalk" Sent: Monday, July 27, 2020 9:56:56 AM Subject: Re: AlphaServer 2100s available > On Jul 27, 2020, at 12:38 PM, Adrian Graham via cctalk > wrote: > > ... > > That reminds me of the time I was transporting a Dodge box (Alpha 4100) > between customer sites in a London borough. There were 3 machines, a pair of > 4100s and a 2100. 3 of us got the 2100 and a 4100 into the van we had for > this task but the 3rd machine wouldn’t fit. No problem, I have a big estate > car (station wagon) so could put it in the back of that. > > I strapped it in with occy straps (the elasticated type) and put the brakes > on the front wheels but the thing was so heavy that when the car moved > forwards the machine didn’t and burst through the back window. A small girl > out on the street said ‘look Mum, that man’s broken his window!’ Those straps are nice for holding packages weighing up to maybe 10 pounds or so. Something non-stretchy, like cargo webbing ratchet straps, well-tied ropes, or in extreme cases chains, are for heavy stuff. I had some fun years ago moving a lathe, in pieces the heaviest of which was around 800 pounds. That's a quick course in how to secure stuff well. Your story reminds me of the -- perhaps apocryphal -- story of the RP04 (RP03?) that was being air-freighted out of Boston airport. It wasn't correctly tied down, so when the takeoff roll started, it stayed put. Same sort of consequence as yours except that it left out the back of the airplane, through the fuselage, bouncing off the runway. The story says that it was taken back to Maynard, uncrated, set up with a couple of bricks underneath one of the corners that was pushed in 6 inches or so, and tested. It still worked. I guess DEC built sturdy, and from your experience they kept doing that for a long time. paul
Re: AlphaServer 2100s available
> On Jul 27, 2020, at 12:38 PM, Adrian Graham via cctalk > wrote: > > ... > > That reminds me of the time I was transporting a Dodge box (Alpha 4100) > between customer sites in a London borough. There were 3 machines, a pair of > 4100s and a 2100. 3 of us got the 2100 and a 4100 into the van we had for > this task but the 3rd machine wouldn’t fit. No problem, I have a big estate > car (station wagon) so could put it in the back of that. > > I strapped it in with occy straps (the elasticated type) and put the brakes > on the front wheels but the thing was so heavy that when the car moved > forwards the machine didn’t and burst through the back window. A small girl > out on the street said ‘look Mum, that man’s broken his window!’ Those straps are nice for holding packages weighing up to maybe 10 pounds or so. Something non-stretchy, like cargo webbing ratchet straps, well-tied ropes, or in extreme cases chains, are for heavy stuff. I had some fun years ago moving a lathe, in pieces the heaviest of which was around 800 pounds. That's a quick course in how to secure stuff well. Your story reminds me of the -- perhaps apocryphal -- story of the RP04 (RP03?) that was being air-freighted out of Boston airport. It wasn't correctly tied down, so when the takeoff roll started, it stayed put. Same sort of consequence as yours except that it left out the back of the airplane, through the fuselage, bouncing off the runway. The story says that it was taken back to Maynard, uncrated, set up with a couple of bricks underneath one of the corners that was pushed in 6 inches or so, and tested. It still worked. I guess DEC built sturdy, and from your experience they kept doing that for a long time. paul
Re: AlphaServer 2100s available
> On 27 Jul 2020, at 17:06, Michael-John Turner via cctalk > wrote: > > On Tue, Jul 21, 2020 at 08:58:22PM +0100, Antonio Carlini via cctalk wrote: >> I can't find the weight in any of my references right now but they are very >> heavy. Three people can move them up a slight slope with some effort but you >> would not successfully lift it into a car (assuming that it would fit). I'm >> planning to dismantle them to move them (i.e. remove PSU/PSUs etc. until >> they are light enough to move). A tail-lift would probably be the sane way >> to go (and is, indeed, how they got to their current location. > > It was probably youthful stupidity, but I transported an AlphaServer 2100 in > my VW Golf 4 back in the day. I also lifted it out myself (luckily it was on > castors so just needed to make it out of the car). Sadly the machine later > died but I passed it on to a fellow Alpha-owner who stripped it for parts. > > Glad you managed to find homes for all three of them. > > Cheers, MJ > -- > Michael-John Turner * m...@mjturner.net * http://mjturner.net/ That reminds me of the time I was transporting a Dodge box (Alpha 4100) between customer sites in a London borough. There were 3 machines, a pair of 4100s and a 2100. 3 of us got the 2100 and a 4100 into the van we had for this task but the 3rd machine wouldn’t fit. No problem, I have a big estate car (station wagon) so could put it in the back of that. I strapped it in with occy straps (the elasticated type) and put the brakes on the front wheels but the thing was so heavy that when the car moved forwards the machine didn’t and burst through the back window. A small girl out on the street said ‘look Mum, that man’s broken his window!’ Fun times. At the other end we got out the Henry Hoover to suck up the glass and switched on, machine worked fine and didn’t hiccup until it was decommissioned a few years later. -- Adrian Graham Owner of Binary Dinosaurs, the UK's biggest private home computer collection? t: @binarydinosaursf: facebook.com/binarydinosaurs w: www.binarydinosaurs.co.uk
Re: AlphaServer 2100s available
On Tue, Jul 21, 2020 at 08:58:22PM +0100, Antonio Carlini via cctalk wrote: I can't find the weight in any of my references right now but they are very heavy. Three people can move them up a slight slope with some effort but you would not successfully lift it into a car (assuming that it would fit). I'm planning to dismantle them to move them (i.e. remove PSU/PSUs etc. until they are light enough to move). A tail-lift would probably be the sane way to go (and is, indeed, how they got to their current location. It was probably youthful stupidity, but I transported an AlphaServer 2100 in my VW Golf 4 back in the day. I also lifted it out myself (luckily it was on castors so just needed to make it out of the car). Sadly the machine later died but I passed it on to a fellow Alpha-owner who stripped it for parts. Glad you managed to find homes for all three of them. Cheers, MJ -- Michael-John Turner * m...@mjturner.net * http://mjturner.net/
Re: chaos and the LGP-30
> On July 27, 2020 at 7:33 AM Will Cooke via cctalk > wrote: > > > On July 27, 2020 at 6:44 AM Bill Degnan via cctalk > > wrote:> Does the code listing exist on the web?Bill>I'm not aware of the > > code being available anywhere, but I haven't really looked. I did find one > > paper by Lorenz where he describes his weather forecasting simulations. I > > can find it again and send a link if anyone wants. Here is the link to the paper. "the Nature and Theory of the General Circulation of the Atmosphere" It's 10 MB and 180+ pages. http://users.uoa.gr/~pjioannou/historical/Lorenz-1967.pdf
Re: chaos and the LGP-30
> On July 27, 2020 at 6:44 AM Bill Degnan via cctalk > wrote: > Does the code listing exist on the web?Bill > > I'm not aware of the code being available anywhere, but I haven't really looked. I did find one paper by Lorenz where he describes his weather forecasting simulations. I can find it again and send a link if anyone wants. But on the broader spectrum of chaos theory perhaps the most notable introduction is James Gleik's book "Chaos." Here is a link to it on archive.org https://archive.org/details/chaos-james-gleick Will
Re: chaos and the LGP-30
On Sun, Jul 26, 2020, 8:44 PM Jecel Assumpcao Jr via cctalk < cctalk@classiccmp.org> wrote: > Jay Jaeger wrote on Sun, 26 Jul 2020 19:24:24 -0500 > > So, either he mis-entered something, or possibly the result of a > > different state of a random number generator somewhere? > > He dumped the full state of the simulation to paper with six digits > after the decimal point even though the internal calculations used eight > digits (I don't remember the actual precisions involved). So when he > restarted the simulation from the middle he introduced errors of less > than 1 per million and fully expected the results to be the same for the > days he had already simulated so he could continue a little further. But > he was shocked that the simulation went in a different direction and the > results were totally different after only a few days. > > This is an absurd sensitivity to initial conditions that had never been > noticed in any system before. He compared it to whether a butterfly > flapped its wings or not in the middle of the Amazon making a difference > on there being a nice day or a huge storm on the other side of the world > a week later. This is the infamous "butterfly effect". > > All this came after eliminating all kinds of possible errors, of course. > The first thing we thought back then when something like this happened > was not "I found a new theory" but "the hardware is probably flaky or > there is a compiler bug". > > - Jecel > Does the code listing exist on the web? Bill >
