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Posts by John Vickers

1) Message boards : Number crunching : Small WUs is doing it again! (Message 29181)
Posted 10 Aug 2009 by John Vickers
Post:
Hello again,

The server should be running nicer now (let me know if it isn't), we went from having 4 runs [2.5deg 2s (2): 2.5deg 3s (2)] to 8 [2.5deg 3s (4): 5deg 2s (2): 5deg 3s (2)]. So there are WUs in total, more 3 stream runs, and more 5 degree stripes.

On a thread-related note-- yes, we do go out of the way to make you guys happy with the server speed. But I think this is part of our relationship-- we keep you happy by giving you work and credits, you keep us happy by providing the computing power we need. If keeping your boxes busy is the price to keep you crunching for us; well, that's a small price for 430 TFlops :)

Cheers,
John Vickers
2) Message boards : Number crunching : Gee guys, what's happening? (Message 29168)
Posted 10 Aug 2009 by John Vickers
Post:
Hello MW@Home,

Borandi is correct, for the past 2 weeks we've been running 5 degree stripes and since Saturday we've been running 2.5 degree stripes. This translates to half as many nu steps and thus half as large WUs.

John Vickers

3) Message boards : Number crunching : Test wu's (Message 29167)
Posted 10 Aug 2009 by John Vickers
Post:
Hello,

The last two weeks were spent running convergence tests by Travis. This didn't contribute to the Astrophysics portion of this project, but the data was used for a Computer Science paper we submitted last Friday.

John Vickers
4) Message boards : Number crunching : Small WUs is doing it again! (Message 29166)
Posted 10 Aug 2009 by John Vickers
Post:
Hello MW@Home,

I took over the BOINC server this past weekend (Saturday is when these "small" WUS should have started showing up).

For the prior 2-3 weeks Travis had been running convergence tests on 5 degree wide stripes-- I am however working on 2.5 degree wide stripes which translates to half as many nu steps and thus half as large WUs. These WUs should be running just as fast as they usually ran before I introduced the 5 degree stripe size about 2 months ago-- is this so?

I can put some more 5 degree tests up later today when I get a chance.

Thanks for your patience,
John Vickers
5) Message boards : MilkyWay@home Science : What in the world does this project do? (Message 29163)
Posted 10 Aug 2009 by John Vickers
Post:
Hello,

There is a similar explanation of the science side of this project that I wrote stickied at the top of these (science) forums-- it has pictures and animations and whatnot. Here is a direct link,

http://milkyway.cs.rpi.edu/milkyway/forum_thread.php?id=902

If you have any more questions, just ask.

John Vickers
6) Message boards : MilkyWay@home Science : 2012 (Message 26246)
Posted 22 Jun 2009 by John Vickers
Post:
Hello MW@Home and ztmike:



lol what?

This 2012 thing has been around ALOT longer than the new upcoming movie "2012" I think you better get your facts straight, before criticizing something.

Try Googling "Nibiru"
To answer the OP's question...nobody here can say for CERTAIN what the future brings, but I'm sure if there's a planet heading towards Earth, NASA and the governments already know about it..but are keeping it hush hush due to panic.


I'm pretty sure that my facts are straight :P, that website he linked stating he got information from it is actually made by Sony. The scientists and "facts" featured therein are entirely fictitious and created to bring publicity to the movie. Check the bottom of the webpage for publication info :)

I can also Google "The Montauk Project" or "The Philadelphia Project" or "The Jersey Devil" or "HAARP" or "Chemtrail Theory" and get a lot of very nice information. That doesn't mean that I believe every disturbing thing I see :)

Cheers,
John Vickers
7) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 25174)
Posted 12 Jun 2009 by John Vickers
Post:
Borandi,

What you've said about combining 2 wedges to make bigger wedges is a good idea, and one I have recently been playing with (all the sgr_*F_ runs, the F stands for Fat, haha). I guess the primary issue is that we don't want the total volume to have a curved section of stream in it, since the program removes straight cylinders. The more nu space we use, the more noticeable the curvature becomes.

To get a better fit of the transforms between stripes I'm thinking that we may recombine all the data and then shift the stripes 1.25 degrees so we end up with stripes in between the old stripes (for example we could combine the top half of stripe 11 with the bottom half of stripe 12 and end up with a stripe 11.5-- this could double our data points).

I honestly have no clue what processor Nate started his work on, I wasn't even at RPI then haha.

SDSS data as I recieved it was a 1.06 gig, 14 column file with the columns representing things such as coordinates, color, distance, etc. this 1.06 gigs represents only stars classified as F-turnoff, I think all SDSS data is around 3.3 TB. You can get a look at their data through the SDSS website http://das.sdss.org/www/html/ -- I'm unsure if it's available for download though. I know Dr. Heidi Newberg worked closely with the people at SDSS and she may have gotten the data from her colleagues.

Could you please rephrase that bit about sgr data? When you say sgr data I'm thinking you are referring to the new sgr coordinate system-- in which case the data is the same, all points were just passed through a rotation matrix to get them in a new orientation.

And when you say that data past the galactic center is liable to systemic error, I'm thinking that most of the data we are studying is far away from the galactic plane and thus not particularly affected by the center-- we avoid the area of the sky that you need to peer through the galactic center to see.

Cheers,
John Vickers
8) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 25073)
Posted 11 Jun 2009 by John Vickers
Post:
Hey MW@Home,

I'm actually not very sure on the math behind the fitness calculation-- and things like "how close" are pretty arbitrary. I've asked Matt to try and help me answer this. The specifics behind that calculation can also be found in Nate's Thesis.

The algorithm we work with is a maximum likelihood calculator. So the results with higher (less negative) fitnesses are better. So an answer of -2.5 is better than an answer of -3.0 and an answer of -0.0 is an absolutely perfect answer. On some of my stripes -2.6 is the highest I can get, while others can get all the way up to -2.4-- it's really variable

It is difficult if not impossible to compare these fitnesses between stripes since the number is based on a number of factors such as star count and stripe volume which vary from stripe to stripe. Similarly "how close" we need to be to get accepted answers differs from stripe to stripe.

A good guideline is if our errors on a parameter are a magnitude less than the found value. For example if we calculate a distance of 29 kpc, we want our error to be on the order of 1 kpc or less-- our errors are based on a Hessian calculation which accommodates all the variables.

The uniform density of stars is perhaps a poor use of words on my part-- since that density is actually modeled by the parameters q and r0. As you get farther and farther away from the middle of the Milky Way, it gets less and less stellarly dense (how far and how quickly are predicted by q and r0). So basically the program will remove the stream and see how uniformly the field will fit a q and r0 model.

Imagine the program pulls a stream out but its just a little off of the real stream so there is still a crescent shape of overdensity left. The program then goes through the stars, checking that the density is correct at a given position based on q and r0. When it runs into parts of the sky where it is too dense (like the crescent shape) or too sparse, it will lower the likelihood.

So, in general you want to take your highest likelihood of all your runs and call that the answer. Unfortunately we are running into an issue where the mathematic best fit is physically impossible (for example a stream could fit well mathematically in a way that wouldn't appear in the next stripe-- but we know that the stream still exists in the next stripe so this answer cannot be!), so we need to look at "families" of results and pick the best from the family of reasonable results.

So if the errors are small, and all the findings fit with each other when we look at the big picture, we can assume that we have a proper answer. The fitness is basically just a tool for finding what could be the best answers-- as sometimes it can lead you to an answer that is impossible.

John Vickers
9) Message boards : Number crunching : ps_sgr_*F_2s_1 (Message 25068)
Posted 11 Jun 2009 by John Vickers
Post:
Yes,

Thicker means that I've doubled the nu range (5 degrees instead of 2.5 degrees). I dont think this affects credit gain as that is based on the number of steps in each integral if I remember correctly.

That is a good point though-- I should have doubled the integral step size for that parameter and that would logically give you double credits.

I'll try to do that next time :P

Cheers,
John Vickers
10) Message boards : Number crunching : ps_sgr_*F_2s_1 (Message 25058)
Posted 11 Jun 2009 by John Vickers
Post:
Hello MW@Home,

Please let me know if these runs are causing you errors. They are twice as thick as other wedges.

Thanks,
John Vickers
11) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 24986)
Posted 11 Jun 2009 by John Vickers
Post:
Reserved
12) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 24985)
Posted 11 Jun 2009 by John Vickers
Post:
Reserved
13) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 24984)
Posted 11 Jun 2009 by John Vickers
Post:
Reserved
14) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 24983)
Posted 11 Jun 2009 by John Vickers
Post:
June 17 - Latest results.

These are the best results from the past week-- this week we ran mostly "F" runs (named something like ps_sgr_*F_*_*). Basically these runs are of 5 degree wedges instead of 2.5 degree wedges.

The images have the total field in the top right, the stream in the bottom right, and the background in the top left.

SGR stripe 12:


SGR stripe 18:


SGR stripe 22:


SGR stripe 26:


SGR stripe 30:


Combined vectors for this week:
15) Message boards : MilkyWay@home Science : MilkyWay@Home Progress Report (Old) (Message 24982)
Posted 11 Jun 2009 by John Vickers
Post:
16) Message boards : Number crunching : Compute Errors (Message 24912)
Posted 11 Jun 2009 by John Vickers
Post:
KWSN,

Are you using the code recently released by Cluster Physik ( http://milkyway.cs.rpi.edu/milkyway/forum_thread.php?id=886#24282 ) that included a fix for 3 stream runs on ATI GPUs? This is most likely the issue if its the *_3s_* runs crashing and only on GPU.

Thanks,
John Vickers
17) Message boards : Number crunching : ps_sgr_235_3s errors remain (Message 24699)
Posted 9 Jun 2009 by John Vickers
Post:
Monkee,

Do you have Cluster Physik's new ATI application .19f ?

http://milkyway.cs.rpi.edu/milkyway/forum_thread.php?id=886#24282
18) Message boards : Number crunching : ps_sgr_235_3s errors remain (Message 24695)
Posted 9 Jun 2009 by John Vickers
Post:
Is it also erroring on ps_sgr_210_3s_5 or ps_sgr_235_3s_5?

Thanks,
John Vickers
19) Message boards : Number crunching : ps_sgr_235_3s errors remain (Message 24670)
Posted 9 Jun 2009 by John Vickers
Post:
Thank you for bringing this to my attention, it's my error (first week on BOINC, please be patient haha). Can you tell me if there is a problem with ps_sgr_235_3s_5?

Cheers,
John Vickers
20) Message boards : MilkyWay@home Science : 2012 (Message 24582)
Posted 8 Jun 2009 by John Vickers
Post:
As an update.

This is a viral marketing scheme for the movie 2012.

Similar to the marketing done by the movie Cloverfield where they claimed that ships were disappearing in Asian waters.

Check out the footer on the IHC website.


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