Posts by Sidd
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1) Message boards : News : Nbody 1.68 release (Message 67022)
Posted 1 Feb 2018 by Sidd
I believe I found the workunit that was from.

Because I added an entirely new calculation, there were some new parameters needed for future flexibility. Therefore, if you were to use the old parameter files on the new binary it would give that error. It seems for some reason, that workunit did exactly that, the binary being used is the nbody v168 but the workunit is from the v166 runs, using the v166 parameter files. Before releasing, I took down the older runs, and so I was not expecting the work units to do this, and for that I apologize.

Fortunately, this error would occur right at the beginning, before anything began to run so it will not cause any wasted computational time. If you have any v166 runs in your queue, you can go ahead and cancel them so they do not give this error.
2) Message boards : News : Nbody 1.68 release (Message 67020)
Posted 1 Feb 2018 by Sidd
Thanks for letting me know!! I'm checking it out right now.
3) Message boards : News : Nbody 1.68 release (Message 67017)
Posted 31 Jan 2018 by Sidd
Hi All,

A new version, v1.68, of nbody has just been released. I have not yet released the mac multi-threaded version (OpenMP). I will release this at a later date.

In this release we have added a new way of constraining the width of the stream. Previously, we were using a measure of the velocity dispersion in each histogram bin. This led us to fit our parameters quite well. Unfortunately, we found that this may not be the best method in the long run. I have added a measure of the beta coordinate dispersion which, from initial findings, will be (hopefully) easier to fit our parameters with.

As always, please let me know if there are issues.

Thank you all for your continuing support,
4) Message boards : News : Validation Inconclusive Errors (Message 66946)
Posted 10 Jan 2018 by Sidd
Hi all,

Can you please list some of the workunits that are marked as inconclusive and unsent?

5) Message boards : News : Validation Inconclusive Errors (Message 66933)
Posted 6 Jan 2018 by Sidd
Hi all,

There has been some reports of validation inconclusive issues occurring with the Nbody workunits. It seems to be isolated to the nbody app. I believe this coincided with a database issue on our end. I am working on resolving the issue.

Thank you for you patience and continued support,
6) Message boards : News : Clearing the Queue (Message 66695)
Posted 18 Oct 2017 by Sidd
Hey All,

We will have to clear the workunit queue for both separation and nbody. This will cause many invalid workunits. We apologize for this, as this is the only way to clear the system for it to return to normal operation.

Thanks for your continued support,
Jake and Sidd
7) Message boards : News : nbody 1.66 release (Message 66676)
Posted 2 Oct 2017 by Sidd
Hey All,

I just released version 1.66 of Nbody. This version has a newer version of the likelihood comparison algorithm which is used when comparing our test histograms with the client-side simulations. With this update we are hoping to have much better convergence in our parameter searches.

As always, please let us know if there are any issues.
8) Message boards : News : Server Maintenance (Message 66497)
Posted 30 Jun 2017 by Sidd
Hey All,

For some reason I am not getting any return results from the Nbody app. The validator went down over the weekend and caused a huge backlog in the queue. I think this may be the issue as we have had something similar before. I am going to cancel the workunits in the queue and let it refill. If you see anything strange in the next 24 hrs with nbody workunits this is the reason.

9) Message boards : News : nbody 1.64 release for Mac (Message 66430)
Posted 11 May 2017 by Sidd
Hey All,

I just released the newest version of nbody, version 1.64, for Mac single and multi-threaded. Please let me know if there are any issues.

PLEASE NOTE: We only have one mac machine for building and testing, meaning I had to test the binaries on the same machine that I built them on. So please let me know if anything strange crashing is seen.

Thank you all for your continued support,
10) Message boards : News : New Release 1.64 (Message 66425)
Posted 9 May 2017 by Sidd
Hey All,

The new versions of our apps are not compatible with the old versions which is why they error out right away. We did some maintenance to clear the queue so that the only workunits sent out are the new ones. But there are still some that are out there already. This should clear up in a day or two.

11) Message boards : News : New Release 1.64 (Message 66410)
Posted 8 May 2017 by Sidd
Hey guys,

I just put up some runs for the new version, so let me know if there are any problems with those. As for the issues you guys have been reporting:

1. the antivirus problem I believe we have seen before. You probably have to make boinc an exception under your firewall.

2. The previous version of nbody is a bit incompatible with the new version, so there might be a few days where the old runs are finishing up. Though they should not error out, so you should still be getting credit for them.

As always, thanks,
12) Message boards : News : New Release 1.64 (Message 66347)
Posted 3 May 2017 by Sidd
Hey All,

I am about to release a new version of nbody. This version has a number of updates that expands functionality. I will make a blog post describing these updates soon.

We do not have mac binaries this time around. We are working on getting those. We also do not have 32bit support on either linux or windows.

The system I built the linux binaries on was Ubuntu 14.04 so there is the distinct possibility that they may not run on systems older than this.

I will put up some runs after releasing. Please let me know if there are any problems.
13) Message boards : Number crunching : Always immediate segfault on MilkyWay@Home N-Body Simulation v1.62 (mt) (Message 65039)
Posted 17 Aug 2016 by Sidd

Thanks for letting us know. I looked into it and it seems that this workunit ran successfully on other systems. However, on a couple of systems there was max disk usage exceeded errors. I am not sure about why that happened and am looking into it. I think perhaps this was the issue with yours but for some reason threw a different error. It might be due to the difference in operating systems, but I am not sure. I will continue looking into it.

If this continues with other workunits, please be sure to let us know,

14) Message boards : News : Nbody Release 1.62 (Message 64769)
Posted 28 Jun 2016 by Sidd

I am not entirely sure. I had a run up until last night but the server may not have been sending out new work units since it was more or less converged. But I will be putting up new runs later today or tomorrow so WU will start flowing soon.

Thanks for your patience!
15) Message boards : News : Nbody Release 1.62 (Message 64767)
Posted 28 Jun 2016 by Sidd
Hey All,

I just released a new version of nbody, v1.62. In this release we did a few things:

We realized that different platforms were giving slightly different results. This was a problem as it would throw off the search algorithm and also may cause validation issues. Turns out there were an number of reasons for this. One was that the likelihood calculation was performed using single precision on a double precision application. So we changed it to be a double precision calculation.

Also, and most prominently, we realized that the windows command prompt and unix terminal read in inputs with different precision. One would cut the value of after about the 10th decimal place. This mean the actual input parameters were slightly different! Therefore, we forced the rounding of the input parameters after the 9th decimal place. That seemed to do the trick mostly.

Finally, we realized that our building mechanism was not building linux binaries statically. When we tried with our current mechanism we ran into a can of worms known as seg faults. It was a nightmare trying to find it so we decided to temporarily switch our building mechanism. I tested them on all our computers and it seems to work. But, as always, let me know if something goes awry.

Thanks everyone for your continued support!
16) Message boards : News : Nbody Release 1.60 (Message 64571)
Posted 25 May 2016 by Sidd

The inertia runs are meant to help us optimize the optimizer. Our optimizer has a few free parameters we can tune. We are trying to tune them for our unique parameter surface so that we can have our runs converge in a reasonable amount of time.

As for some taking longer than others, that is more a sim parameter issue. The time step is dependent on the simulation parameters. Some of the inertia runs may be exploring our parameter space more than others so they encounter simulation parameters that lead to a longer/shorter run time.
17) Message boards : News : Nbody Release 1.60 (Message 64470)
Posted 14 Apr 2016 by Sidd
Hey All,

I just released a new version of Nbody, 1.60. In this version we completely changed the cost function. This is a function that is used in the histogram comparison algorithm. We discovered that the old cost function, which was supposed to allow us to retain the mass data in the normalized histograms, did not account properly for the amount of mass.

This was not a bug, but rather a change in the science behind the algorithm. We would not have rethought the algorithm without the results from MW@H.

As always, if there is any problem, let me know.

Thank you all,
18) Message boards : News : Nbody Release 1.58 (Message 64398)
Posted 21 Mar 2016 by Sidd
Hey All,

I just released a new version of nbody. This one fixes a bug that was found only after instituting the CM correction in the previous release. Let me know if there are any issues.

19) Message boards : News : Nbody Release 1.56 (Message 64364)
Posted 8 Mar 2016 by Sidd
Hey All,

I just released a new version of Nbody. This updates fixes some library issues we were having. Also, it adds a center of mass and center of momentum correction to the initialization (the added computation time is very negligible). We did this because we found that different seeds would produce a small random initial center of mass position and velocity. While it was not a large difference, we wanted it to be nonexistent.

I will be putting up some runs shortly.

As always, thank you all!
20) Message boards : News : Nbody Release 1.54 (Message 64087)
Posted 11 Nov 2015 by Sidd
Hey All,

I just released a new version of nbody, version 1.54. There are no major changes, just some minor bug fixes. There was a sampling bug in the velocity assignment which caused it to throw away more possible vels than it should. So the initialization is much faster than before. However, the results should be the same. But faster is always better!

Let me know if there is any issues with the new version/binaries.

Thank you!

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