Re: galaxy collision demo

From: Jay Billings <jayjaybillings_at_gmail.com>
Date: Wed, 23 Sep 2009 07:14:42 -0400

There are also read/write routines available in my Starscream package if you
just want to get the numbers out for format 1.

http://www.jayjaybillings.org/starscream

Sander is right; no need to reinvent the wheel!

Jay

On Wed, Sep 23, 2009 at 3:15 AM, Sander Valcke <Sander.Valcke_at_ugent.be>wrote:

>
> Just a quick note to those concerned (Dimitry also): you can find example
> routines on how to read Gadget IC files in the Analysis directory. Mind that
> this only works for snapshot format 1. This is fine for anyone not planning
> to ever add any custom IO blocks to the snapshots written by their Gadget
> code. For people expecting to add custom data to the snapshots I would
> recommend using snapshot format 2, as it's (much more) flexible. If there
> were examples to read snapshot 2 formats in Analysis I would recommend not
> using the snapshot format 1 at all :-), there is no downside to using the
> format 2.
>
> When you are anxious to see what's in your snapshots and don't want to wait
> till you've cooked up a reading program (and/or to check if reading the IC
> is done properly) there are a good number of tools available already: ifrit,
> splash, hyplot (see signature), ... try taking a look around at
> http://www.astrosim.net/code/doku.php. No need for each gadget user to
> reinvent the wheel ;-)
>
> Sander
>
> Douglas/Lesli Summerstay wrote:
>
>> We are developing a method for automatically selecting key-frames in data
>> that contain the most information about how the evolution of particle data
>> is happening, that best describe the animation (I am at the University of
>> Maryland, working with Amitabh Varshney). To do this, I need scientifically
>> interesting particle data in four dimensions. We thought this data would be
>> just what we needed (especially since there are already "keyframes" evenly
>> spaced in time that others have published on the web to compare it to), but
>> so far I haven't been successful in generating it. I can write a program in
>> C++ or Matlab to read the snapshot files, since they're described pretty
>> well in the documentation.
>> I would be very grateful if you could find a way to send me those
>> snapshots.
>>
>> Douglas
>>
>> On Mon, Sep 21, 2009 at 11:26 AM, Jay Billings <jayjaybillings_at_gmail.com<mailto:
>> jayjaybillings_at_gmail.com>> wrote:
>>
>> Douglas,
>>
>> I had compiled FFTW wrong in my case, but I don't know if this is
>> the problem with yours. You could probably track your problem down
>> quickly with a debugger or some print statements.
>>
>> I could supply you with some snapshots, but I have to ask why need
>> it? Also, do you have the capability to read to read the
>> snapshots? I don't mean for the first question to sound offensive;
>> I just need to be sure that you don't need it for a homework
>> problem or something.
>>
>> Jay
>>
>>
>> On Mon, Sep 21, 2009 at 11:06 AM, Douglas/Lesli Summerstay
>> <dsummerstay_at_gmail.com <mailto:dsummerstay_at_gmail.com>> wrote:
>>
>> Jay,
>> I imagine it may be, as you say, some kind of compilation
>> error on my part. It is running, using up CPU, but not
>> generating even the first snapshot in galaxy/ . Any idea the
>> nature of the error you had? Or suggestions on how to track it
>> down?
>> Unfortunately I need the 3D position data, not just the video.
>> Thanks again.
>>
>> Douglas
>>
>>
>> On Mon, Sep 21, 2009 at 10:51 AM, Jay Billings
>> <jayjaybillings_at_gmail.com <mailto:jayjaybillings_at_gmail.com>>
>> wrote:
>>
>> Douglas,
>>
>> You are correct that you should see a snapshot at t=0 for
>> the test problem. Did you look in the galaxy/ directory?
>> The snapshots are stored there.
>>
>> The test problem with default settings only outputs six or
>> seven snapshot files from t=0 to t=3.0. I'm a bit
>> concerned that it has taken "days" without creating any
>> snapshot files; that test problem runs in 15 minutes on my
>> quad core machine and in about an hour on my old P4. When
>> I first started working with Gadget2 I encountered a
>> similar problem to yours and it turned out to be a compile
>> error.
>>
>> If you are only interested in videos, you might check out
>> my youtube page: http://www.youtube.com/jayjaybillings .
>> These are videos of a different simulation.
>>
>> Jay
>>
>> On Mon, Sep 21, 2009 at 10:39 AM, Douglas/Lesli Summerstay
>> <dsummerstay_at_gmail.com <mailto:dsummerstay_at_gmail.com>> wrote:
>>
>> I am trying to run the galaxy collision sample and had
>> a few questions:
>> I am trying to run it on a single processor. How long
>> should I expect to wait before seeing any output
>> snapshot files? (I am using the default
>> parameter file.) I left it running for days without
>> seeing any snapshot files created. This seems odd
>> because the first snapshot is supposed to be created
>> at time 0. Any idea why no snapshot files are being
>> created? Alternately, could anyone run this simulation
>> and make the snapshot files available to me?
>> Are the pictures of colliding galaxies on the Gadget
>> site
>> (
>> http://www.mpa-garching.mpg.de/gadget/collision/index.html )
>> from this simulation?
>>
>> Thanks for your help.
>>
>> -- http://dsummerstay.googlepages.com
>>
>>
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>>
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>> --
>> http://dsummerstay.googlepages.com
>>
>
> --
> --------------------------------------------------
> | Sander Valcke |
> | Sterrenkundig Observatorium, Universiteit Gent |
> | Krijgslaan 281 S9, B-9000 Gent, Belgium |
> | phone +32-9-264-4796 | fax +32-9-264-4989 |
> | https://sourceforge.net/projects/hyplot/ |
> --------------------------------------------------
> Sometimes the best medicine is to stop taking something.
> --------------------------------------------------
>
>
>
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Received on 2009-09-23 13:14:44

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