Users February 2012

users@lists.einsteintoolkit.org

20 participants
31 discussions

Einstein Toolkit Meeting Reminder
by Frank Loeffler 14 May '15

14 May '15

Hi Please consider joining the weekly Einstein Toolkit phone call at 10 am US central time on Mondays. As usual, you can find instructions how to join on the following web site: http://einsteintoolkit.org/community/support/ I short: the number is (+1) 225-578-4942 or (+1) 866-573-0359 and the conference id is 118682#. My agenda contains: - Fall workshop - PLEASE let us know if you come [1]! - Hotel booking - Release planning - release date: Mon Oct 24 2011 - freeze date: Mon Sep 26 - the day of the call! - branch name: ET_2011_10 - List of release-concerning bugs [2] - ET paper: proposed "freeze" by Oct 3rd (Mon after this call) As always: feel free to add to this list. Frank Loeffler [1] https://docs.einsteintoolkit.org/et-docs/ET_Workshop_Fall_2011#Fall_Einstei… [2] https://trac.einsteintoolkit.org/query?status=!closed&milestone=ET_2011_11&…

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Simulation domain volume and reduction weight sum differ
by Jakob Hansen 25 Sep '12

25 Sep '12

Hi, Using mercurial, I get this warning during simulations : INFO (CarpetReduce): Simulation domain volume: 170368000 INFO (CarpetReduce): Reduction weight sum: 170367999.880642 WARNING level 1 in thorn CarpetReduce processor 0 host tachyon2974 (line 120 of /home01/r632kgw/jakob/CactusP/arrangements/Carpet/CarpetReduce/src/mask_test.c): -> Simulation domain volume and reduction weight sum differ Simulations seem to run okay though. What is causing this warning and is it serious or can I just ignore it? Cheers, Jakob

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support_old_CalcTmunu_mechanism
by Frank Loeffler 23 Sep '12

23 Sep '12

Hi, Are there objections to change the default of TmunuBase::support_old_CalcTmunu_mechanism from "yes" to "no"? Frank

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Propose thorns for inclusion in the EinsteinToolkit
by Barry Wardell 26 Apr '12

26 Apr '12

Hi, Recently Ian Hinder and I have created an arrangement of thorns called EinsteinExact which provide some exact solutions for use in Cactus. The scope of these thorns is similar to that of the Exact thorn but with some notable improvements: * The extrinsic curvature is computed symbolically rather than using finite differencing so it should be accurate to within roundoff. This means that EinsteinExact is more exact than Exact. * The solutions used in EinsteinExact come from a database of metrics which have been correctness-tested, e.g., by checking symbolically that they are a solution of the Einstein equation. * EinsteinExact is written in Mathematica and uses Kranc, so the raw source is very small (~250 lines) and easy to understand. * Adding a spacetime is as simple as typing the components of the metric into Mathematica. So far, the spacetimes included are Minkowski, Kerr-Schild, gauge wave and shifted gauge wave, but the list can easily be extended in the future. There is also support for arbitrary rotations, using the same conventions as the Exact thorn uses. We have not yet included the other transformations supported by Exact, but they shouldn't be difficult to add. We have checked that for these spacetimes the Exact solutions converge to the EinsteinExact solutions at the correct finite differencing order used by Exact. We would like to propose the EinsteinExact arrangement for inclusion in the EinsteinToolkit. If you would like to try it out, you can get it using: git clone --recursive git://github.com/barrywardell/EinsteinExact Any comments or suggestions are welcome. Regards, Barry

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Can't evolve Minkowski with RK4 integrator?
by Erik Schnetter 03 Apr '12

03 Apr '12

I've just encountered a strange problem: I can't evolve Minkowski with MoL's RK4 integrator. Small errors in K grow from floating-point round-off, and the simulation quickly goes bad. The error grows slowly (but measurably) in unigrid, but much faster with mesh refinement. For example, with unigrid the lapse grows by about 10^-15 every ten time steps or so; with mesh refinement, the simulation dies after a few ten time steps. However, things are fine with other time integrators, in particular with the generic RK1 and RK4 integrators. I've looked at other things as well, e.g. the CFL factor, the McLachlan implementation, the gauge parameters, dissipation, but could not find anything else that made a difference. Is there something bad about the RK4 integrator? Is it intrinsically unstable, more so than other RK schemes? Or did it break in some of the recent changes? -erik -- Erik Schnetter <schnetter(a)cct.lsu.edu> http://www.perimeterinstitute.ca/personal/eschnetter/

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using PBS -V on kraken
by Roland Haas 09 Mar '12

09 Mar '12

Hello all, I'd like to use PBS's -V switch (propagates environment settings to the qsub script) on Kraken (through simfactory2). Simfactory currently does not use this swich on Kraken. In fact NICS recommends against using -V (http://www.nics.tennessee.edu/computing-resources/kraken/running-jobs#Batch…): --8<-- Note: Please do not use the PBS -V option. This can propagate large numbers of environment variable settings from the submitting shell into a job which may cause problems for the batch environment. Instead of using PBS -V, please pass only necessary environment variables using -v <comma_separated_list_of_ needed_envars>. You can also include module load statements in the job script. --8<-- TACC on the other hand actually requires you to have the flag present (for the modules I presume). Did anyone every actually experience any issues with -V on Kraken? Mostly I would like to use the flag so that Cactus' $ENV{'...'} mechanism works without me having to modify the run/submission scripts by hand. Is there maybe a simfactory option to define extra environment variables (I only need one but would rather not hard-code it into the submission script and instead could add it to the submit call)? Yours, Roland -- My email is as private as my paper mail. I therefore support encrypting and signing email messages. Get my PGP key from http://keys.gnupg.net.

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Einstein Toolkit Meeting
by Frank Loeffler 05 Mar '12

05 Mar '12

Hi Please consider joining the weekly Einstein Toolkit phone call at 10 am US central time on Mondays. As usual, you can find instructions how to join on the following web site: http://einsteintoolkit.org/community/support/ I short: the number is (+1) 225-578-4942 or (+1) 866-573-0359 and the conference id is 118682#. This week we will start with questions/issues/problems that might have come up recently, and will after that switch to the organization of the Einstein Toolkit workshop in Atlanta [1]; so that people not interested in the glory details can drop out at this point. Frank Loeffler [1] https://docs.einsteintoolkit.org/et-docs/ET_Workshop_Spring_2012

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changing CarpetRegrid2 parameters for ETK Maxwell + mercurial Carpet?
by Kelly, Bernard J. (GSFC-660.0)[UNIVERSITY OF MARYLAND BALTIMORE COUNTY] 01 Mar '12

01 Mar '12

Hi all. At Erik's suggestion (off-list), I resolved some checkpoint recovery issues by moving from "Curie" to the new ETK release. However, my old grid specifications seem no longer to work. The parameters are for a 2:1 mass-ratio BHB evolution. I've used three "centres" -- one each for the punctures, and one centred at the origin. Below is what I used to have in CarpetRegrid2, which worked with the last "Curie" release of ETK (the full grid is [-2048,2048] in size). ------------------------------------------------------------------- # Parameters of thorn CarpetRegrid2 (implementing CarpetRegrid2) CarpetRegrid2::freeze_unaligned_levels = "yes" CarpetRegrid2::num_centres = 3 CarpetRegrid2::num_levels_1 = 12 CarpetRegrid2::position_x_1 = -3.3333333333333333333 CarpetRegrid2::movement_threshold_1 = 0.10 CarpetRegrid2::radius_1[5] = 40 CarpetRegrid2::radius_1[6] = 20 CarpetRegrid2::radius_1[7] = 10 CarpetRegrid2::radius_1[8] = 5 CarpetRegrid2::radius_1[9] = 2.5 CarpetRegrid2::radius_1[10] = 1.25 CarpetRegrid2::radius_1[11] = 0.625 CarpetRegrid2::num_levels_2 = 13 CarpetRegrid2::position_x_2 = 6.6666666666666666667 CarpetRegrid2::movement_threshold_2 = 0.05 CarpetRegrid2::radius_2[5] = 40 CarpetRegrid2::radius_2[6] = 20 CarpetRegrid2::radius_2[7] = 10 CarpetRegrid2::radius_2[8] = 5 CarpetRegrid2::radius_2[9] = 2.5 CarpetRegrid2::radius_2[10] = 1.25 CarpetRegrid2::radius_2[11] = 0.625 CarpetRegrid2::radius_2[12] = 0.3125 CarpetRegrid2::num_levels_3 = 6 CarpetRegrid2::radius_3[1] = 1024 CarpetRegrid2::radius_3[2] = 512 CarpetRegrid2::radius_3[3] = 256 CarpetRegrid2::radius_3[4] = 160 CarpetRegrid2::radius_3[5] = 96 CarpetRegrid2::regrid_every = 60 CarpetRegrid2::verbose = "yes" ------------------------------------------------------------------- This doesn't work now, however. Current ETK complains that some entries in radius_1 and radius_2 are unspecified, and it sets them to zero with catastrophic results. To resolve this, I am now explicitly setting the missing levels: CarpetRegrid2::radius_1[1] = 1024 CarpetRegrid2::radius_1[2] = 512 CarpetRegrid2::radius_1[3] = 256 CarpetRegrid2::radius_1[4] = 160 CarpetRegrid2::radius_2[1] = 1024 CarpetRegrid2::radius_2[2] = 512 CarpetRegrid2::radius_2[3] = 256 CarpetRegrid2::radius_2[4] = 160 This runs, but complains every time step about mismatched "simulated domain volume" and "reduction weight sum": ---------------------------------------------------------------------------------- INFO (CarpetReduce): Simulation domain volume: 442368 INFO (CarpetReduce): Reduction weight sum: 442367.999999072 WARNING level 1 in thorn CarpetReduce processor 0 host r186i2n12.p4.nas.nasa.gov (line 120 of /home1/bjkelly1/CODES/Cactus/configs/hahndol/build/CarpetReduce/mask_test.c): -> Simulation domain volume and reduction weight sum differ ---------------------------------------------------------------------------------- After a short evolution time (7.25 M, or more than 1700 time steps), the run crashes. First there are several messages of the form: ---------------------------------------------------------------------------------- INFO (CarpetReduce): Simulation domain volume: 442368 INFO (CarpetReduce): Reduction weight sum: 442367.999991311 INFO (CarpetRegrid2): Centre 1 is at position [-3.29831,-0.331478,7.81462e-15] with 12 levels INFO (CarpetRegrid2): Centre 2 is at position [6.58787,0.867484,8.98107e-15] with 13 levels INFO (CarpetRegrid2): Centre 3 is not active INFO (CarpetRegrid2): Regridding INFO (CarpetRegrid2): Regridding levels 10 and up WARNING level 1 in thorn CarpetLib processor 58 host r186i3n7.p4.nas.nasa.gov (line 182 of /home1/bjkelly1/CODES/Cactus/configs/hahndol/build/CarpetLib/dh.cc): [...] -> /home1/bjkelly1/CODES/Cactus/configs/hahndol/build/CarpetLib/dh.cc:948: [ml=0 rl=10 c=59] The following grid structure consistency check failed: Synchronisation and boundary prolongation: All points must have been received needrecv.empty() [...] WARNING level 0 in thorn CarpetLib processor 94 host r186i3n12.p4.nas.nasa.gov 12676 (line 1973 of /home1/bjkelly1/CODES/Cactus/configs/hahndol/build/CarpetLib/dh.cc): 12677 -> The grid structure is inconsistent. It is impossible to continue. -------------------------------------- I'm attaching my current parameter file in full. I'm reluctant to post the entire STDOUT/STDERR, since it's around a MB in size. Any ideas would be appreciated. I would turn to the copious documentation on CarpetRegrid2, but as noted before, there is none. Thanks, Bernard ----------------------------------------------------------------------------- Bernard Kelly -- CRESST Research Associate, NASA/GSFC Phone: +1 (301) 286-7243 E-Mail: bernard.j.kelly(a)nasa.gov<mailto:bernard.j.kelly@nasa.gov> Web: http://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&iphone… -----------------------------------------------------------------------------

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Question about SummationByParts
by Heeil Kim 27 Feb '12

27 Feb '12

Hi all, I'd like to know the effect of SummationByParts when it is activated. If it's activated, does it touch by default some finite-differencing scheme? For example, In qc0-mclachlan.par, SummationByParts is activated with 4th order, does it mean all 1st derivatives are replaced with SBP? Or in SBP in qc0 does nothing because it's never been inherited by other thorns? Cheers, Hee Il

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Meeting Minutes
by Roland Haas 27 Feb '12

27 Feb '12

Present were: Peter, Frank, Christian, Tanja, Roland, Josh, Ian, Bruno * no new about elliptic solver, Erik might now details Spring Workshop in Atlanta: * Tanja put a direct link to book a room in the reserved block onto the wiki http://hamptoninn.hilton.com/en/hp/groups/personalized/A/ATLGTHX-ETW-201204… * will reserve second block at Hotel Midtown (~80 plus taxes) which is less convenient (about 15min walk to student center, MARTA to APS conference) * Dennis will prepare updated Cactus virtual machine images. Please try them out and report if anything is missing. * please attach your name to sessions within the schedule https://docs.einsteintoolkit.org/et-docs/Schedule_Proposal by Wednesday * Workshop Flyer updated version will be ready today or tomorrow * invited speakers (tentative, incomplete): Matt Duez, John Wise * Bruno will provide list of NR topics and add a link to the wiki, can then discuss what to cover ET paper: * have received feedback from referee Yours, Roland

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Users February 2012