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Meeting Minutes for 2025-09-18
by Lucas Timotheo Sanches 25 Sep '25

25 Sep '25

Present: Lucas(minutes), Peter Diener, Leo Rosa Werneck (chair), Roland Hass, Keith Dow, Beyhan # Agenda items - BBH gallery example: Peter says ran the example with the executable from back then (the Annie Jump Cannon release binary) and it works. He still needs to visualize it. - Move repos to GitHub: Currently, there's a user named CactusCodewe which we could potentially use. We would need to reach out to this person and ask them if they would be interested in releasing the name. Potential issues on the migration includes some loss of functionality like the ability to download large files. Moving issues is also an issue, but we are probably sticking to BitBucket for that. It was decided to vote on this issue again once Steve is back. # Unanswered questions on the mailing list. - "Issues Running BNS and GW150914 Example Simulations + storing BSSN variables": Roland is in contact with the person and trying to help them. - "Questions about old ET releases and bundled libraries on clusters": You can't download old releases. Too bad. No sure if old cold will compile with modern compilers. # Tickets - 2706: Zach says there are updates, but things are moving slowly. Needs more time. - 2886: Roland says this is more of a TODO than a ticket. - 2866: Just comment it out. Still waiting on a response from the reporter. - 2858: Lucas still didn't have time to look into these files. - 2882: Alejandra is still working on testing if there are performance improvements. - 2664: No updates. - 963: Improve accuracy: Peters says testings are running, to early to tell.

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Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 24 Sep '25

24 Sep '25

Hello, Please consider joining the weekly Einstein Toolkit phone call at 9:00 am US central time on Thursdays. For details on how to connect and what agenda items are to be discussed, use the link below. https://docs.einsteintoolkit.org/et-docs/Main_Page#Weekly_Users_Call --The Maintainers

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Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 22 Sep '25

22 Sep '25

Please update the Wiki with agenda items for Thursday's meeting. Thanks! https://docs.einsteintoolkit.org/et-docs/meeting_agenda --The Maintainers

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Assistant Professor - Computational Astrophysics, The University of Tennessee, Knoxville
by Mewes, Vassilios 22 Sep '25

22 Sep '25

Hi all, See the attached pdf document for an Assistant Professor in Computational Astrophysics opening at the nearby University of Tennessee in Knoxville. Please share this with any interested candidates. Best wishes, Vassili

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clarification on folders output-xxxx
by IOSIF PANAGIOTIS 18 Sep '25

18 Sep '25

Hi all, I am not sure I understand what the output-xxxx folders do under each individual simulation folder. Suppose we "create-submit" a new simulation named test. The results will appear in the output-0000 folder under the folder "home/username/simulations/test/". OK, great. Suppose now we want to re-run that simulation. And suppose we want to re-run it from scratch and not continue from a previous checkpoint (e.g. maybe we forgot to save some output we needed). The skeleton is already created, so we can just use the command submit this time. The results will appear in the output-0001 folder. Is the above understanding correct? Questions: * When we submit again the simulation for the re-run, do we have to specify the same computational resources? * I.e. is this info something already encoded in the simulation's skeleton and therefore we should keep it fixed for consistency? * Does the skeleton of the simulation also fix what quantities are saved and therefore if we forgot to save some quantity we have to create a new simulation skeleton? Additionally, from what I understand, the output-xxxx folders mainly handle different checkpoints of a larger simulation that could take weeks or months. * Does the user have to do anything to combine all the information from the checkpoints, or is this handled automatically by ETK / SimFactory? * Is there any advice on best practices regarding this scenario? Best, Panayotis ------------------- Panagiotis Iosif postdoctoral researcher Department of Physics, University of Trieste Via Alfonso Valerio 2, Trieste 34127 Italy -------------------

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Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 17 Sep '25

17 Sep '25

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Applications Open for Postdoctoral Research Positions
by Kendrick Smith 17 Sep '25

17 Sep '25

Perimeter Institute for Theoretical Physics is inviting applications for Postdoctoral Research positions. Dear Valued Colleague, Perimeter Institute for Theoretical Physics is inviting applications for the Postdoctoral Research Program (https://landing.perimeterinstitute.ca/e3t/Ctc/2I+113/cjL-604/VVCJsX700VFxF2… ) . For more information, please visit the job posting (https://landing.perimeterinstitute.ca/e3t/Ctc/2I+113/cjL-604/VVCJsX700VFxF2… ) . We hope you will share the news by: 1. Forwarding this information directly to prospective candidates who may be interested in this opportunity 2. Downloading, printing, and hanging the poster (https://landing.perimeterinstitute.ca/e3t/Ctc/2I+113/cjL-604/VVCJsX700VFxF2… ) 3. Sharing LinkedIn (https://landing.perimeterinstitute.ca/e3t/Ctc/2I+113/cjL-604/VVCJsX700VFxF2… ) and Facebook (https://landing.perimeterinstitute.ca/e3t/Ctc/2I+113/cjL-604/VVCJsX700VFxF2… ) posts with your social networks Perimeter Institute offers a dynamic, multi-disciplinary environment with maximum research freedom and opportunity to collaborate. We welcome all candidates to apply by November 1, 2025 but applications will be considered until all positions are filled. Thank you in advance for forwarding and sharing this information. Sincerely, Kendrick Smith Committee Chair Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5, Canada, 519-569-7600

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Issues Running BNS and GW150914 Example Simulations + storing BSSN variables
by Sandeep Suresh CrangaNORE 15 Sep '25

15 Sep '25

Dear EinsteinToolkit team I am currently running the Binary Neutron Star (BNS) -- (https://einsteintoolkit.org/gallery/bns/index.html) and GW150914 (https://einsteintoolkit.org/gallery/bbh/index.html) binary black hole example simulations on our workstation environment: * *Processors:* AMD EPYC 7542, 32 cores per socket, 2 threads per core (64 logical cores) * *Memory:* 2 TiB RAM * *Kernel:* Linux 5.14.0-570.37.1.el9_6.x86_64 * *OPENMPI version:* mpirun (Open MPI) 4.1.1 Both simulations use the standard example parameter files and initial data provided in the toolkit. I shall describe the problems while running these simulations as two different sections: *BNS: *On running the command ./simfactory/bin/sim create-submit bns --parfile bns.par --procs=<num_procs> --num-threads=<num_threads> --walltime=xx:xx:xx I encounter the error: WARNING level 1 from host panther process 0 in thorn ML_BSSN_Helper, file /system/user/crangano/einstein_toolkit/BNS/configs/sim/build/ML_BSSN_Helper/Parameters.c:166: -> Parameter ML_BSSN::my_boundary_condition is outdated; please update the parameter file. Do not use this parameter, and set up RHS boundary conditions as usual. cactus_sim: grille3d.C:125: Grille3d::Grille3d(int, int, int, int, int, int, int): Assertion `nr > 0' failed. Rank 0 with PID 3273101 received signal 6 For this I have attached the par file, err file, the out file (the initial data file is the one that is already there online: G2_I12vs12_D4R33T21_45km.resu.xz <https://einsteintoolkit.org/gallery/bns/G2_I12vs12_D4R33T21_45km.resu.xz>) that I am currently using. I tried to find the `nr` in the par file, but didn't find it. I am not sure if this is a MPI/num procs related problem, or is it something in the .par file that one needs to be change ? *GW150914: */Error 1 -- /Here, it is much more complicated to understand for me. This persists even after disabling |CoordinatesSymmetry::reflection_z|. Is it likely caused by coarse grid resolution relative to the number of symmetry/ghost zones. /Error 2/ -- Another error that I often encounter is File "/system/user/crangano/simulations/GW150914_28/output-0000/GW150914.rpar", line 126, in <module> sphere_outer_radius = int((outermost_detector + final_time)/(i*hr))*i*hr ZeroDivisionError: float division by zero Error: Error while executing parameter file script /system/user/crangano/simulations/GW150914_28/output-0000/GW150914.rpar Aborting Simfactory. -- I guess this occurs in the following line of the *GW150914.rpar* sphere_outer_radius=int((outermost_detector+final_time)/(i*hr))*i*hr sphere_outer_radius=int(sphere_outer_radius/hr) *hr+hr# round up to a multiple of hr So, I changed line 78 of the *GW150914.rpar as follows: * # Number of cells across finest grid radius n=int("@N@") if"@N@"[0] !="@"else28 i=max(int(n/4), 1) Is this a valid fix, or does this affect the simulations ? For this too, I attach the err, out and the par file such that you can inspect it. *Storing BSSN variables*:We would like to store the BSSN evolved *3-metric* (|γ_ij|), *lapse* (|α|), and *shift* (|β^i|) and also the corresponding coordinates (t, x^i) of these quantities at regular intervals (e.g., every 128 steps) to manage disk usage efficiently. Moreover, since AMR is used, is there any way we can keep track of the changes in resolution of the coordinates, since we also aim to do spatial derivatives via our FD stencils -- Jacobians and Hessians of these quantities. If there are ways to directly dump the Jacobians and Hessians of these quantities (by adding lines on the par file), w/o us implementing (since we are not aware of the AMR being used at different regions to implement our FD stencils), that would be very useful too. IOHDF5::out_vars = " ML_BSSN::ML_metric ML_BSSN::ML_lapse ML_BSSN::ML_shift Grid::Coordinates{out_every=1000000000 refinement_levels={0}} ML_BSSN::ML_log_confac WeylScal4::Psi4r WeylScal4::Psi4i WeylScal4::curvIr{refinement_levels={3 5}} WeylScal4::curvIi{refinement_levels={3 5}} WeylScal4::curvJr{refinement_levels={3 5}} WeylScal4::curvJi{refinement_levels={3 5}} " I would appreciate guidance on the proper way to quickly resolve these errors. Ideally, we don't need something very specific -- Just want to get these simulations running with minimum tweaking, given that these are tested gallery example and more importantly store the time-evolved metric, lapse and the shift for both these usecases. Thanks a lot in advance for your help! If you need anything do let us know. Best regards, Sandeep

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Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 15 Sep '25

15 Sep '25

Please update the Wiki with agenda items for Thursday's meeting. Thanks! https://docs.einsteintoolkit.org/et-docs/meeting_agenda --The Maintainers

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Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 10 Sep '25

10 Sep '25

1 0

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