Users January 2026

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11 participants
21 discussions

Loss of convergence with subcycling in time
by Miguel Zilhão 17 Feb '26

17 Feb '26

hi all, we've recently added the option to compute the Gauss constraint in the ProcaEvolve thorn (https://bitbucket.org/canuda/proca/src/experimental_miguel/ProcaEvolve/) and we were surprised to see that, even for very small evolutions of a simple (unperturbed) charged black hole, this constraint violation does not converge. of course everything is converging just fine at t=0, but once the evolution starts, convergence is lost really quickly. after experimenting with different things, i think i've narrowed the issue down to the subcycling in time. i've attached some plots as well as the corresponding parameter files. these plots are not convergence tests, it's just what i'm observing with and without subcycling in time (everything else is the same as you can see from the parfiles). these are evolutions for a single charged BH, with Q=0.2. in one of the parfiles (LeanBSSN_RN_Q0.2_nosubcycl_hf40_202509.par) all timelevels update at the same rate with Carpet::time_refinement_factors = "[1, 1, 1, 1, 1, 1, 1]" for the other parfile (LeanBSSN_RN_Q0.2_hf40_202509.par), all timelevels update at the same rate *except* the two inner ones. for the "base" grid functions, i see no noticeable difference insofar as i've checked, but for the Gauss constraint violation the results are very different as you can see from the plots attached: - in the gc_x_RN_nosubcycl.pdf plot, everything looks fine - in the gc_x_RN_subcycl.pdf case, notice how a lot of noise propagates from the two inner refinements levels -- the ones that updated more frequently than the rest. the problem is that this noise is not contained in the buffer region (if it was, we'd be fine), but propagates out, contaminates the rest of the grid, and totally ruins any convergence study. actually a similar thing also happens for the hamiltonian constraint -- plots also attached (hc_x_RN_nosubcycl.pdf, hc_x_RN_subcycl.pdf) -- but in this case the effect is smaller and it doesn't spoil convergence studies. so i was wondering whether this is at all expected and/or if there are some parameters or setting that we may have overlooked? thanks, Miguel

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meeting minutes for 2026-01-29
by Roland Haas 29 Jan '26

29 Jan '26

Present: Roland, Peter, Deborah, Aryan Saju, Beyhan, Cheng-Hsin, Johnny, Maxwell, Nikolai, Noora, Steve Chair: Deborah Minutes: Roland ET release planning =================== * gallery examples is firming up * timeline: https://docs.einsteintoolkit.org/et-docs/Release_Details#Details_for_ET_202… * currently ahead of schedule * Beyhan will handle BHNS merger * Johnny will run Poisson equation * Noora will run axi-dilaton example * tentatively starting examples April 1st once most changes are in * Johnny may be able to run testsuite on Frontera * Testsuite runner needed for expanse * will need reviewers. Peter will review Bhahaha (champion is Zach) Questions on mailing list ========================= * no questions found Open tickets ============ * Roland is collecting tar files, Frank created them in the past, but they are lost https://bitbucket.org/einsteintoolkit/tickets/issues/2673/provide-historica… * Roland has started implementing STORAGE statements https://bitbucket.org/einsteintoolkit/tickets/issues/2913/support-enabling-… * Roland commented on https://bitbucket.org/einsteintoolkit/tickets/issues/2908/cactus-fixed-arg-… Max (Morris) will update * Roland to take a look at https://bitbucket.org/einsteintoolkit/tickets/issues/2899/bhns-with-ellipti… on Marenostrum * Peter and Zach plan to get back to, wanted to compare results https://bitbucket.org/einsteintoolkit/tickets/issues/963/improve-mclachlan-… * Roland and Steve will pick up again on https://bitbucket.org/einsteintoolkit/tickets/issues/2909/remove-tags-from-… Roland to add comments to ticket * Steve and Roland discussed: https://bitbucket.org/einsteintoolkit/tickets/issues/2910/carpetx-add-optio… Roland suggests that this was added to avoid outputting bad data in the physical boundary, asks whether it would not be better to have correct data there * Re-review is required https://bitbucket.org/einsteintoolkit/tickets/issues/2898/carpetx-interpola… Poke Erik about review. * Roland will provide a reproducer for https://bitbucket.org/einsteintoolkit/tickets/issues/2888/race-condition-wr… Tickets for review ================== * Roland to look into https://bitbucket.org/einsteintoolkit/tickets/issues/2862/update-spacetimex… Any other business ================== * North American ET School and Workshop at UIUC planning is ongoing, no firm date set yet. Will pick up again in the coming weeks. 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://pgp.mit.edu .

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Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 28 Jan '26

28 Jan '26

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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Re: [Users] My problems with Thorn
by Roland Haas 28 Jan '26

28 Jan '26

Hello Abderrahim El Khou, You do not really have to run the tutorial notebooks through jupyter, you can just use jupyter as a viewer for the information and follow along using the video recording. If you do not have Jupyter installed then github's online viewer also works. e.g.: https://github.com/EinsteinToolkit/jupyter-et/blob/master/tutorial-server/n… you can see the content that goes into the individual files in the cells that start with %writefile and the remainder of that cell is the content written to the file. SimpleWave.m is an example on how to use Kranc to generate a thorn. If you intent to use Kranc then it is a good first example to start with. Many more complex thorns are generated using Kranc eg the WeylScal4 thorn, the mclachlan thorns and the EinsteinExact thorns. If you would rather write a thorn using C/C++ or Fortran then Yosef's lecture on how to create a heat equation / wave equation may be your best starting point. Or you can use one of the very old examples of how to implement a wave equation, like the attached one. There's not video recording of it though. Yours, Roland > [CAUTION: Non-UBC Email] > > I found one problem here, i don't work with Juypter so the language is > confusing me a little bit so i start following the example that you give me > at the first "the SimpleWave.m" my question here is it necessarily to take > the same process for any create of other thorns or the is just for the > simple wave, if no what is the solution please. > Thank you a lot sir. > > On Tue, Jan 27, 2026 at 8:36 PM Roland Haas <rhaas(a)mail.ubc.ca> wrote: > > > Hello Abderrahim El Khou, > > > > > if it possible i want a tutorial how to write my own thorn if it is > > > thank you a lot > > > > Kranc has an example (the SimpleWave.m one) in: > > > > http://kranccode.org/documentation.html > > > > though note that it uses the `Bin/kranc` wrapper so that all required > > Mathematica packages are being found. > > > > There are a number of recorded tutorials on how to write a new thorn > > that you can find in: > > > > https://www.youtube.com/playlist?list=PLRxi-yB7cTGc6_RtPA8g3qm2XOGfmvkoH > > > > for example: > > > > https://youtu.be/PcuPhODh34o?si=tAaM54bRT584N7Qo > > > > There's also the CreatingANewThorn-*.ipyb notebooks in: > > > > > > https://github.com/EinsteinToolkit/jupyter-et/tree/master/tutorial-server/n… > > > > which are actually used in the recording above. > > > > 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://pgp.mit.edu . > > 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://pgp.mit.edu .

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My problems with Thorn
by Abderrahim El Khou 27 Jan '26

27 Jan '26

Good evening sir, I'm having trouble writing my own thorn; i might have overlooked something important. I'm working on a Linux Ubuntu system; I have Mathematica and i think the problem is with its related with the Kranc. I want to know where i missed the solution.

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Fwd: [atpesc-references] ATPESC 2026
by Helvi Witek 27 Jan '26

27 Jan '26

Dear all, please see below the announcement for the Argonne Training Program on Extreme-Scale Computing, and opening for applications. It is open for PhD students and postdocs. Some of my group members attended the school in recent years and found it very useful. Best wishes, Helvi --------------------------------------------- Dr. Helvi Witek Associate Professor Department of Physics University of Illinois at Urbana-Champaign 247 Loomis Lab 1110 W Green St Urbana, IL 61801 --------------------------------------------- -------- Forwarded Message -------- Subject: [atpesc-references] ATPESC 2026 Date: Tue, 27 Jan 2026 03:03:37 +0000 From: Loy, Raymond M. <rloy(a)alcf.anl.gov> To: atpesc-references(a)extremecomputingtraining.anl.gov <atpesc-references(a)extremecomputingtraining.anl.gov> Dear friends of ATPESC, I am reaching out to you because you have previously recommended students to attend ATPESC. If you know of any suitable candidates for this year, please let them know about the opportunity. Thank you! Ray ——— Apply now to learn the tools and techniques needed to carry out computational science on the world's most powerful supercomputers. *ALCF ANNOUNCEMENT* ATPESC 2026: Applications due February 25 ATPESC 2026 <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…> ------------------------------------------------------------------------ The annual Argonne Training Program on Extreme-Scale Computing is set to take place July 26 - August 7, 2026. Submit your application by February 25 for an opportunity to learn the tools and techniques needed to carry out computational science on the world's most powerful supercomputers. ATPESC participants will have access to DOE’s leadership-class systems at the ALCF, OLCF, and NERSC. APPLY HERE <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…> *ATPESC** Q&A WEBINAR* Join us on February 5, 2026, for a webinar that will provide a brief overview of ATPESC and feature an open Q&A session about the application process. This is a great opportunity to ask any questions you have about the program. REGISTER FOR WEBINAR <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…> *PROGRAM CURRICULUM* Renowned scientists and leading HPC experts will serve as lecturers and guide the hands-on training sessions. The core curriculum will cover: * Computer architectures * Numerical algorithms and mathematical software * Software productivity and sustainability * Data analysis, visualization, I/O, and methodologies for big data applications * Performance measurement and debugging tools * Machine learning and data science *ELIGIBILITY AND APPLICATION* Graduate students, postdocs, and computational scientists interested in attending ATPESC can review eligibility and application details on the website <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…>. There are no fees to participate in ATPESC. Domestic airfare, meals, and lodging are also provided. *Application deadline: February 25, 2026*. /ATPESC// is supported by the DOE Office of Science Advanced Scientific Computing Research Program./ ------------------------------------------------------------------------ linkedin <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…>facebook <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…>youtube <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…>Instagram <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…> US Department of Energy Office of Science Argonne Leadership Computing Facility *Argonne Leadership Computing Facility* 9700 South Cass Avenue, Lemont, IL 60439 www.alcf.anl.gov <https://urldefense.com/v3/__https://urldefense.us/v3/__https:/*links-1.govd…> | media(a)alcf.anl.gov

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Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 26 Jan '26

26 Jan '26

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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meeting minutes for 2026-01-22
by keithdow＠keithdow.net keithdow＠keithdow.net 24 Jan '26

24 Jan '26

[Users] meeting minutes for 2026-01-22 Present: Roland, Keith, Steve, Beyhan, Maxwell, Cheng-Hsin, Deborah, Lucas, Leo Nikolai, Jordan ET release: Dec 1: Step 1 *Release Coordinator: Steve *Coordinator Assistant: *Release Name: Hypatia *Test Runners: Jan 1: Step 2 *Release timeline *Gallery Runners: **Leo - **Deborah - GW15 **Johnny **Beyhan - TOV *Testers: **Roland – Jan 22: Step 3 *Add call for new features to the website *These are the things to be included as of now **- LSU: Cottonmouth **- UIUC: CandudaX **- Idaho: Bhahaha Mar 1: Step 4 *Choose features, update master thornlist this wonth *Find reviewers for features *Decide on release-critical compute systems *Regenerate auto-generated thorns for the ﬁrst time Apr 1: Step 5: Start testing *Release-critical testing May 1: Step 6: Release Prep *Feature Freeze *Create Zenodo item *Draft Release Announcement *Conntact contributors and release team about inclusion Jun 1: Step 7: Release ** Unanswered Question on Mailing List ** *Safe check of variable Coordinates::volume_form_state **Volume form grid function depends on coordinates. (Thornburg 04) **Multipatch solution has issue in the overlap **lucas, to make things consistent ** Open Tickets & Tickers for Review ** * #2898 Needs review * #2908 Roland to comment on PR * #2909 Steve has a PR. Roland to take a look.

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Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 21 Jan '26

21 Jan '26

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Safe check of variable Coordinates::volume_form_state
by Jordan Nicoules 20 Jan '26

20 Jan '26

Dear all, I'm trying to extend our analysis thorn to tackle multipatch grids built with Llama. I want to use Coordinates::volume_form in the computation of volume integrals, by setting the corresponding parameter Coordinates::store_volume_form = yes. Our standard use case relies on Coordinates::coordinate_system = "Thornburg04", for which it works like a charm. However, except for this system and the analogous Thornburg13 (I have not tested it so far), it seems the variable Coordinates::volume_form_state is not modified nor initialized, whatever the value of the parameter Coordinates::store_volume_form. That makes the parameter insufficient by itself to perform checks. Moreover, since the flag is not initialized, we also can't simply check its value, which can be polluted. I have tried to use Carpet::poison_new_timelevels = yes and CarpetLib::poison_new_memory = yes, but it didn't seem to solve the issue. Hence, I would like to ask if there's another way to check for uninitialized values, a safe way to use the variables I mentioned in a general case, or any information/subtlety I may have missed? Ultimately, I can directly check Coordinates::coordinate_system, and output a warning/error if it's not of the types mentioned above. That feels a bit unsatisfactory, although I may default to it. Thank you very much for any help or insight you can provide! Best, Jordan Nicoules

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