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Einstein Toolkit Meeting Reminder
by rhaas＠mail.ubc.ca 07 Oct '26

07 Oct '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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Einstein Toolkit Meeting Reminder
by rhaas＠mail.ubc.ca 07 Oct '26

07 Oct '26

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Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 05 Oct '26

05 Oct '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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Geodesic: aei sampler on GW150914 (BBH AMR) -- verified reproducible (this week's users call)
by Yuhua Li 01 Oct '26

01 Oct '26

Dear all, Following my previous updates, I would like to report progress on applying the samplers to the GW150914 binary-black-hole (BBH) spacetime on a 3- level Carpet AMR mesh -- the first fully realistic (non-stationary) test case for the geodesic probe. Completed this week: the aei sampler (metric_interp=aei, time_interp= linear). The 100-particle geodesic run at 256 resolution reproduces the reference run exactly: all compared steps (t = 0 .. 0.3356, 40 particle blocks of 100) agree to full double precision, with 0 dropped particles and 0 NaNs. At 128 resolution the t=0 block likewise matches a 2048 reference to full precision, and the residual difference at t=0.2753 (position ~5e-4) is consistent with the expected convergence of the sampler. In short, aei on the GW150914 AMR evolution is now verified and reproducible. Still under test (no result this week): the remaining samplers (local27 and its time-linear variant l27lin, plus carpet) on the BBH AMR mesh. In particular l27lin shows particle loss in the strong-curvature region near the horizons; I am debugging the metric/Christoffel sampling path there. I have no conclusion to report on them yet. So this week's deliverable is a single, clean result: aei on GW150914 is verified reproducible. The other samplers on the BBH AMR remain under verification, and I will report a concrete result once they pass. As before, I am most comfortable continuing in writing. Any questions or suggestions on the strong-curvature path are welcome. Best regards, Yuhua Li

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meeting minutes for 2026-10-01
by Roland Haas 01 Oct '26

01 Oct '26

Present: Roland, Lucas,, Zach, Max, Nikolai Chair: Zach Minutes: Roland ET summer school recordings --------------------------- * all presentations uploaded * should be made public shortly after Oct 2nd wiki transition --------------- * no updates accumulated updates after release --------------------------------- * McLachlan: no updates unanswered questions -------------------- * no new questions AI policy document ------------------ * there was a discussion about creating a AI policy usage guideline, similar to what other projects have * connected to AI for NR efforts: https://github.com/AI-for-NR/AI-for-NR * will continue the discussion * Zach reports that we have received AI based contributions, will continue to accept them and handle in a polite manner, pointing to policy if required (eg thorns are created for science reasons) Open tickets ------------ * https://github.com/EinsteinToolkit/tickets/issues/2974 "CarpetX: Support summation by parts derivative operators". Roland asked about a science application code using them. Zach suggests a gallery example to illustrate their use. * https://github.com/EinsteinToolkit/tickets/issues/2973 "Add support for Multi-step Runge-Kutta methods in CarpetX/ODESolvers" contains a cleaned up implementation of the methods of https://arxiv.org/abs/2603.05763 . Request to add groupstoragencrease as full Cactus API * https://github.com/EinsteinToolkit/tickets/issues/2956 "CarpetX: Allow conditional expressions after SCHEDULE declarations in schedule.ccl" has two competing pull requests. Those should be merged. ** would make most of https://github.com/EinsteinToolkit/tickets/issues/2948 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 30 Sep '26

30 Sep '26

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Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 28 Sep '26

28 Sep '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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Geodesic: status on the multi-process (MPI) + AMR path (this week's users call)
by Yuhua Li 24 Sep '26

24 Sep '26

Dear all, Following my presentation of Geodesic at the previous weekly users call, I would like to give a brief status on the one item I flagged as an open limitation: exercising the multi-process (MPI) configuration on a Carpet AMR evolution. The single-process + AMR runs already reproduce the unigrid reference orbits with the three samplers, with no lost particles and no NaNs. Since then I have been working on the MPI path, but the work is still under test: current MPI + AMR runs still show particle loss with non-finite metric samples, and I am debugging the cause. I do not yet have a clean, reproducible result, so I have no conclusion to report this week. In short: no new deliverable on the MPI + AMR path this week -- it is still under verification. I will report a concrete result as soon as the verification passes. I remain available to discuss, and as before I am most comfortable continuing in writing. Any questions are welcome. Best regards, Yuhua Li

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meeting minutes for 2026-09-24
by rhaas＠mail.ubc.ca 24 Sep '26

24 Sep '26

Present: Roland, Peter, Steve, Beyhan, Jordan, Maxwell, Nikolai, Zach Transition wiki to GitHub ------------------------- * Steve presented current state of attempt to transition MediaWiki wiki to GitHub wiki * please take a look at https://github.com/EinsteinToolkit/wiki/wiki * ticket at https://github.com/EinsteinToolkit/tickets/issues/2256 * access is controlled via GitHub org for ET MacLachlan updates ------------------ * Peter is still trying to run on LSU machines, will contact Steve to test out simfactory settings Mailing list questions ---------------------- * Steve will respond to http://lists.einsteintoolkit.org/pipermail/users/2026-September/010041.html ** Zach provided the inclusion criteria: https://www.einsteintoolkit.org/contribute.html * we are not clear what to do about http://lists.einsteintoolkit.org/pipermail/users/2026-September/010034.html Open tickets ------------ * https://github.com/EinsteinToolkit/tickets/issues/2956 has a branch and Erik has a (separate) pull request https://bitbucket.org/cactuscode/cactus/pull-requests/180 and https://bitbucket.org/cactuscode/cactustest/pull-requests/7 * https://github.com/EinsteinToolkit/tickets/issues/2974 Peter will take a look at this summation-by-parts contribution * https://github.com/EinsteinToolkit/tickets/issues/719 concerns updating mailman, mailman 2 is now old enough to be no longer supported and we are in the process of upgrading to mailman 3 * https://github.com/EinsteinToolkit/tickets/issues/2960 "CarpetRegrid2: failure to regrid on relative radius change - possible underlying race condition" has a reproducer and should be addressed * https://github.com/EinsteinToolkit/tickets/issues/2965 "GetComponents option to obtain new branch", is looking for a reviewer. Steve will try * https://github.com/EinsteinToolkit/tickets/issues/2973 "Add support for Multi-step Runge-Kutta methods in CarpetX/ODESolvers" Steve is pushing to have this included * https://github.com/EinsteinToolkit/tickets/issues/2961 "util_ExpressionEvaluate fails with custom evaluator" Steve has PR that he will link * https://github.com/EinsteinToolkit/tickets/issues/2909 "Remove TAGS from interface.ccl" has comments 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 23 Sep '26

23 Sep '26

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