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Weekly call at 12pm Thursday Eastern time
by rhaas＠illinois.edu 05 Feb '25

05 Feb '25

Title: CarpetX developer call When: 12pm Thursday Eastern time Join Zoom Meeting https://pitp.zoom.us/j/93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com

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Meeting minutes for 2025-01-30
by Cheng, Cheng-Hsin 30 Jan '25

30 Jan '25

Present: Erik, Roland, Yosef, Helvi, Swapnil, Liwei, Lucas, Cheng-Hsin Performance of Z4cow using Carpet vs CarpetX ======= Liwei compared the performance of Z4cow between Carpet and CarpetX versions, and found that the CarpetX version is slower than Carpet by 30% to 50%. - Setup: 1 AMR level, with subcycling, 128^3 grid on 1 MPI process, 32 time steps. - Erik suggested that timing information is needed to see which part is the most expensive. - Liwei is thinking about profiling using HPCToolkit, but will try using the Carpet timing information first. - Roland asked if Z4cow has been compared with LazEv in terms of performance, but this hasn't been done yet. - Liwei was able to re-run the tests and show the timing information at the end of the meeting - Erik pointed out that CarpetX does domain decomposition by default into 64 boxes whereas Carpet does not, so the CarpetX test will need to use a grid size of 128 for an even comparison with Carpet. - Erik suggested that the number of RHS calls could be different and that Liwei should check it with a counter. - Erik mentioned that the AMReX tile sizes affect the performance a lot, so Liwei should also experiment with using different tile sizes to get the best performance from CarpetX. Fix for NewRadX when symmetries are applied ====== - Roland asked about the status of the pull requests for the NewRadX fix. - Cheng-Hsin reported that the pull request under CarpetX has been reviewed but still awaits formal approval from Erik before it can be merged. - The pull request under SpacetimeX needs a reviewer, and Lucas volunteered. Subcycling paper ====== - Awaiting reviewing by co-authors, and there is still some text in the discussion that needs to be written up. Will ask people if they would like to be listed as co-authors or left out. Updates from Lucas ====== - Lucas is looking into dereferencing issues when using function pointers, and is also looking into calling functions directly instead. - Lucas, Steve, and Max (PhD student) have been testing hybrid Runge-Kutta integrators on BBH simulations, where some of the intermediate RK steps are replaced with the RHS evaluated at previous timesteps, making it a multi-step method. - The hybid method maintains the accuracy and maintains the RHS evaluated in previous steps, but the downside is that more memory may be required. - Comparing the BBH waveform using standard RK4, 2-step hybrid, 3-step hybrid methods, the error is small (maximum 1e-9), and the hybrid method runs much faster than standard RK4. - The code is in the branch feature/RKAB in the CarpetX repo, and Lucas showed how to add the hybrid RK method to an evolution thorn by adding tags to the state variables.

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Weekly call at 11am Thursday Eastern time
by rhaas＠illinois.edu 29 Jan '25

29 Jan '25

Title: CarpetX developer call When: 11am Thursday Eastern time Join Zoom Meeting https://pitp.zoom.us/j/93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com

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Weekly call at 12pm Thursday Eastern time
by rhaas＠illinois.edu 24 Jan '25

24 Jan '25

Title: CarpetX developer call When: 12pm Thursday Eastern time Join Zoom Meeting https://pitp.zoom.us/j/93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com

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Weekly call at 12pm Thursday Eastern time
by rhaas＠illinois.edu 22 Jan '25

22 Jan '25

Title: CarpetX developer call When: 12pm Thursday Eastern time Join Zoom Meeting https://pitp.zoom.us/j/93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com

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CarpetX call
by Haas, Roland 14 Jan '25

14 Jan '25

Join Zoom Meeting<https://pitp.zoom.us/j/93861697232> pitp.zoom.us/j/93861697232<https://pitp.zoom.us/j/93861697232> ID: 93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com Joining instructions<https://urldefense.com/v3/__https://www.google.com/url?q=https:**Aapplicati…>

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CarpetX call
by Haas, Roland 14 Jan '25

14 Jan '25

Join Zoom Meeting<https://pitp.zoom.us/j/93861697232> pitp.zoom.us/j/93861697232<https://pitp.zoom.us/j/93861697232> ID: 93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com Joining instructions<https://urldefense.com/v3/__https://www.google.com/url?q=https:**Aapplicati…>

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CarpetX call
by Haas, Roland 14 Jan '25

14 Jan '25

Join Zoom Meeting<https://pitp.zoom.us/j/93861697232> pitp.zoom.us/j/93861697232<https://pitp.zoom.us/j/93861697232> ID: 93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com Joining instructions<https://urldefense.com/v3/__https://www.google.com/url?q=https:**Aapplicati…>

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CarpetX developer's call re-scheduling
by Roland Haas 14 Jan '25

14 Jan '25

Hello all, With the new semester the previous meeting times no longer work for all. At this point *two* slots are needed: * Thu 11am US Eastern time (week 1, this week [except we already had a meeting]) * Thu 12pm (noon) US Eastern time (week 2, next week [our next meeting]) This would seem to ensure that everybody can make it to either the week 1 or week 2 slot (with weeks 1 and 2 alternating). I will (tentatively) move the calendar invites and email reminders to account for the new slots. Since we already had a meeting this week, our next meeting is *next week* Thu Jan 23rd 12pm (noon) US Eastern time using the usual Zoom call link: https://illinois.zoom.us/j/81532767368?pwd=bGJOL2xFdHJwRUFWTE55Vy9LczZmUT09 If you have non-movable conflicts, please raise any objections before Sunday Jan 19th, 2025. 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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Weekly call at 11am Monday Eastern time
by rhaas＠illinois.edu 10 Jan '25

10 Jan '25

Title: CarpetX developer call When: 11am Monday Eastern time Join Zoom Meeting https://pitp.zoom.us/j/93861697232 Join by phone (CA) +1 647-558-0588 Join using SIP 93861697232(a)zoomcrc.com

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