[Users] Meeting minutes for 2023-08-31

[Leo Rosa Werneck]

Hi all,

Einstein Toolkit Meeting - August 31, 2023

Chair        : Peter
Minute taker : Leo
Present      : Sam Cupp, Yosef Zlochower, Peter Diener, Leo Werneck,
               Zach Etienne, Roland Haas

* Next ET Release

  - Should CarpetX be enabled or disabled by default? Sam believes it would be
    weird to include all of the new thorns that depend on CarpetX and then have
    people do extra work to have access to them. This will force everyone to
    have a compiler that supports C++17, but this is not a particularly high
    bar. Erik also supports enabling it by default.

  - Roland said some modification might be needed for simulation factory to
    account for this. There is also some consideration about the default
    compiler, which would mostly affect the "generic" configuration. The new
    configuration would need to check the system until it finds a
    C++17-compatible compiler, something that is currently not done. Further,
    some older versions of GCC require you to pass additional options to link
    against the correct, "experimental" standard library.

  - Zach shared a useful list of supported C++ features by compiler:
    https://en.cppreference.com/w/cpp/compiler_support/17

  - Roland suggested enabling CarpetX now so that problems can be fixed as they
    appear.

  - Loop control, as it exists, prevents Carpet and CarpetX from existing in the
    same executable. The provided macros are drastically different for the two
    drivers because of the way looping is done in AMReX. One option is to have
    thorns require "Loop control" OR "Loop control X" so that the header file
    can pick the appropriate macros at compile time. This is not yet
    implemented, but Roland will work on it.

  - Peter should review GRHayLHDX, but skip GRHayLMHDX.

* Unanswered Questions on the Mailing List

  - There are bugs in POWER. Roland will look into it.

* Open Tickets:

  - #2754: there are different definitions of magnetic fields in the toolkit,
           differing by a factor of sqrt(4pi). Note that the evolution of GRMHD
           quantities is still consistent, as these factors are accounted for
           when computing the magnetic pressure that is used to compute the
           energy-momentum tensor. As Zach points out, this only affects very
           specific scenarios where direct comparisons between e.g., GRHydro and
           IllinoisGRMHD are performed.

  - In the future, it would be nice do modify the Seed_Magnetic_Fields thorns
    from WVUThorns* to provide a more user friendly way of setting up the
    magnetic fields (for example, the user can specify the ratio of magnetic to
    fluid pressure).

Next week's chair        : Zach
Next week's minute taker : Roland

Cheers,
Leo


------
Leonardo R. Werneck, Ph.D.
Postdoctoral researcher
Office EP 314 | Department of Physics | University of Idaho
875 Perimeter Dr. MS 0903
Moscow, ID 83844-0903, USA
leonardo at uidaho.edu <mailto:leonardo at uidaho.edu>
https://leowerneck.github.io <https://leowerneck.github.io/>
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