Date: Tue, 16 Jun 2026 00:00:00 +0000

From: MAKINO Taiki makino.taiki.g6@s.mail.nagoya-u.ac.jp To: "users@einsteintoolkit.org" users@einsteintoolkit.org Subject: [Users] ET Simulation Error

Dear Einstein Toolkit Team

I am a new Einstein Toolkit user and have a simulation error.

I can run DNSdata_test.par with GRHydro, but I cannot run it when I switch GRHydro to IllinoisGRMHD. In detail, I changed the activethorns from GRHydro to IllinoisGRMHD, and added some activethorns such as GRHayLib, GRHayL and GRHayLHD.

In addition, I commented out parameters of GRHydro like ?GRHydro::sources_spatial_order?. And, I wrote HydroBase::evolution_method = "IllinoisGRMHD?. The error message is as follows:

?WARNING level 0 from host hubble process 22 in thorn Cactus, file /data/usr/Cactus/configs/sim/build/Cactus/main/SetParams.c:93: -> CCTKi_SetParameter: Error at line 36 in parameter file /data/usr/sim_Result/test_BNS_GW_Piecewise4_Cactus_Illinois8/output-0000/DNSdata_test.par while activating thorns?

Also, one of participants of the Einstein Toolkit workshop advised that I had to activate DNSdata which I had commented out and to comment out parameters of thorns which I did not activate. After making these changes, a different error appeared. It is the following:

WARNING level 0 from host hubble process 0 in thorn Cactus, file /data/usr/Cactus/configs/sim/build/Cactus/main/SetParams.c:93: -> CCTKi_SetParameter: Error at line 37 in parameter file /data/makino/test_BNS_GW_Piecewise4_Cactus_Illinois9/output-0000/DNSdata_test_copy.par while activating thorns.

The list of activated thorns is provided below for reference:

ActiveThorns = "Boundary CartGrid3D CoordBase Fortran InitBase IOUtil LocalReduce SymBase Time" ActiveThorns = "AEILocalInterp" ActiveThorns = "MoL Slab SpaceMask SphericalSurface" ActiveThorns = "Carpet CarpetInterp CarpetInterp2 CarpetIOASCII CarpetIOHDF5 CarpetIOScalar CarpetLib CarpetIOBasic CarpetReduce CarpetRegrid2 CarpetSlab CarpetTracker CarpetMask LoopControl" ActiveThorns = "Formaline" ActiveThorns = "HTTPD Socket" ActiveThorns = "NaNChecker TerminationTrigger TimerReport" ActiveThorns = "ADMbase ADMcoupling ADMmacros CoordGauge StaticConformal" ActiveThorns = "RotatingSymmetry180 ReflectionSymmetry" ActiveThorns = "Constants TmunuBase HydroBase " ActiveThorns = "QuasiLocalMeasures" ActiveThorns = "EOS_Omni" ActiveThorns = "GRHayLib" ActiveThorns = "GRHayL" ActiveThorns = "IllinoisGRMHD" ActiveThorns = "SummationByParts" ActiveThorns = "GenericFD NewRad" ActiveThorns = "ML_BSSN ML_BSSN_Helper ML_ADMConstraints" ActiveThorns = "Hydro_Analysis" ActiveThorns = "Dissipation" ActiveThorns = "DNSdata" ActiveThorns = "GRHayLHD?

The line reported in the second error (line 37) corresponds to:

ActiveThorns = "GRHayLHD"

Am I missing any required thorns, parameter settings, or something else for using IllinoisGRMHD with DNSdata_test.par?

Thank you very much for your time and assistance.

I have attached the parameter file for reference. If any additional information would be helpful, I would be happy to provide it.

Best regards,

Taiki Makino Graduate School of Science, Nagoya University makino.taiki.g6@s.mail.nagoya-u.ac.jp

Dear Taiki,

You should remove the GRHayL from the active thorns as the thorn name is GRHayLib for that. And you don't need HydroBase::evolution_method = "IllinoisGRMHD" for IGM. You activate both IGM and GrHaylHD you should choose one.

Please have a look at the example parfiles: Cactus/arrangements/GRHayLET/IllinoisGRMHD and also in Cactus/arrangements/GRHayLET/GRHayLHD.

Best regards,

Beyhan.