Re: GADGET4 won't load mass block for variable masses?

From: Volker Springel <vspringel_at_MPA-Garching.MPG.DE>
Date: Fri, 19 Mar 2021 13:27:24 +0100

Hi Balázs,

I see that you have the option LEAN enabled, which however only works for equal particle masses (and this is why a mass block is never read/written in this case). I'd suggest to try again after disabling LEAN.


> On 19. Mar 2021, at 12:54, Balázs Pál <> wrote:
> Dear Gadget community!
> I'm trying to run GADGET4 with variable masses and with only a single particle type. My IC file is created using the `glio` python package ( and thus it is encoded as a legacy format 1 file. The masstable in the header is set to 0 for all of the particle types, and a mass block is added to the file as required, in the very same manner as the header, ID, position and velocity blocks.
> The output file itself seems to be correct, because the GadgetViewer 1.1.1 tool loads it without any problem and also displays the variable masses correctly using the "color by property > Mass" display option. However, when the file is loaded as an IC for a GADGET4 executable which was compiler with the GADGET2_HEADER option, the masses (the mass block itself) are not loaded, as shown in the output log, when GADGET4 loads the IC:
> ```
> ...
> [19/03/21 11:15:58] READIC: Reading file `/path/to/IC_file' on task=0 and distribute it to 0 to 3.
> [19/03/21 11:15:58] READIC: reading block 0 (Coordinates)...
> [19/03/21 11:15:58] READIC: reading block 1 (Velocities)...
> [19/03/21 11:15:58] READIC: reading block 2 (ParticleIDs)...
> [19/03/21 11:15:58] READIC: reading done. Took 0.000970569 sec, total size 0.219276 MB, corresponds to effective I/O rate of 225.926 MB/sec
> ..
> ```
> GADGET4 stops at the beginning of the very first iteration, since it detects a zero mass system (with error, that mass content corresponds to Omega_m = 0, but I've specified Omega_m=0.3111 in the parameterfile).
> Where's the problem? What do I need to do to successfully start this GADGET4 simulation with variables masses, besides those I've discussed above?
> The IC file that I try to run is too large, but I'm sending the full log and my file too as attachments to this message.
> Thanks for any help in advance!
> Regards,
> Balázs
> <run_N1024_GTF2.log><>
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Received on 2021-03-19 13:27:24

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