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Name

snapgadget - convert snapshot to GADGET format

Synopsis

snapgadget [parameter=value]

Description

snapgadget converts data from standard snapshot(5NEMO) format into gadget(lNEMO) .

Although gadget(lNEMO) has several flavors of particles (halo, disk, bulge, stars, gas), this version can only handle a limited set due to current limitations in the way snapshot’s are handled.

Some programs (e.g. AHF) that need proper cosmological information in a gadget header, will need these explicitly passed via a set of parameters (see below).

Parameters

The following parameters are recognized in order; they may be given in any order if the keyword is also given. Use --help to confirm this man page is up to date.
in=
Input file (snapshot format). No default.
out=
Output file (gadget format). Each snapshot is placed in its own file, and "%t" is replaced with the time of the snapshot (useful for times=all). No default.
N=Nhalo,Ndisk,Nbulge,Nstars
Nhalo,Ndisk,Nbulge,Nstars needs to be specified for the sub-components as GADGET wants them. Note the current version does not handle gas particles. No default.
M=Mhalo,Mdisk,Mbulge,Mstars
The masses (per particle) of each of the components listed in the N= keyword. You only need this if no masses are present. Note in this mode it is not possible to have different masses per component. Default: not used.
times=
Times of the snapshots to select for output. Default: all
swap=
Force swaping bytes for other-endian machines [f] z= Current Redshift [0]
z=
Current redshift [0]
box=
Box size (Mpc/h) [128]
omega0=
Omega_0 [0.3]
lambda0=
OmegaLambda0 [0.7]
h=
HubbleParam [0.75]

Caveats

There is an option to run gadget in double precision mode, their output files may not be compatible with this version of the program.

Such "unformatted binary" files are limited to 4GB per block.

See Also

gadgetsnap(1NEMO) , nemo2gadget(1NEMO) , gadget2nemo(1NEMO) , uns2uns(1NEMO) , g2info(1NEMO) , snapshot(5NEMO) , gadget(5NEMO)

http://www.mpa-garching.mpg.de/gadget/

https://gitlab.mpcdf.mpg.de/vrs/gadget4/-/blob/master/documentation/06_snapshotformat.md

Author

Jeremy Bailin

Update History


8-sep-03    V0.1 Created    J.Bailin
8-sep-03    V0.2 minor mods on order of arguments, fix missing %t case    PJT
21-jun-11    V1.0 add some reasonable cosmo defaults, in case they’re needed    PJT
22-jun-11    V1.1 add M=    PJT
19-jan-22    updated man page format; added links    PJT


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