HTML automatically generated with rman
Table of Contents


uns_addgravity - adds gravity to a snapshot; using falcON (public version)


uns_addgravity [parameter=value]


uns_addgravity it’s based on addgravity program by Walter Dehnen (WD). It uses Walter Dehnen’s force algorithm of complexity O(N) (falcON), to add the gravitational potential and accelerations to an UNS snapshots.


Input snapshots are read from file, which must an UNS snapshot format (NEMO, Gadget1/2/3, Ramses, etc..). If file=-, input is expected from stdin, useful for piping data from another program. Default: required
Snapshots are written in NEMO snapshot format to file with same body data as the input plus acceleration and potential. Default: required.
Select particles. Set of particles must be selected using the ":" range operator, separated by a comma. E.g. select=0:9,10:19 would select two sets of 10 particles, or by component (gas,halo,stars,bulge,disk,bndry) for Gadget/Ramses files. E.g. select=gas,stars . Default: required.
times=time range(s)
Range(s) of simulation times, for which snapshots shall be processed. Default: all.
The (globally constant) softening length is set to val. For details, see documentation in the user guide. Default: 0.05.
The softening kernel is taken to be the Pnum kernel (see the documentation in the user guide). Default: 1.
The tolerance parameter for falcON is set to val. It is recommended to stick to the default or smaller value, but see the discussion in the falcON user guide Default: 0.6.
In building the tree, a cell containg num bodies or less is not splitted. Default: 6.
if true, add a trailing number to the first output file [f]
offset=time offset
+/- time offset between two consecutives snapshots [0.01]
If true, give some verbose output [t].

see also

addgravity(1falcON) gyrfalcON(1falcON) , getgravity(1falcON)

Dehnen, W., 2000, ApJ, 536, L39
Dehnen, W., 2002, JCP, 179, 27


falcON/doc/user_guide.pdf                         User Guide for falcON


Jean-Charles LAMBERT
update history of this man page
17-Mar-20    first version of manual  JCL

Table of Contents