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name

getgravity - computes gravity at sink positions; using falcON (public version)

synopsis

getgravity [parameter=value]

requirement

requires NEMO version 3.0.13 or higher, see http://www.astro.umd.edu/nemo.

description

getgravity uses Walter Dehnen’s force algorithm of complexity O(N) (falcON), to compute the gravitational accelerations and potential generated by one set of bodies (sources) at the positions of another set of bodies (sinks).

parameters

srce=file
Input snapshots of the source bodies are read from file, which must be in NEMO snapshot format. If file=-, input is expected from stdin, useful for piping data from another program. Default: required.
sink=file
One input snapshot (in NEMO snapshot format) with the sink positions is read from file. Default: required.
out=file
Output snapshots with the position, potential, and acceleration of the sink positions is written out to file for every snapshot processed. Default: required.
times=time range(s)
Range(s) of simulation times, for which srce snapshots shall be processed. Default: all.
eps=val
The (globally constant) softening length is set to val. For details, see documentation in the user guide. Default: 0.05.
kernel=num
The softening kernel is taken to be the Pnum kernel (see the documentation in the user guide). Default: 1.
theta=val
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.
Ncrit=num
In building the tree, a cell containg num bodies or less is not splitted. Default: 6.

see also

gyrfalcON(1falcON) , addgravity(1falcON) 


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

files


falcON/doc/user_guide.pdf                         User Guide for falcON

author


Walter Dehnen                              walter.dehnen@astro.le.ac.uk
update history of this man page
18-May-2004    first version of manual  WD

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