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lagrange_radii - find the Lagrange radii of a stellar system


lagrange_radii [parameter=value]

requires NEMO version 3.0.13 or higher, see


lagrange_radii finds the radii of spheres centred at the origin x=(0,0,0) that contain a given fraction of the total mass. The code is significantly faster than a full sort of all body radii.

lagrange_radii may be used to create a stopfile to trigger the stopping of a running N-body simulations that is being analysed by lagrange_radii.


Input snapshots 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
The lagrange radii are computed for every fractional mass contained in the comma separated list (up to 100). Default: 0.01,0.03,0.1,0.3,0.5,0.7,0.9,0.97,0.99
times=time range(s)
Range(s) of simulation times, for which snapshots shall be processed. Default: all.
If given, snapshots are written in NEMO snapshot format to file with same body data as the input, unless give specifies otherwise. No default.
If given, only body data indicated by IOstring (and present in the input) are written out with the snapshot output. No default.
If snapshots are written out, the outputs are made every val simulation time units. If val=0, every snapshot processed is written out. Default: 0.
A table of the simulation time and Lagrange radii (in the order the fractional masses are given) is written to file, appending an existing file, if applicable. If not given, Lagrange radii are written to stdout. No default.
If given, the a stopfile will be created, IF the condition defined with the next options is satisfied. See also gyrfalcON(1falcON) . No default.
If stopfile is given, R_stop is the numth Lagrange radius. Default: 0.
If val>0, the stop condition is R_stop < val.

If val<0, the stop condition is R_stop > |val|.

No default.

If true, use R_stop/R_stop(t_initial) instead of R_stop in the stop condition. Default: f.
If given, do not stop before simulation time val. No default.
Create the stopfile val simulation time units after the stop condition was first satisfied. Default: 0.


Useful for isolated stellar systems only.

see also

density_centre(1falcON) , gyrfalcON(1falcON)


falcON/doc/user_guide.pdf                         User Guide for falcON


Walter Dehnen                    
update history of this man page
18-May-2004    first version of manual  WD

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