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snapenter - enter an N-body snapshot interactively into a file


snapenter [out=snapfile] [nbody=nbody] [time=time] [headline=string]


snapenter prompts for input from the screen of the basic data describing a snapshot file: masses, positions and velocities of each particle in an N-body system. The data are written into a file snap-file, in a standard N-body snapshot format. If not provided on the command line, snapenter will prompt for the name of snap-file and nbody, the number of particles.

To still enter snapshots interactively, but for a larger amount of bodies, the ‘‘205’’ format (see atos(1NEMO) ) can be used. An ascii file with masses, positions and velocities can be created with an editor, and atos(1NEMO) is used to convert this file to a proper snapshot(5NEM0) file.

Coordinates are not transformated to the center-of-mass coordinate system, for this the program snapcenter needs to be used.


The following parameters are recognized; they may be given in any order.
Output data is written into snap-file, in standard snapshot format.
Number of particles nbody in Nbody snapshot.
Time at which the snapshot applies (default: time=0.0).
Optional headline, which is written as the first item in the snapshot file, the next item being the snapshot itself.
In interactive mode you should set this to true, but in a case snapenter was used in a pipe (see EXAMPLE below), it cuts down a large number of messages. [Default: false].


A cleverly formatted ASCII table can also be piped into snapenter, if they only contain masses, positions and velocities in the following format:
  m1 x1 y1 z1 vx1 vy1 vz1
  m2 x2 y2 z2 vx2 vy2 vz2
  mN xN yN zN vxN vyN vzN
where the first number, N, is the number of particles. If that is not available in the file, specify it via the commandline.

See Also

atos(1NEMO) , snapprint(1NEMO) , snapcenter(1NEMO) , snapshot(5NEMO) .


Piet Hut


~/src/nbody/init    snapenter.c

Update History

28-Nov-86    V1.0: created             PIET
23-Apr-87    V1.1: created             PIET
10-Jun-88    V1.2: created             PIET
10-jul-89    V2.0: updated for new filestruct()    PJT
21-nov-90    V2.1: some defaults changed, NEMO 2.x    PJT
24-mar-94    added verbose= and the example    PJT

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