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snapcmp - compare two N-body snapshots
in2=snap_file [parameter=value] ...
snapcmp is a flexible tool
for comparing two N-body snapshots on a particle by particle basis. An arbitrary
‘‘observable’’ defined in terms of the basic components of a body(3NEMO)
be specified for the comparison. Particles are compared by differencing
their observables, or by computing the observable applied to a differenced
particle. These options cover most of the common methods of comparing N-body
snapshots. The default settings compute the magnitude of the configuration-space
displacements between each pair of particles.
The program simply outputs
eight numbers: time of the first snapshot, are the minimum, lower quartile,
median, upper quartile, maximum of the measured differences, and the mean
and dispersion of the distribution.
The following parameters are
- Input data is read from snap_file1
and snap_file2, which must be in snapshot(5NEMO)
format. Default: none.
- Data with time values within time_range1
and time_range2 will be read from snap_file1 and snap_file2, respectively.
- obs_expression is the observable used
to compare the particles. See bodytrans(1NEMO)
for the form of obs_expression.
Default: r, which compares the positions of particles.
flag is true, particles are compared by subtracting the components of one
from the components of the other, and evaluating the observable obs on
this ‘‘differenced particle’’. Otherwise, obs is evaluated for each particle,
and the results are differenced. Default: true.
- If flag is
true, the differenced observable is divided by the value of obs computed
from the particle in snap_file1. Otherwise, the differenced observable is
used. Default: false.
- Show (10-base) logarithms of the values instead
of their linear values Default: false.
src/nbody/reduc/snapcmp.c source code for snapcmp, snapcmphist and
Joshua E. Barnes.
23-may-88 V1.0 created? Josh
29-mar-94 V1.3 added time to output Peter
15-apr-04 V1.5 added headline= to the plotting versions and mean,sigma to
the output PJT
16-jul-09 V1.6 added log= PJT
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