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snapcmphist - compare two N-body snapshots and plot histogram
in1=snap_file in2=snap_file [parameter=value] ...
is a flexible tool for comparing two N-body snapshots on
a particle by particle basis, but snapcmphist plots a histogram of the
resulting values. An arbitrary ‘‘observable’’ defined in terms of the basic
components of a body(3NEMO)
may 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
The following parameters are recognized.
Joshua E. Barnes.
- 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. At present only the first pair
of frames within these ranges will be analyzed. Default: "all", which has
the effect of using the first pair of frames in the files.
- 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
- If 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.
- Number of equally-spaced
bins to use for histogram. Default: 8.
- Range of values
covered by histogram; of the form low:high. Default: 0.0:1.0.
- Label for x-axis. Default is obs_expression.
- Number of
equally-spaced tickmarks along x-axis. Default: 3.
- If specified,
use as max value on vertical axis; if not, program uses highest histogram
bin to pic scaling. Default: none.
- Label for y-axis.
- Number of equally-spaced tickmarks along
y-axis. Default: 3.
- Verbiage at the top right of the graph. Default:
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