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Name

snapcmphist - compare two N-body snapshots and plot histogram

Synopsis

snapcmphist in1=snap_file in2=snap_file [parameter=value] ...

Description

snapcmphist like snapcmp(1NEMO) 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 particles.

Parameters

The following parameters are recognized.
in1=snap_file1
in2=snap_file2
Input data is read from snap_file1 and snap_file2, which must be in snapshot(5NEMO) format. Default: none.
time1=time_range1
time2=time_range2
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=obs_expression
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.
diffpart=flag
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.
relative=flag
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.
nbins=num_bins
Number of equally-spaced bins to use for histogram. Default: 8.
xrange=x_axis_range
Range of values covered by histogram; of the form low:high. Default: 0.0:1.0.
xlabel=x_axis_label
Label for x-axis. Default is obs_expression.
nxticks=num_x_ticks
Number of equally-spaced tickmarks along x-axis. Default: 3.
ymax=max_y_value
If specified, use as max value on vertical axis; if not, program uses highest histogram bin to pic scaling. Default: none.
ylabel=y_axis_label
Label for y-axis. Default: N.
nyticks=num_y_ticks
Number of equally-spaced tickmarks along y-axis. Default: 3.
headline=
Verbiage at the top right of the graph. Default: none.

See Also

snapcmp(1NEMO) , snapdiff(1NEMO) , bodytrans(3NEMO) , snapshot(5NEMO)

Author

Joshua E. Barnes.


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