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Overview of SMOOTH

Smooth can calculate several mean quantities for all particles in an N-Body simulation output file. The program produces a file for each type of output specified by the user. Example outputs are calculation of the density, mean velocity, mean speed, velocity dispersion, mach number, and phase density. These output files contain one "smoothed" quantity per particle. The output files produced by smooth are in the tipsy array format. This means that tipsy can color the particles of a simulation according to the particular smooth output produced, for example the density of every particle.

Smooth takes input files in the tipsy binary format. Simulations with periodic boundary conditions can also be handled by smooth by specifying the period in each dimension on the command line (see MAN page below). By default the program uses a symmetric spline smoothing kernel similar to that used in SPH calculations. This program has been designed to calculate these "smoothed" quantities very quickly, while using a minimal amount of memory.

Release 2.01 new features and changes

New features for release 2.01 is support for mark arrays to allow quick calculation of mean quantities on a subset of the particles. Also that annoying MAXFLOAT problem has been removed. Sorry, that was caused by using an old version of GCC while creating version 2.0 on one of our systems. Note: SUN cc compiler is not ANSI compliant and will cause a errors, use GCC on the SUN.

To obtain smooth, get the tar file from our Anonymous ftp-site at The relevant tar file is /pub/hpcc/smooth.2.01.tar.Z.

To build smooth,

zcat smooth.2.01.tar.Z | tar xfv -


This should build smooth on most systems.

See MAN page for help on using smooth.

Support for this software is now being hosted on SourceForge. For problems, questions and comments concerning this software, please go to the SourceForge Astrophysical N-body Tools site.

N-Body Shop
University of Washington
Box 351580
Seattle, WA  98195-1580
(206) 543-2888 voice, (206) 685-0403 FAX
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