Starlab version 4.4.1
    program created on Apr 27 2005 at 22:56:03
    source file     /home/steve/starlab/src/node/dyn/init/makepowerlaw.C

Construct a system of test particles drawn from a power-law mass
distribution, in virial equilibrium with the field due to that
distribution.  The mass distribution is of the form:

              M(r)  =  A r^x		(0 < x < 3)

except that r is modified to include a softening scale parameter:

                    r  -->  sqrt(r^2 + a^2)

The power-law particle distribution is created between some minimum
and maximum radii.  The inner radius is for numerical convenience, to
limit the number of stars on very tight orbits.  In addition, we allow
the possibility that the power-law potential is cut off within some
radius b and that there a point mass at the center.  The default mass
for the central point is the power-law mass within the cutoff.  The
point-mass potential is softened to avoid numerical problems.  If b is
nonzero, a is set to zero.

We assume that x > 0.  Particle parameters will be chosen so that
the total mass of the N-body system is 1, independent of the actual
mass of the background distribution.  For now, we are interested only
in test particles.  The particles are currently always drawn from the
power-law distribution, even within the cutoff radius.

The output snapshot will have the external field already enabled, and
will contain a flag to disable internal interactions.

Usage:  makepowerlaw [OPTIONS]

Options:
             -A    specify the coefficient A [1]
             -a/R  specify scale [1]
             -b    cutoff radius [0]
             -c    add a comment to the output snapshot [false]
             -C    output data in 'col' format [no]
             -d    make orbits disk-like within the cutoff [isotropic]
             -e    softening parameter [b/100]
             -i    number the particles sequentially [don't number]
             -l    minimum radius of the N-body system [0.1]
             -m/M  central mass [mass at cutoff]
             -n    specify number of particles [no default]
             -o    echo value of random seed [don't echo]
             -u    maximum radius of the N-body system [10]
             -s    specify random seed [random from system clock]
             -x    specify exponent [1]

Written by Steve McMillan.

Report bugs to starlab (at) sns.ias.edu.