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hackcode3, hackcode3_qp - hierarchical N-body code (3)
hackcode3 is fully based on hackcode1, except
it allows you to fiddle with the potential in various ways. They all have
as a result that the total energy of the system is (generally) not conserved.
The keyword nrigid allows you to fix the first nrigid particles in space.
The keywords potname, potpars and potfile allow you to add a "static" background
potential in the potential(5NEMO)
The following parameters
are recognized; they may be given in any order.
a restart is specified, values must be given for ALL legal parameters which
do not take default values.
- If given, initial
conditions will be read from in-file in snapshot format. At most one of in,
restart, or continue may be specified.
- If given, results are
written to out-file in snapshot format. Note as of version 1.4 only the non-rigid
particles are output.
- If given, the system state will
be read from state-file. New values are accepted for the following parameters:
out, save, eps, tol, options, fcells, tstop, freqout, minor_freqout, and
debug. At most one of in, restart, or continue may be specified.
- If given, the system state will be read from state-file. New values are accepted
for the following parameters: out, save, and debug. At most one of in, restart,
or continue may be specified.
- If given, the system state
will be saved in state-file after each timestep.
of bodies for test data, generated only if none of in, restart, or continue
are specified. Default is 128.
- Random number seed used in
generating initial conditions. Default is 123.
- If true,
generate centrally concentrated test system. Default is false.
- Inverse time-step, to be used with a leap-frog integrator. Default is 32.0
(32 steps per unit time).
- Force softening parameter. Default
- Opening-angle tolerence parameter. Default is 1.0.
- Ratio of cells to bodies, used when allocating cells. Default is 0.75.
- Miscellaneous control options, specified as a comma-separated list of keywords.
Currently recognized keywords are: reset_time: when reading initial data,
set tnow to zero; new_tout: when restarting, set new output times; mass,
phi, acc: output mass, potential, acceleration data with major data outputs.
- The first nrigid particles are taken as rigid. [default: 0]
- Time to stop integration in N-body model units. Default is
- Frequency of major N-body data outputs. Default is 4.0
(4 frames per unit time).
- Frequency of minor diagnostic
outputs. If this frequency is not a simple fraction of freq (see above),
the program can waiste significant amounts of time. Default is 32.0 (32 diagnostic
measurements per unit time).
- Descriptor name for potential(5)
- Parameters for potential(5)
. The first
one is normally reserverd for pattern speed, and is now set to 0.0. If a
name for the potential is given, and no parameters are given here, intrinsic
defaults are used. [default: none].
- Optional additional filename
. For historic reasons the parameter list in potpars can
only contain numbers. If for any reason it also needs a character string
(often a filename associated with the potential), the potfile parameter
is used. [default: none].
- Debugging switch; generates lots
of output. Default is false.
For relatively large values of nrigid the code
is inefficient, because it still calculates the forces for all rigid particles
on every timestep. It would only be necessary when diagnostics are computed.
The nrigid algorithm used will only work when the force does not depend
on the velocities of the particles.
26-Jan-90 V1.2 nrigid added PJT
2-apr-90 V1.2a etot bug removed PJT
8-may-92 formally added to NEMO PJT
21-dec-2012 V1.4 only non-rigid particles output PJT
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