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firstn - von Hoerners first N-body code
firstn < firstn.in
firstn
currently only integrates an example internally-generated Plummer sphere.
The firstn.in input file contains 3 lines (See also nbody0(1NEMO)
).
N ETA EPS DELTAT TCRIT
ALPHAS BODY1 BODYN KZ5
Q, ISCALE
- N - number of particles.
- ETA - integration accuracy
- EPS - gravitational softening
(note vH used no softening)
- DELTAT - time interval of data output.
- TCRIT
- final integration time
- ALPHAS - slope of the IMF
- BODY1 - lower cutoff in
IMF
- BODYN - upper cutoff in IMF
- KZ5 - control parameter what kind of input
data are generated.
- Q - Initial virial ratio (1 meant 2T/W=1)
- ISCALE -
CPU
should scale as N^2. Here are some numbers from a
N cpu" cpu"
? p4/1600/gcc ifort
16 2.9 2.2 0.79
32 62.0 33.2 19.0
64 93.4 27.8 84.2
128 642.6 108.4 75.1
256 n/a 834.3 746.5
This is a code meant to be historic and educational, and should
most certainly not be used for any serious work.
S. von Hoerner (original),
Sverre Aarseth (21st century adaptation)
Z.f.Astrophys. 50, 184, 1960 (1960ZA.....50..184V)
Files
~/usr/aarseth/firstn original
nbody0(1NEMO)
dec-2000 version from Aarseth PJT
9-mar-04 man page written, PJT
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