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Name

firstn - von Hoerners first N-body code

Synopsis

firstn < firstn.in

Description

firstn currently only integrates an example internally-generated Plummer sphere.

Input

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 -

Performance

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

Caveats

This is a code meant to be historic and educational, and should most certainly not be used for any serious work.

Author

S. von Hoerner (original), Sverre Aarseth (21st century adaptation)
Z.f.Astrophys. 50, 184, 1960 (1960ZA.....50..184V)
Files
~/usr/aarseth/firstn    original

See Also

nbody0(1NEMO)

History


dec-2000    version from Aarseth                       PJT
9-mar-04    man page written,                 PJT


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