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mkorbit - make an orbit with initial conditions
mkorbit out=orbit
[parameter=value]
mkorbit will generate an orbit by either given
it the exact inititial coordinates in phase space, or specifying an energy
and leaving out one of the velocities (the standard way to generate initial
conditions for a surface of section plot). In the last case an external
potential needs to be given.
Orbits can also be created from snapshots,
by using stoo(1NEMO)
.
Note: currently the z,vz coordinates are set to zero,
generating effectively 2D orbits.
The following parameters are
recognized in any order if the keyword is also given:
- out=out-file
- output
file, will be in orbit(5NEMO)
format [no default]
- x=x-position
- Initial value
of position along x-axis [default: not used]
- y=y-position
- Initial value of
position along y-axis [default: not used]
- vx=x-velocity
- Initial value of
velocity along x-axis [default: not used]
- vy=y-velocity
- Initial value of
velocity along y-axis [default: not used]
- etot=energy
- Energy of the orbit.
If no value is given, the program assumes that all phase space coordinates
will be used. If a value for the energy is given, one of the phase space
velocities may be left out, and will be calculated. In this case the potential
where the orbit is calculated in, must also be given, see next 3 parameters
[default: not used].
- lz=
- The sign of lz will determine sense of rotation
if only X or Y is given with etot.
- potname=name
- name of file of the potential(5NEMO)
descriptor, in case it is needed [default: none].
- potpars=par-list
- List
of parameters to the potential descriptor. The first parameter MUST be the
pattern speed in the x-y plane, (although rotating frames of reference are
not supported in all programs). The remaining parameters are used by the
inipotential() routine in the potential descriptor. [default: none - let
them be defined by routine itself].
- potfile=name
- name of an optional datafile
to the potential descriptor. This might be an N-body snapshot or table of
spline fit coefficients etc. [default: none].
To fully specify an
orbit without the need for a potential
% mkorbit orb1.dat 1 0 0 0 1 0
one can specifiy a potential, which simplifies using it in orbint(1NEMO)
as the potential parameters do not need to be specified again:
% mkorbit orb2.dat 1 0 0 0 1 0 potname=plummer potpars=0,2.0,0.3
or specify a launch point on the X or Y axis, and an energy, but here the
potential is required:
% mkorbit orb3.dat x=1 e=-1.4 potname=plummer potpars=0,2.0,0.3
stoo(1NEMO)
, potlist(1NEMO)
, orblist(1NEMO)
, mkgalorbit(1NEMO)
,
mk2body(1NEMO)
, potential(5NEMO)
Peter Teuben
~/src/orbit/io mkorbit.c
xx-jul-87 V1.0: Created: PJT
4-May-88 V2.1: keywords e,potential etc. implemented PJT
2-Jun-88 V2.2: new filestruct, no code change PJT
2-Mar-92 V2.3: new NEMO 2.x PJT
10-dec-2019 V4.4: implemented PHI/ACC storage; simplified orbit launching PJT
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