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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:
output file, will be in orbit(5NEMO) format [no default]
Initial value of position along x-axis [default: not used]
Initial value of position along y-axis [default: not used]
Initial value of velocity along x-axis [default: not used]
Initial value of velocity along y-axis [default: not used]
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].
The sign of lz will determine sense of rotation if only X or Y is given with etot.
name of file of the potential(5NEMO) descriptor, in case it is needed [default: none].
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].
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

See Also

stoo(1NEMO) , potlist(1NEMO) , orblist(1NEMO) , mkgalorbit(1NEMO) , mk2body(1NEMO) , potential(5NEMO)


Peter Teuben


~/src/orbit/io      mkorbit.c

Update History

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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