galpy.orbit.Orbit.e

Orbit.e(analytic=False, pot=None, **kwargs)[source]

NAME:

e

PURPOSE:

calculate the eccentricity, either numerically from the numerical orbit integration or using analytical means

INPUT:

analytic(= False) compute this analytically

pot - potential to use for analytical calculation

For 3D orbits different approximations for analytic=True are available (see the EccZmaxRperiRap method of actionAngle modules):

type= (‘staeckel’) type of actionAngle module to use

  1. ‘adiabatic’: assuming motion splits into R and z
  2. ‘staeckel’: assuming motion splits into u and v of prolate spheroidal coordinate system, exact for Staeckel potentials (incl. all spherical potentials)
  3. ‘spherical’: for spherical potentials, exact

+actionAngle module setup kwargs for the corresponding actionAngle modules (actionAngleAdiabatic, actionAngleStaeckel, and actionAngleSpherical)

OUTPUT:

eccentricity [*input_shape]

HISTORY:

2019-02-25 - Written - Bovy (UofT)