# isochrone_to_aa¶

gala.dynamics.isochrone_to_aa(w, potential)[source]

Transform the input cartesian position and velocity to action-angle coordinates in the Isochrone potential. See Section 3.5.2 in Binney & Tremaine (2008), and be aware of the errata entry for Eq. 3.225.

This transformation is analytic and can be used as a “toy potential” in the Sanders & Binney (2014) formalism for computing action-angle coordinates in any potential.

Note

This function is included as a method of the IsochronePotential and it is recommended to call phase_space() instead.

Parameters: potential : gala.potential.IsochronePotential, dict An instance of the potential to use for computing the transformation to angle-action coordinates. Or, a dictionary of parameters used to define an gala.potential.IsochronePotential instance. actions : numpy.ndarray An array of actions computed from the input positions and velocities. angles : numpy.ndarray An array of angles computed from the input positions and velocities. freqs : numpy.ndarray An array of frequencies computed from the input positions and velocities.