# DF (galpy.df)¶

galpy.df contains tools for dealing with distribution functions of stars in galaxies. It mainly contains a number of classes that define different types of distribution function, but galpy.df.jeans also has some tools for solving the Jeans equations for equilibrium systems.

## Two-dimensional, axisymmetric disk distribution functions¶

Distribution function for orbits in the plane of a galactic disk.

## Two-dimensional, non-axisymmetric disk distribution functions¶

Distribution function for orbits in the plane of a galactic disk in non-axisymmetric potentials. These are calculated using the technique of Dehnen 2000, where the DF at the current time is obtained as the evolution of an initially-axisymmetric DF at time to in the non-axisymmetric potential until the current time.

## Three-dimensional disk distribution functions¶

Distribution functions for orbits in galactic disks, including the vertical motion for stars reaching large heights above the plane. Currently only the quasi-isothermal DF.

## The distribution function of a gap in a tidal stream¶

From Sanders, Bovy, & Erkal 2015; see Modeling gaps in streams. Implemented as a subclass of streamdf. No full implementation is available currently, but the model can be set up and sampled as in the above paper.