galpy.potential.evaluatezforces(Pot, R, z, phi=None, t=0.0, v=None)[source]

Evaluate the vertical force at a given position due to a potential, force or a list of potentials/forces.

  • Pot (Potential, DissipativeForce or list of Potential or DissipativeForce instances) – A potential, dissipative force or a list of such objects.

  • R (float or Quantity) – Cylindrical Galactocentric distance.

  • z (float or Quantity) – Distance above the plane.

  • phi (float or Quantity, optional) – Azimuth (default: None).

  • t (float or Quantity, optional) – Time (default: 0.0).

  • v (numpy.ndarray or Quantity, optional) – Current velocity in cylindrical coordinates. Required when including dissipative forces. Default is None.


The vertical force F_z(R,z,phi,t).

Return type:

float or Quantity


  • 2010-04-16 - Written - Bovy (NYU)

  • 2018-03-16 - Added velocity input for dissipative forces - Bovy (UofT)