galpy.potential.scf_compute_coeffs_spherical_nbody

This function is the equivalent to galpy.potential.scf_compute_coeffs_spherical but computing the coefficients based on an N-body representation of the density.

Note: This function computes Acos and Asin as defined in Hernquist & Ostriker (1992), except that we multiply Acos by 2 such that the density from Galpy’s Hernquist Potential corresponds to \(Acos = \delta_{0n}\delta_{0l}\delta_{0m}\).

Further note that this function is a specification of galpy.potential.scf_compute_coeffs_nbody where \(Acos_{nlm} = 0\) at \(l\neq0\)

galpy.potential.scf_compute_coeffs_spherical_nbody(pos, N, mass=1.0, a=1.0)[source]

Numerically compute the expansion coefficients for a spherical expansion for a given $N$-body set of points

Parameters:

  • pos (numpy.ndarray) – Positions of particles in rectangular coordinates with shape [3,n]

  • N (int) – Size of the Nth dimension of the expansion coefficients

  • mass (float or numpy.ndarray, optional) – Mass of particles (scalar or array with size n), by default 1.0

  • a (float, optional) – Parameter used to scale the radius, by default 1.0

Returns:

Expansion coefficients for density dens that can be given to SCFPotential.__init__

Return type:

tuple

Notes

  • 2020-11-18 - Written - Morgan Bennett (UofT)

  • 2021-02-22 - Sped-up - Bovy (UofT)