CylindricalSymmetry

class gala.potential.potential.CylindricalSymmetry

Bases: PotentialSymmetry

Cylindrical (axisymmetric) symmetry for potentials with no azimuthal dependence.

This symmetry is appropriate for potentials that depend only on the cylindrical radius R = sqrt(x² + y²) and height z, but not on the azimuthal angle phi.

Examples

>>> import astropy.units as u
>>> import numpy as np
>>> from gala.potential import MiyamotoNagaiPotential
>>> pot = MiyamotoNagaiPotential(m=1e11*u.Msun, a=3*u.kpc, b=0.3*u.kpc)
>>> R = np.linspace(1, 15, 100) * u.kpc
>>> z = np.zeros_like(R)
>>> energy = pot.energy(R=R, z=z)
>>>
>>> # z can be omitted and defaults to zero
>>> energy = pot.energy(R=R)

Attributes Summary

coord_names

Methods Summary

to_cartesian(R[, z])	Convert cylindrical coordinates to Cartesian coordinates.
validate_coords(**coords)	Validate cylindrical coordinates.

Attributes Documentation

coord_names = ('R', 'z')

Methods Documentation

to_cartesian(R, z=None)

Convert cylindrical coordinates to Cartesian coordinates.

Parameters:

Rarray_like, Quantity

Cylindrical radius values. Can be scalar or array.

zarray_like, Quantity, optional

Height above/below the midplane. If not provided, defaults to zero with the same shape as R. Must have the same shape as R if provided.

Returns:

xyzQuantity or ndarray

Cartesian coordinates with shape (3, n_points). The x-component is set to R, y to 0, and z to the provided z values. Units are preserved if input has units.

Raises:

ValueError

If R and z have incompatible shapes.

validate_coords(**coords)

Validate cylindrical coordinates.

Parameters:

**coords

Coordinate keyword arguments. Must contain ‘R’, may contain ‘z’.

Raises:

ValueError

If R values are negative or invalid coordinates are provided.