Ring2D

class astropy.modeling.functional_models.Ring2D(amplitude=1, x_0=0, y_0=0, r_in=None, width=None, r_out=None, **kwargs)

Bases: Fittable2DModel

Two dimensional radial symmetric Ring model.

Parameters:

amplitudepython:float

Value of the disk function

x_0python:float

x position center of the disk

y_0python:float

y position center of the disk

r_inpython:float

Inner radius of the ring

widthpython:float

Width of the ring.

r_outpython:float

Outer Radius of the ring. Can be specified instead of width.

See also

Disk2D, TrapezoidDisk2D

Notes

Model formula:

\[\begin{split}f(r) = \left \{ \begin{array}{ll} A & : r_{in} \leq r \leq r_{out} \\ 0 & : \text{else} \end{array} \right.\end{split}\]

Where \(r_{out} = r_{in} + r_{width}\).

Attributes Summary

amplitude
input_units	This property is used to indicate what units or sets of units the evaluate method expects, and returns a dictionary mapping inputs to units (or None if any units are accepted).
param_names	Names of the parameters that describe models of this type.
r_in
width
x_0
y_0

Methods Summary

evaluate(x, y, amplitude, x_0, y_0, r_in, width)

Two dimensional Ring model function.

Attributes Documentation

amplitude = Parameter('amplitude', value=1.0)

input_units

param_names = ('amplitude', 'x_0', 'y_0', 'r_in', 'width')

Names of the parameters that describe models of this type.

The parameters in this tuple are in the same order they should be passed in when initializing a model of a specific type. Some types of models, such as polynomial models, have a different number of parameters depending on some other property of the model, such as the degree.

When defining a custom model class the value of this attribute is automatically set by the Parameter attributes defined in the class body.

r_in = Parameter('r_in', value=1.0)

width = Parameter('width', value=1.0)

x_0 = Parameter('x_0', value=0.0)

y_0 = Parameter('y_0', value=0.0)

Methods Documentation

static evaluate(x, y, amplitude, x_0, y_0, r_in, width)

Two dimensional Ring model function.