# Ring2D¶

class astropy.modeling.functional_models.Ring2D(amplitude=1, x_0=0, y_0=0, r_in=1, width=1, r_out=None, **kwargs)[source] [edit on github]

Two dimensional radial symmetric Ring model.

Parameters: amplitude : float Value of the disk function x_0 : float x position center of the disk y_0 : float y position center of the disk r_in : float Inner radius of the ring width : float Width of the ring. r_out : float Outer Radius of the ring. Can be specified instead of width.

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 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
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).

Model sub-classes can also use function annotations in evaluate to indicate valid input units, in which case this property should not be overridden since it will return the input units based on the annotations.

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

Methods Documentation

static evaluate(x, y, amplitude, x_0, y_0, r_in, width)[source] [edit on github]

Two dimensional Ring model function.