Disk2D

class astropy.modeling.functional_models.Disk2D(amplitude=1, x_0=0, y_0=0, R_0=1, **kwargs)

Bases: Fittable2DModel

Two dimensional radial symmetric Disk 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_0python:float

Radius of the disk

Other Parameters:

fixedpython:dict, optional

A dictionary {parameter_name: boolean} of parameters to not be varied during fitting. True means the parameter is held fixed. Alternatively the fixed property of a parameter may be used.

tiedpython:dict, optional

A dictionary {parameter_name: callable} of parameters which are linked to some other parameter. The dictionary values are callables providing the linking relationship. Alternatively the tied property of a parameter may be used.

boundspython:dict, optional

A dictionary {parameter_name: value} of lower and upper bounds of parameters. Keys are parameter names. Values are a list or a tuple of length 2 giving the desired range for the parameter. Alternatively, the min and max properties of a parameter may be used.

eqconspython:list, optional

A list of functions of length n such that eqcons[j](x0,*args) == 0.0 in a successfully optimized problem.

ineqconspython:list, optional

A list of functions of length n such that ieqcons[j](x0,*args) >= 0.0 is a successfully optimized problem.

See also

Box2D, TrapezoidDisk2D

Notes

Model formula:

\[\begin{split}f(r) = \left \{ \begin{array}{ll} A & : r \leq R_0 \\ 0 & : r > R_0 \end{array} \right.\end{split}\]

Attributes Summary

R_0
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.
x_0
y_0

Methods Summary

evaluate(x, y, amplitude, x_0, y_0, R_0)

Two dimensional Disk model function.

Attributes Documentation

R_0 = Parameter('R_0', value=1.0)

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

input_units

param_names = ('amplitude', 'x_0', 'y_0', 'R_0')

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.

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_0)

Two dimensional Disk model function.