# Plummer1D¶

class astropy.modeling.physical_models.Plummer1D(mass=1.0, r_plum=1.0, **kwargs)[source]

One dimensional Plummer density profile model.

Parameters
massfloat

Total mass of cluster.

r_plumfloat

Scale parameter which sets the size of the cluster core.

Notes

Model formula:

$\rho(r)=\frac{3M}{4\pi a^3}(1+\frac{r^2}{a^2})^{-5/2}$

References

1

Attributes Summary

 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). mass param_names Names of the parameters that describe models of this type. r_plum

Methods Summary

 evaluate(x, mass, r_plum) Evaluate plummer density profile model. fit_deriv(x, mass, r_plum) Plummer1D model derivatives.

Attributes Documentation

input_units
mass = Parameter('mass', value=1.0)
param_names = ('mass', 'r_plum')

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_plum = Parameter('r_plum', value=1.0)

Methods Documentation

static evaluate(x, mass, r_plum)[source]

Evaluate plummer density profile model.

static fit_deriv(x, mass, r_plum)[source]

Plummer1D model derivatives.