# RedshiftScaleFactor¶

class astropy.modeling.functional_models.RedshiftScaleFactor(z=0, **kwargs)[source]

One dimensional redshift scale factor model.

Parameters
zfloat

Redshift value.

Notes

Model formula:

$f(x) = x (1 + z)$

Attributes Summary

 param_names Names of the parameters that describe models of this type. z

Methods Summary

 evaluate(x, z) One dimensional RedshiftScaleFactor model function fit_deriv(x, z) One dimensional RedshiftScaleFactor model derivative

Attributes Documentation

param_names = ('z',)

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.

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

Methods Documentation

static evaluate(x, z)[source]

One dimensional RedshiftScaleFactor model function

static fit_deriv(x, z)[source]

One dimensional RedshiftScaleFactor model derivative