PowerLaw1D¶
-
class
astropy.modeling.powerlaws.
PowerLaw1D
(amplitude=1, x_0=1, alpha=1, **kwargs)[source]¶ Bases:
astropy.modeling.Fittable1DModel
One dimensional power law model.
- Parameters
- amplitudefloat
Model amplitude at the reference point
- x_0float
Reference point
- alphafloat
Power law index
- Other Parameters
- fixeda dict, optional
A dictionary
{parameter_name: boolean}
of parameters to not be varied during fitting. True means the parameter is held fixed. Alternatively thefixed
property of a parameter may be used.- tieddict, 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 thetied
property of a parameter may be used.- boundsdict, 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, themin
andmax
properties of a parameter may be used.- eqconslist, optional
A list of functions of length
n
such thateqcons[j](x0,*args) == 0.0
in a successfully optimized problem.- ineqconslist, optional
A list of functions of length
n
such thatieqcons[j](x0,*args) >= 0.0
is a successfully optimized problem.
Notes
Model formula (with \(A\) for
amplitude
and \(\alpha\) foralpha
):\[f(x) = A (x / x_0) ^ {-\alpha}\]Attributes Summary
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).Methods Summary
evaluate
(x, amplitude, x_0, alpha)One dimensional power law model function
fit_deriv
(x, amplitude, x_0, alpha)One dimensional power law derivative with respect to parameters
Attributes Documentation
-
alpha
= Parameter('alpha', value=1.0)¶
-
amplitude
= Parameter('amplitude', value=1.0)¶
-
input_units
¶
-
param_names
= ('amplitude', 'x_0', 'alpha')¶
-
x_0
= Parameter('x_0', value=1.0)¶
Methods Documentation