BrokenPowerLaw1D¶
-
class
astropy.modeling.powerlaws.
BrokenPowerLaw1D
(amplitude=1, x_break=1, alpha_1=1, alpha_2=1, **kwargs)[source]¶ Bases:
astropy.modeling.Fittable1DModel
One dimensional power law model with a break.
- Parameters
amplitude : float
Model amplitude at the break point.
x_break : float
Break point.
alpha_1 : float
Power law index for x < x_break.
alpha_2 : float
Power law index for x > x_break.
See also
Notes
Model formula (with \(A\) for
amplitude
and \(\alpha_1\) foralpha_1
and \(\alpha_2\) foralpha_2
):\[\begin{split}f(x) = \left \{ \begin{array}{ll} A (x / x_{break}) ^ {-\alpha_1} & : x < x_{break} \\ A (x / x_{break}) ^ {-\alpha_2} & : x > x_{break} \\ \end{array} \right.\end{split}\]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_break, alpha_1, alpha_2)One dimensional broken power law model function
fit_deriv
(x, amplitude, x_break, alpha_1, …)One dimensional broken power law derivative with respect to parameters
Attributes Documentation
-
alpha_1
= Parameter('alpha_1', value=1.0)¶
-
alpha_2
= Parameter('alpha_2', value=1.0)¶
-
amplitude
= Parameter('amplitude', value=1.0)¶
-
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_break', 'alpha_1', 'alpha_2')¶
-
x_break
= Parameter('x_break', value=1.0)¶
Methods Documentation