Last modified: December 2018

URL: http://cxc.harvard.edu/sherpa/ahelp/powerlaw.html
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AHELP for CIAO 4.11 Sherpa v1

powerlaw

Context: models

Synopsis

Power-law model.

Syntax

powerlaw

Description

It is for use when the independent axis is in Angstroms.


Example

>>> create_model_component("powerlaw", "mdl")
>>> print(mdl)

Create a component of the powerlaw model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.refer    frozen         5000  1.17549e-38  3.40282e+38  angstroms
   mdl.ampl     thawed            1  1.17549e-38  3.40282e+38  angstroms
   mdl.index    thawed         -0.5          -10           10           

ATTRIBUTES

The attributes for this object are:

refer

The reference point at which the amplitude is defined, with units of Angstroms.

ampl

The amplitude at the reference point.

index

The index for the power law.

Notes

The functional form of the model for points is:

f(x) = ampl * (x / refer)^index

and for integrated data sets the low-edge of the grid is used.


Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

models
brokenpowerlaw, polynomial