Last modified: December 2023

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/bpl1d.html
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AHELP for CIAO 4.16 Sherpa

bpl1d

Context: models

Synopsis

One-dimensional broken power-law function.

Syntax

bpl1d

Example

>>> create_model_component("bpl1d", "mdl")
>>> print(mdl)

Create a component of the bpl1d model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.gamma1   thawed            0          -10           10           
   mdl.gamma2   thawed            0          -10           10           
   mdl.eb       thawed          100            0         1000           
   mdl.ref      frozen            1 -3.40282e+38  3.40282e+38           
   mdl.ampl     thawed            1        1e-20  3.40282e+38           

ATTRIBUTES

The attributes for this object are:

Attribute Definition
gamma1 The slope of the power law below the break point.
gamma2 The slope of the power law above the break point.
eb The position of the break point.
ref The reference position for the amplitude.
ampl The amplitude, defined with respect to the reference position.

Notes

The functional form of the model for points is:

 f(x) = ampl * (x / ref)^(-gamma1)   x <= eb

      = ampl' * (x / ref)^(-gamma2)  otherwise

ampl' = ampl (eb / ref)^(gamma2 - gamma1)

and for an integrated grid it is the integral of this over the bin.


Bugs

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