polynomial

Context: models

Synopsis

Polynomial model of order 5.

Syntax

polynomial

Description

This model can be used with any one-dimensional data set since there are no units on the parameters.

Example

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

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

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.c0       thawed            1 -3.40282e+38  3.40282e+38           
   mdl.c1       frozen            0 -3.40282e+38  3.40282e+38           
   mdl.c2       frozen            0 -3.40282e+38  3.40282e+38           
   mdl.c3       frozen            0 -3.40282e+38  3.40282e+38           
   mdl.c4       frozen            0 -3.40282e+38  3.40282e+38           
   mdl.c5       frozen            0 -3.40282e+38  3.40282e+38           
   mdl.offset   frozen            0 -3.40282e+38  3.40282e+38

ATTRIBUTES

The attributes for this object are:

Attribute	Definition
c0	The constant term.
c1	The amplitude of the (x-offset) term.
c2	The amplitude of the (x-offset)^2 term.
c3	The amplitude of the (x-offset)^3 term.
c4	The amplitude of the (x-offset)^4 term.
c5	The amplitude of the (x-offset)^5 term.
offset	There is a degeneracy between c0 and offset , so it is recommended that at least one of these remains frozen.

Notes

The functional form of the model for points is:

f(x) = sum_(i=0)^(i=8) c_i * (x - offset)^i

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.