Synopsis
One-dimensional polynomial function of order 8.
Syntax
polynom1d
Description
The maximum order of the polynomial is 8. The default setting has all parameters frozen except for c0 , which means that the model acts as a constant.
Example
>>> create_model_component("polynom1d", "mdl")
>>> print(mdl)Create a component of the polynom1d 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.c6 frozen 0 -3.40282e+38 3.40282e+38 mdl.c7 frozen 0 -3.40282e+38 3.40282e+38 mdl.c8 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. |
| c6 | The amplitude of the (x-offset)^6 term. |
| c7 | The amplitude of the (x-offset)^7 term. |
| c8 | The amplitude of the (x-offset)^8 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 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.