Polynom1D

class sherpa.models.basic.Polynom1D(name='polynom1d')

Bases: sherpa.models.model.RegriddableModel1D

One-dimensional polynomial function of order 8.

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.

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.

See also

PowLaw1D, Polynom2D

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.

Attributes Summary

thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Summary

apply(outer, *otherargs, **otherkwargs)
calc(pars, xlo, *args, **kwargs)
get_center()
guess(dep, *args, **kwargs)	Set an initial guess for the parameter values.
regrid(*arrays)
reset()
set_center(*args, **kwargs)
startup()	Called before a model may be evaluated multiple times.
teardown()	Called after a model may be evaluated multiple times.

Attributes Documentation

thawedparhardmaxes

thawedparhardmins

thawedparmaxes

thawedparmins

thawedpars

Methods Documentation

apply(outer, *otherargs, **otherkwargs)

calc(pars, xlo, *args, **kwargs)

get_center()

guess(dep, *args, **kwargs)

Set an initial guess for the parameter values.

Attempt to set the parameter values, and ranges, for the model to match the data values. This is intended as a rough guess, so it is expected that the model is only evaluated a small number of times, if at all.

regrid(*arrays)

reset()

set_center(*args, **kwargs)

startup()

Called before a model may be evaluated multiple times.

See also

teardown()

teardown()

Called after a model may be evaluated multiple times.

See also

setup()