Polynomial

class sherpa.astro.optical.Polynomial(name='polynomial')

Bases: sherpa.models.model.ArithmeticModel

Polynomial model of order 5.

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

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.

See also

Powerlaw

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.

Attributes Summary

thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Summary

apply(outer, \*otherargs, \*\*otherkwargs)
calc(p, x[, xhi])
get_center()
guess(dep, \*args, \*\*kwargs)	Set an initial guess for the parameter values.
reset()
set_center(\*args, \*\*kwargs)
startup()
teardown()

Attributes Documentation

thawedparhardmaxes

thawedparhardmins

thawedparmaxes

thawedparmins

thawedpars

Methods Documentation

apply(outer, *otherargs, **otherkwargs)

calc(p, x, xhi=None, **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.

reset()

set_center(*args, **kwargs)

startup()

teardown()