Polynomial¶
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class
sherpa.astro.optical.
Polynomial
(name='polynomial')[source] [edit on github]¶ Bases:
sherpa.models.model.RegriddableModel1D
Polynomial model of order 5.
This model can be used with any one-dimensional data set since there are no units on the parameters.
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c0
¶ The constant term.
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c1
¶ The amplitude of the (x-offset) term.
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c2
¶ The amplitude of the (x-offset)^2 term.
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c3
¶ The amplitude of the (x-offset)^3 term.
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c4
¶ The amplitude of the (x-offset)^4 term.
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c5
¶ The amplitude of the (x-offset)^5 term.
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offset
¶ There is a degeneracy between
c0
andoffset
, so it is recommended that at least one of these remains frozen.
See also
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])Evaluate the model on a grid. 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
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thawedparhardmaxes
¶
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thawedparhardmins
¶
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thawedparmaxes
¶
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thawedparmins
¶
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thawedpars
¶
Methods Documentation
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apply
(outer, *otherargs, **otherkwargs) [edit on github]¶
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calc
(p, x, xhi=None, **kwargs)[source] [edit on github]¶ Evaluate the model on a grid.
Parameters: - p (sequence of numbers) – The parameter values to use. The order matches the
pars
field. - *args – The model grid. The values can be scalar or arrays, and the number depends on the dimensionality of the model and whether it is being evaluated over an integrated grid or at a point (or points).
- p (sequence of numbers) – The parameter values to use. The order matches the
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get_center
() [edit on github]¶
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guess
(dep, *args, **kwargs) [edit on github]¶ 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.
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regrid
(*arrays) [edit on github]¶
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reset
() [edit on github]¶
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set_center
(*args, **kwargs) [edit on github]¶
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startup
() [edit on github]¶ Called before a model may be evaluated multiple times.
See also
-
teardown
() [edit on github]¶ Called after a model may be evaluated multiple times.
See also
setup()
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