# Polynom2D¶

class sherpa.models.basic.Polynom2D(name='polynom2d')[source] [edit on github]

Two-dimensional polynomial function.

The maximum order of the polynomial is 2.

c

The constant term.

cy1

The coefficient for the x1 term.

cy2

The coefficient for the x1^2 term.

cx1

The coefficient for the x0 term.

cx1y1

The coefficient for the x0 x1 term.

cx1y2

The coefficient for the x0 x1^2 term.

cx2

The coefficient for the x0^2 term.

cx2y1

The coefficient for the x0^2 x1 term.

cx2y2

The coefficient for the x0^2 x1^2 term.

Notes

The functional form of the model for points is:

f(x,x1) = c + cx1 * x0 + cx2 * x0^2 +
cy1 * x1 + cy2 * x1^2 +
cx1y1 * x0 * x1 +
cx1y2 * x0 * x1^2 +
cx2y1 * x0^2 * x1 +
cx2y2 * x0^2 * x1^2


and for an integrated grid it is the integral of this over the bin.

Attributes Summary

Methods Summary

 apply(outer, *otherargs, **otherkwargs) calc(*args, **kwargs) Evaluate the model on a grid. guess(dep, *args, **kwargs) Set an initial guess for the parameter values. regrid(*args, **kwargs) set_center(*args, **kwargs) startup([cache]) Called before a model may be evaluated multiple times. Called after a model may be evaluated multiple times.

Attributes Documentation

ndim = 2
thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars

Methods Documentation

apply(outer, *otherargs, **otherkwargs) [edit on github]
calc(*args, **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).

get_center() [edit on github]
guess(dep, *args, **kwargs)[source] [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.

regrid(*args, **kwargs) [edit on github]
reset() [edit on github]
set_center(*args, **kwargs) [edit on github]
startup(cache=False) [edit on github]

Called before a model may be evaluated multiple times.

Parameters

cache (bool, optional) – Should a cache be used when evaluating the models.

teardown() [edit on github]

Called after a model may be evaluated multiple times.

setup()