Beta2D¶
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class
sherpa.astro.models.
Beta2D
(name='beta2d')[source]¶ Bases:
sherpa.models.model.RegriddableModel2D
Two-dimensional beta model function.
The beta model is a Lorentz model with a varying power law.
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r0
¶ The core radius.
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xpos
¶ The center of the model on the x0 axis.
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ypos
¶ The center of the model on the x1 axis.
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ellip
¶ The ellipticity of the model.
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theta
¶ The angle of the major axis. It is in radians, measured counter-clockwise from the X0 axis (i.e. the line X1=0).
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ampl
¶ The amplitude refers to the maximum peak of the model.
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alpha
¶ This parameter controls the slope of the profile at large radii.
See also
Beta1D
,DeVaucouleurs2D
,HubbleReynolds
,Lorentz2D
,Sersic2D
Notes
The functional form of the model for points is:
f(x0,x1) = ampl * (1 + r(x0,x1)^2)^(-alpha) r(x0,x1)^2 = xoff(x0,x1)^2 * (1-ellip)^2 + yoff(x0,x1)^2 ------------------------------------------- r0^2 * (1-ellip)^2 xoff(x0,x1) = (x0 - xpos) * cos(theta) + (x1 - ypos) * sin(theta) yoff(x0,x1) = (x1 - ypos) * cos(theta) - (x0 - xpos) * sin(theta)
The grid version is evaluated by adaptive multidimensional integration scheme on hypercubes using cubature rules, based on code from HIntLib ([1]) and GSL ([2]).
References
[1] HIntLib - High-dimensional Integration Library http://mint.sbg.ac.at/HIntLib/ [2] GSL - GNU Scientific Library http://www.gnu.org/software/gsl/ Attributes Summary
thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars
Methods Summary
apply
(outer, *otherargs, **otherkwargs)calc
(*args, **kwargs)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
(xpos, ypos, *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)¶
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calc
(*args, **kwargs)[source]¶ 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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guess
(dep, *args, **kwargs)[source]¶ 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)¶
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reset
()¶
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startup
()¶ Called before a model may be evaluated multiple times.
See also
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teardown
()¶ Called after a model may be evaluated multiple times.
See also
setup()
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