Last modified: December 2018

URL: http://cxc.harvard.edu/sherpa/ahelp/disk2d.html
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AHELP for CIAO 4.11 Sherpa v1

disk2d

Context: models

Synopsis

Two-dimensional uniform disk model.

Syntax

disk2d

Description

Two-dimensional step function model consisting of a uniform intensity disk.


Example

>>> create_model_component("disk2d", "mdl")
>>> print(mdl)

Create a component of the disk2d model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.xpos     thawed            0 -3.40282e+38  3.40282e+38           
   mdl.ypos     thawed            0 -3.40282e+38  3.40282e+38           
   mdl.ampl     thawed            1 -3.40282e+38  3.40282e+38           
   mdl.r0       thawed            1            0  3.40282e+38           

ATTRIBUTES

The attributes for this object are:

xpos

The center of the disk on the x0 axis.

ypos

The center of the disk on the x1 axis.

ampl

The amplitude of the signal within the disk.

r0

The radius of the disk.

Notes

The functional form of the model for points is:

f(x0,x1) = ampl  if (x0 - xpos)^2 + (x1 - ypos)^2 <= r0^2

         = 0     otherwise

For grids, the x0lo,x1lo values are used in the above equation.

This model was provided by Christoph Deil.


Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

models
shell2d