Last modified: December 2018

URL: http://cxc.harvard.edu/sherpa/ahelp/delta2d.html
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AHELP for CIAO 4.11 Sherpa v1

delta2d

Context: models

Synopsis

Two-dimensional delta function.

Syntax

delta2d

Description

The delta function model is only non-zero at a single point (or pixel for integrated grids).


Example

>>> create_model_component("delta2d", "mdl")
>>> print(mdl)

Create a component of the delta2d 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           

ATTRIBUTES

The attributes for this object are:

xpos

The coordinate of the signal on the x0 axis.

ypos

The coordinate of the signal on the x1 axis.

ampl

The amplitude.

Notes

The functional form of the model for points is:

f(x0, x1) = ampl if x0 == xpos and x1 == ypos
     = 0         otherwise

and for an integrated grid it is:

f(x0lo, x1lo, x0hi, x1hi) = ampl if x0lo <= xpos <= x0hi
                                    x1lo <= ypos <= x1hi
                          = 0    otherwise

This behavior is different to how the amplitude is handled in other models, such as Const2D .


Bugs

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

See Also

models
box2d, const2d, delta1d