Gaussian function for modeling emission.
It is for use when the independent axis is in Angstroms.
>>> create_model_component("emissiongaussian", "mdl") >>> print(mdl)
Create a component of the emissiongaussian model and display its default parameters. The output is:
mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.fwhm thawed 100 1.17549e-38 3.40282e+38 km/s mdl.pos frozen 5000 1.17549e-38 3.40282e+38 angstroms mdl.flux thawed 1 -3.40282e+38 3.40282e+38 mdl.skew frozen 1 1.17549e-38 3.40282e+38
The attributes for this object are:
The full-width half-maximum of the model in km/s.
The center of the gaussian, in Angstroms.
The normalisation of the gaussian.
The skew of the gaussian.
The model is only evaluated for points that lie within limit sigma of pos. It is a hidden parameter, with a default value of 4.
The functional form of the model for points is:
f(x) = flux * exp(-0.5 * d(x)^2) / s2 if skew = 1 = 2 * flux * exp(-0.5 * d2(x)^2) / (s2 * (1 + skew)) otherwise d(x) = (x - pos) / s d2(x) = d(x) if x <= pos = d(x) / skew otherwise s2 = 2.50662828 * s s = pos * fwhm / (2.9979e5 * 2.354820044)
and for integrated data sets the low-edge of the grid is used.
The calculation is only done for those points that are in the range:
|x - pos| < limit * sigma
Outside this range the model is set to 0.
See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.