pseudovoigt1d

Context: models

Synopsis

A weighted sum of a Gaussian and Lorentzian distribution.

Syntax

pseudovoigt1d

Description

Unlike the Voigt1D model, which is a convolution between a Gaussian and Lorentz distribution, this approximates the Voigt profile with a linear combination of the two profiles [1] . It is often used in spectroscopy.

Example

>>> create_model_component("pseudovoigt1d", "mdl")
>>> print(mdl)

Create a component of the pseudovoigt1d model and display its default parameters. The output is:

mdl
   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.frac     thawed          0.5            0            1           
   mdl.fwhm     thawed           10  1.17549e-38  3.40282e+38           
   mdl.pos      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:

Attribute	Definition
frac	The fraction of the model composed of the Gaussian profile (0 to 1).
fwhm	The full-width half-maximum (FWHM) of each component.
pos	The center of the profile.
ampl	The amplitude of the profile.

Notes

The model can be written as:

f(x) = frac * g(x) + (1 - frac) * l(x)

where g(x) and l(x) are NormGauss1D and Lorentz1D models with the fwhm, pos, and ampl values taken from this model.

References

[1] https://en.wikipedia.org/wiki/Voigt_profile#Pseudo-Voigt_approximation

Changes in CIAO

Added in CIAO 4.13

The pseudovoigt1d and voigt1d models were added in CIAO 4.13 and replace the absorptionvoigt and emissionvoigt models.

Bugs

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