freeze

sherpa.ui.freeze(*args)

Fix model parameters so they are not changed by a fit.

The arguments can be parameters or models, in which case all parameters of the model are frozen. If no arguments are given then nothing is changed.

Parameters

args (sequence of str or Parameter or Model) – The parameters or models to freeze.

See also

fit

Fit one or more data sets.

link

Link a parameter value to an associated value.

set_par

Set the value, limits, or behavior of a model parameter.

thaw

Allow model parameters to be varied during a fit.

unlink

Unlink a parameter value.

Notes

The thaw function can be used to reverse this setting, so that parameters can be varied in a fit.

Examples

Fix the FWHM parameter of the line model (in this case a gauss1d model) so that it will not be varied in the fit.

>>> set_source(const1d.bgnd + gauss1d.line)
>>> line.fwhm = 2.1
>>> freeze(line.fwhm)
>>> fit()

Freeze all parameters of the line model and then re-fit:

>>> freeze(line)
>>> fit()

Freeze the nh parameter of the gal model and the abund parameter of the src model:

>>> freeze(gal.nh, src.abund)