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)