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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: modeling


Freeze model parameters, so they do not vary during a fit.


freeze([parameter], [[parameters]])


Given one or more model parameters, freeze each model parameter at its current value. The frozen parameters are not varied during a fit. (If an argument is a model, then all the model parameters of that model are frozen.)

  • parameter(s) - model parameters to freeze for the fit

The freeze function must be given at least one argument. That argument must be a model or a model parameter. The function can be given an indefinite number of models and/or model parameters as arguments. If a model is an argument, all the parameters of that model are frozen at their current values.

To unfreeze model parameter values and allow them to vary, the command thaw ("ahelp thaw") is used.

Example 1

sherpa> freeze(g.ampl)

The model parameter "ampl" of model "g" is frozen at its current value.

Example 2

sherpa> freeze(g.ampl, g.fwhm)

Both model parameters "ampl" and "fwhm" of model "g" are frozen at their current values.

Example 3

sherpa> freeze(g)

All model parameters specified in model "g" are frozen at their current values.


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

See Also

guess, link, paramprompt, set_par, thaw, unlink

Last modified: December 2010
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