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Institut für Astronomie und Astrophysik

Abteilung Astronomie

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fit Source code in cafe_fit.pro


           perform fit process of given model to data
           fit, [iterations][,/selected][,/quiet]
Input Parameters
           iterations - (optional) Number of iterations to perform
                         before query to prolong.
           quiet      - Do not show fit processing.
           selected   - Apply fit to selected data points only.
           nodata     - Take also models into account which are in
                        groups containing no data. May be usefull
                        when building complex models refering one to
           iterstop   - Stop when key 'q' pressed. Default true.
           All inputs/options may be set with the "set" command. The
           command prefix is "fit".
           The fit command performs the actual data fitting for given
           models. All groups containing (defined) data and a model
           are taken into account. The result are the best fit
           parameters with errors estimated from the inverted
           covariance matrix (the hessian).
           Fit results may be shown with "> show,result". The
           data/model distance is plotted with the plot model "res".
           During fitting parameter handling is as follows:
           - if a parameter is frozen (fixed flag = 1) the parameter
             will not be touched while fitting.
           - if a parameter is tied to another parameter this
             parameter will copy the latter parameter value (in case
             of expressions the value will be mapped with this
           - groups which contain a model but no valid data points
             are ignored. In case of the selected flag (s.a.) only
             selected data points are taken into account, i.e. if no
             data points are selected the group is ignored.
           - groups which contain valid data points but no model are
Side Effects
           Changes parameter values/errors in environment
           according fit result.
           Long lasting fit processes may be interrupted with "q".
               > model, "sin+lin", 2
               > fit
                 -> fit result
               > plot,data+model,res
Revision History
           $Id: cafe_fit.pro,v 1.25 2004/03/06 14:29:08 goehler Exp $

Last modified by pro2html on 2005 January 04 at 16:04 UTC

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Jörn Wilms (wilms@astro.uni-tuebingen.de)
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