Tomasz Motylewski wrote: > > On Wed, 2 Sep 1998, Rene Brun wrote: > > > By default, Root creates a TMinuit object with 25 parameters. > > If you need more parameters, simply, do > > new TMinuit(55); > > How it differs from: > gMinuit = new TMinuit(55); > ? > No differences. the gMinuit pointer is automatically set by teh TMinuit constructor. > I have another question: what to do, if I want to fix (not optimize at all) > some parameters in TGraph::Fit ? I have quite good starting values for them. > Before I run TGraph::Fit, I may not use gMinuit->mnfixp and then > gMinuit->mnfree (or may I?). After I run TGraph::Fit all my parameters are > changed. Did you try the "B" option (Bound parameters). With this option, you must specify the limits for your parameters. To freeze one parameter, simply set the lower limit= the upper limit. > > I would suggest to add some "I" - init only option to ::Fit() - it would > perform everything without calling gMinuit->mnmigr() and printing statistics. > Then I have the gMinuit ready to run, but I can fine tune some parameters and > run it then. > This option could be added, but I do not understand what you want to do with TGraph::Fit in this case. Rene Brun
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