Hi Steven, see: http://root.cern.ch/root/roottalk/RoottalkRules.html Rene Brun steven staelens wrote: > > Hi guys, > > I'm using ROOT for the analysis of my nuclear medicine Monte Carlo > simulations results. Therefore I want to fit a twodimensional function > to a 2D histogram. I therefore use the following code: > > #include "TF2.h" > #include "TH2.h" > > void fit2d(){ > TFile b("t4.root"); > > Singles->Draw("PosZ:PosX>>hnew(18,0,180,20,-200,200)"); > > TF2 *f2e = new TF2("f2e", > "([0]*(y+201))/([1]*(x^2+(y+201)^2))",-0.5,180.5,-201,201) ; > > f2e->SetParameters(1,1) ; > > hnew->Fit("f2e") ; > > hnew->Draw("LEGO") ; > > f2e->Draw("LEGO same"); > } > > The result I get is not satisfactory however as I see that the maxima of > the histogram and the fit are put equal. This is of course not the most > appropriate fit as can be seen from the attached gif. The wireframe > plot is the data while the filled lego plot is the fit. > > In fact I was wondering how I could change the criteria in TH2F::Fit to > optimalize my 2D fit, as I have the impression now that it is mainly > penalizing the maximum deviation. > > Thanks in advance, > > best regards, > > Steven > > S. Staelens > Ghent University > ELIS / Medisip > Proeftuinstraat 86 > B-9000 Gent > tel. 0032 9 264 66 28 > fax. 0032 9 264 66 18 > email: Steven.Staelens@rug.ac.be > > -------------------------------------------------------------------------------- > Name: 2dfit.gif > 2dfit.gif Type: GIF Image (image/gif) > Encoding: base64
This archive was generated by hypermail 2b29 : Thu Jan 01 2004 - 17:50:10 MET