Re: [ROOT] 2D Fit autoscaling problem

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Mar 18 2003 - 21:35:35 MET


Steven,

Could you send me (not to the list please), what I requested
in my first mail: a working script that I can use
to understand your problem and a few explanations?

Rene Brun

On Tue, 18 Mar 
2003, steven staelens wrote:

> root Version 3.05/01 on Intel Linux RH 7.1
> 
> 
>         Hi Rene,
> 
> Rene Brun wrote:
> 
> > Hi Steven,
> >
> > For making a TGraph out of a TTree, see section:
> >   "How to obtain more info from TTree::Draw"
> > in the documentation of TTree::Draw at:
> >    http://root.cern.ch/root/htmldoc/TTree.html
> >
> > Concerning your question about making a TGraph out of a TF2,
> > I do not understand what you mean. There is a mismatch with dimensions.
> >
> 
> I also concluded this fact, which rules out the possibility of using
> multigraphs to avoid the autoscaling problem, right ?  I still haven't solved
> the problem yet (...although I'm trying).  Do you perhaps have another
> suggestion to solve my particular 2dfit problem (a typical example is in the
> 2dfit.gif file of a former mail I've posted), in particular to avoid the
> autoscaling ?
> 
> many thanks for your first reply,
> 
> best regards,
> 
> Steven
> 
> >
> > Rene Brun
> >
> >  steven staelens wrote:
> > >
> > > root Version 3.05/01 on Intel Linux RH 7.1
> > >
> > >         Hi ,
> > >
> > > In addition to a former mail I narrowed my problem down to the
> > > following:
> > >
> > > I have fitted a twodimensional function to a twodimensional histogram as
> > > it should following ROOT user guide lines.  The fit seems to be OK, but
> > > to be really sure I have to plot it on top of the lego plot of the
> > > histogram.  When I do so, the maximum value of my histogram is set equal
> > > to the maximum of my 2D fit.  In my case, this is absolutely not
> > > wanted.  I've read on the ROOT digest that this is normal and that it
> > > can be solved by using a MultiGraph.
> > >
> > > Being a ROOT newbie however I don't know how to switch the drawings of
> > > my TF2 and of my TH2F into a TGraph.  I've tried in the following
> > > pathetic way:
> > >
> > > TGraph *f2D = new TGraph()
> > > h2D->Draw(">>t1")
> > >
> > > but I realize this is not the way it should be.
> > >
> > > Can somebody perhaps help me out by giving an example on how to change a
> > > 2D histogram drawing into a TGraph object and the same question for a
> > > twodimensional function.  When this is solved I can then easily do:
> > >
> > > TMultigraph *mg = new TMultiGraph()
> > > mg->Add(gr1)
> > > mg->Add(gr2)
> > > mg->Draw()
> > >
> > > and my problem will be solved.
> > >
> > > 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
> 



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