Re: [ROOT] TH2F - TF2

From: Rene Brun (Rene.Brun@cern.ch)
Date: Mon Jun 30 2003 - 10:34:30 MEST


Michael,

I will investigate this problem once I will be back to CERN on Thursday.
Meanwhile, could you send me a running script showing the problem?
I have some suspicion about your  h2D->FindBin(x,y).

Rene Brun

Michael Wiesmann wrote:
> 
> Hallihallo Rooters!
> 
> I have a TH2F h2D, I check a bin content a la
> h2D->GetBinContent( h2D->FindBin(x,y)); //returns 17
> 
> I have a TF2 fitFcn,I check a value a la
> fitFcn->Eval(x,y) // returns 12.5
> //same with TF1::EvalPar(x,parameter)
> 
> Now I do
> h2D->Add(fitFcn,-1.0);
> h2D->GetBinContent( h2D->FindBin(x,y)); /returns 7.76
> 
> Naively I would expect 17-12.5 to be 4.5. Obviously I am too naive for
> this problem.
> 
> I tried to use TH1F::Eval(TF1,"A"), which gave me (17+12.5=) 26.2,
> which is at least consistent.
> 
> Sounds like TH2F::Add(TF1) uses another set of parameters.
> 
> Any hint what I missunderstood?
> 
> Michael
> 
> PS: I am using  root 3.03/09  on RH Linux 7.2



This archive was generated by hypermail 2b29 : Thu Jan 01 2004 - 17:50:12 MET