Re: Problem fitting histos

Hi,

Try with:

     TH1D *histo = new TH1D("histo"); //<------ I don't put bin and range because

The 'name' is required for the use by TTree::Draw.

Philippe.

On 1/25/12 11:48 AM, perfetto_at_na.infn.it wrote:
> Hi All,
>
> I don't be able to fitting and save some variables of a tree that I put in
> a histo.
> The following the part of my code that should do this... But when I run it:
>
> .L Fit.C
> fit_peak()
>
> I got the following result:
> <TCanvas::MakeDefCanvas>: created default TCanvas with name c1
> Warning in<Fit>: Fit data is empty
> 0
> Warning in<Fit>: Fit data is empty
> 0
> Warning in<Fit>: Fit data is empty
> 0
> Warning in<Fit>: Fit data is empty
> 0
>
> and ROOT open an empty canvas.
> Is there anyone can help me ?
>
> I use ROOT 5.26/00 on Scientific Linux 5
>
> Thanks in advance
> Francesco.
>
> #include<iostream>
> #include<fstream>
> #include<iomanip>
> #include<TH1>
>
> void fit_peak() {
>
> ofstream out;
> ...
> TFile *_file0 = TFile::Open("/data/singlepe/Run000470.root");
>
> TTree *tv__tree = (TTree *) gROOT->FindObject("Events");
>
> Double_t res_fit;
> TF1 *f = new TF1("f","gaus");
>
> for (Int_t i = 0; i< 4; i++) {
> TH1D *histo = new TH1D(); //<------ I don't put bin and range because
> I do not know in
> what
> range
> the
> histo
> lives.
>
> tv__tree->Draw( Form("-channels[%d].regions[0].integral>> histo", i)
> );
>
> histo->Fit(f);
>
> res_fit = f->GetParameter(i);
>
>
> out.open("result_fit_from_to.txt", ios::out | ios::app);
>
> out<< setw(8)<< setprecision(5)<< f->GetParameter(1);
> out<< setw(8)<< setprecision(5)<< f->GetParameter(2);
> out<< setw(8)<< setprecision(5)<< f->GetParameter(3);
> out<< endl;
>
> out.close();
> histo->Delete();
> }
> ....
> ....
> }
>
>
>
>
Received on Wed Jan 25 2012 - 18:56:45 CET