Re: Problem fitting histos

Hi Francesco,

On Wed, 25 Jan 2012, 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

You don't need a bin and range, but you do need a name and title. Try this:

TH1D *histo = new TH1D(Form("histo%1d",i),"Title",100,1,0); // the bin start is larger than bin end -> this will make binning automatic  tv__tree->Draw( Form("-channels[%d].regions[0].integral >> histo%1d", i,i)

Should work...

Cheers

        Eduard

> 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 - 18:57:53 CET