From: Rene BRUN <rene.brun_at_cern.ch>

Date: Wed, 26 Jan 2005 11:57:28 +0100

Date: Wed, 26 Jan 2005 11:57:28 +0100

Hi Boris,

The current version of TSpectrum::Search looks for peaks in the full histogram range. In your case teh first bin of your histogram is around 650000 while the other visible peaks are around 100. With your version of ROOT simply call h1->SetBinContent(1,0) and Search will find the 6 peaks.

In the CVS version, I have added support for a bin range such that you do not need the SetBinContent(1,0).

Rene Brun

Boris Skorodumov wrote:

*> Dear rooters,*

*> *

*> I was trying to change example program peaks.C to force it working with *

*> real spectrum (for example, detector calbration, Gaus fitter should work *

*> with it). I was trying to use the next procedure to find peaks:*

*> .....*

*> TSpectrum *s = new TSpectrum(npeaks);*

*> Int_t nfound = s->Search(h2,1,"");*

*> printf("Found %d candidate peaks to fit\n",nfound);*

*> .....*

*> but i always getting 0. to tell you the truth, i do not know what the *

*> problem, maybe with resolutions of the peaks, maybe with sigma settings, *

*> maybe something more.*

*> *

*> I attached source file and test.root with test histogram.*

*> Thank you for the help,*

*> Boris.*

*> *

*> *

*> ------------------------------------------------------------------------*

*> *

*> #include "TCanvas.h"*

*> #include "TH1.h"*

*> #include "TF1.h"*

*> #include "TRandom.h"*

*> #include "TSpectrum.h"*

*> #include "TVirtualFitter.h"*

*> *

*> Int_t npeaks = 30;*

*> *

*> Double_t fpeaks(Double_t *x, Double_t *par) {*

*> // Double_t result = par[0] + par[1]*x[0];*

*> Double_t result =0.0;*

*> *

*> for (Int_t p=0;p<npeaks;p++) {*

*> Double_t norm = par[3*p];*

*> Double_t mean = par[3*p+1];*

*> Double_t sigma = par[3*p+2];*

*> result += norm*TMath::Gaus(x[0],mean,sigma);*

*> }*

*> return result;*

*> }*

*> *

*> *

*> void d1_fit(Int_t np=10) {*

*> *

*> npeaks = np;*

*> *

*> Double_t par[3000];*

*> *

*> TFile *hfile = gROOT->FindObject("test.root"); if (hfile) hfile->Close();*

*> hfile = new TFile("test.root","READ","Test Calibration");*

*> *

*> TCanvas *c1 = new TCanvas("c1","c1",10,10,700,700);*

*> c1->Divide(1,2);*

*> c1->cd(1);*

*> h1->GetXaxis()->SetRange(50,500);*

*> h1->Draw(); // TH1F *h = new TH1F("h","test",1000,0,2000);*

*> *

*> TH1F *h2 = (TH1F*)h1->Clone("h2");*

*> *

*> // cout << npeaks; *

*> TSpectrum *s = new TSpectrum(npeaks);*

*> // s->SetResolution(0.1);*

*> Int_t nfound = s->Search(h2,1,"");*

*> *

*> printf("Found %d candidate peaks to fit\n",nfound);*

*> npeaks = nfound;*

*> *

*> c1->Update();*

*> c1->cd(2);*

*> *

*> printf("Now fitting: Be patient\n");*

*> *

*> *

*> *

*> TF1 *fit = new TF1("fit",fpeaks,0,2000,3*npeaks);*

*> TVirtualFitter::Fitter(h2,10+3*npeaks); *

*> fit->SetParameters(par);*

*> fit->SetNpx(2000);*

*> h2->Fit("fit"); *

*> }*

*> // t->Draw()*

*> // TH1F *h1 = new TH1F("h1","h1 title",2000,0,2000);("epsd >> h1"); *

*> // h1->GetXaxis()->SetRange(50,500) ; h1->Draw();*

Received on Wed Jan 26 2005 - 11:57:34 MET

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