// root.cern.ch/root/htmldoc/guides/spectrum/Spectrum.html#dimensional-spectra
// root.cern.ch/doc/master/Background__width_8C.html

// See: M.Morhac et al., Nucl. Instr. Meth. A 401, 113 (1997)

// Example to illustrate the influence of the clipping window width on the
//
// Authors: Miroslav Morhac, Olivier Couet


void Background_width () 
{
  Int_t i;
  Int_t nbins = 1024;
  Double_t xmin    = 0;
  Double_t xmax    = nbins;
  Double_t* source = new Double_t [nbins];
  gROOT->ForceStyle ();

  TFile* f    = new TFile ("TSpectrum.root");
  TH1F* hdata = (TH1F*) f->Get ("back1");
  hdata->GetXaxis()->SetRange (1, nbins);
  hdata->SetTitle ("Influence of clipping window width on the estimated background");
  hdata->SetLineColor (kBlack);
  hdata->Draw ("L");

  TSpectrum *Analyser1dim = new TSpectrum ();


  /** Case for numberIterations = 4 (numberIterations = max width of clipping window) **/

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);

  // Estimate the Background

  Analyser1dim->Background (
          source, nbins, 4, TSpectrum::kBackDecreasingWindow,
          TSpectrum::kBackOrder2, kFALSE,
          TSpectrum::kBackSmoothing3, kFALSE );

/*
    const char* TSpectrum::Background (
     Double_t* spectrum,      pointer to the vector of source spectrum
     Int_t ssize,	      length of the spectrum vector
     Int_t numberIterations,  maximal width of clipping window,
     Int_t direction,	      direction of change of clipping window. 
			      Possible values: kBackIncreasingWindow, kBackDecreasingWindow
     Int_t filterOrder,	      order of clipping filter. Possible values:
			      kBackOrder2, kBackOrder4, kBackOrder6, kBackOrder8
     bool  smoothing,	      logical variable whether the smoothing operation in the
			      estimation of background will be included. (0/1)
     Int_t smoothWindow,      width of smoothing window. Possible values: 
			      kBackSmoothing3, kBackSmoothing5, ..., kBackSmoothing15
     bool  compton	      whether the estimation of Compton edge will be included. (0/1)
   ) 

   See: root.cern.ch/doc/v608/classTSpectrum.html#a7830480612d1ee301964e6c79319f444
*/


  TH1F* hbkgnd1 = new TH1F ("hbkgnd1", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) hbkgnd1->SetBinContent (i+1, source[i]);
  hbkgnd1->SetLineColor (kRed);
  hbkgnd1->Draw ("SAME L");


  /** Case for numberIterations = 6 (numberIterations = max width of clipping window) **/

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);

  Analyser1dim->Background (
          source, nbins, 6, TSpectrum::kBackDecreasingWindow,
          TSpectrum::kBackOrder2, kFALSE,
          TSpectrum::kBackSmoothing3, kFALSE);

  TH1F* hbkgnd2 = new TH1F ("hbkgnd2", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) hbkgnd2->SetBinContent (i+1, source[i]);
  hbkgnd2->SetLineColor (kGreen);
  hbkgnd2->Draw( "SAME L");


  /** Case for numberIterations = 8 (numberIterations = max width of clipping window) **/

  for (i = 0; i < nbins; i++) source[i] = hdata->GetBinContent (i+1);

  Analyser1dim->Background (
          source, nbins, 8, TSpectrum::kBackDecreasingWindow,
          TSpectrum::kBackOrder2, kFALSE,
          TSpectrum::kBackSmoothing3, kFALSE);

  TH1F* hbkgnd3 = new TH1F ("hbkgnd3", "", nbins, xmin, xmax);
  for (i = 0; i < nbins; i++) hbkgnd3->SetBinContent (i+1, source[i]);
  hbkgnd3->SetLineColor (kBlue);
  hbkgnd3->Draw ("SAME L");

  gStyle->SetOptStat (0);
  
  TLegend* legend = new TLegend (0.1, 0.7, 0.48, 0.9);
  legend->AddEntry (hdata  , "Data"     , "l");
  legend->AddEntry (hbkgnd1, "Width = 4", "l");
  legend->AddEntry (hbkgnd2, "Width = 6", "l");
  legend->AddEntry (hbkgnd3, "Width = 8", "l");
  legend->Draw();
}