histogram display in peak search

Dear rooters,

Could someone teach me

1. why the attached script (named 'peakSearchTest.C'), which try to find candidate of peaks from TH1F "hpx" in "hsimple.root" using TSpectrum::Search(), DISPLAYS the histogram when run as an unnamed script (.x peakSearchTest.C), whereas it does not when run as a named one (by invoking peakSearchTest() after loading the script (or `.x peakSearchTest.C`), of course after uncommenting the function name in the script and commenting out the first curly brace.)?

   In the latter, only an empty canvas is displayed...    (though a candidate is successfully found)

2. whether it is possible to seach peaks using TSpectrum::Search()

   without displaying any canvas/histogram (or control    its display) in interactive root sessions (i.e. w/o    -b option) or not?

   Even though the histogram is not explicitly drawn,    the attached script (when run as unnamed one) displays    it.

Thanks in advance.

Yours,
Kazuyoshi

--
Kazuyoshi Furutaka
furutaka _dot_ kazuyoshi _at_ jaea _dot_ go _dot_ jp




#if !defined(__CINT__)

#  include "TCanvas.h"

#  include "TH1.h"

#  include "TFile.h"

#  include "TSpectrum.h"

#endif


{
//void peakSearchTest() {

  // create a canvas
  TCanvas *c1 = new TCanvas("c1","c1",10,10,800,500);

  // read and draw a histogram from a file
  TFile f("hsimple.root");
  TH1F *h = (TH1F*)f.Get("hpx");
  //h->Draw();

  // search a peak, maxpositions=1, resolution=1(default)
  TSpectrum *s = new TSpectrum(2);
  // in histogram 'h', sigma=2, options="", thresh.=0.10
  Int_t npfound = s->Search(h,2,"",0.10);
  if ( npfound > 0 ) {
    Float_t *xpeaks = s->GetPositionX();
    for ( Int_t np=0 ; np < npfound ; np++ ) {
      Float_t xp = *(xpeaks+np);
      Int_t    bin    = h->GetXaxis()->FindBin(xp);
      printf("Found a candidate of peak at %d channel.\n", bin);
    }
  }
}