RE: strange behavior of FillRandom

Hi,

you are filling the same histo all the time.
Add this
        TH1D *h[11];
        for(int k = 0; k <= NbSteps; k++) h[k] = (TH1D*)h2->Clone();
and then
                h[k]->FillRandom("f_gauss",3000);
                h[k]->Draw("E");

Cheers, Smbat
________________________________________
From: owner-roottalk_at_root.cern.ch [owner-roottalk_at_root.cern.ch] on behalf of Julien Bolmont [bolmont_at_in2p3.fr]
Sent: 31 March 2011 16:32
To: roottalk_at_lxroot01.cern.ch
Subject: [ROOT] strange behavior of FillRandom

Hi all,

I'm doing some experiments with FillRandom and I cannot explain what's happening.
I use a TF1 with the sum of 2 gaussian curves with different separations between them to generate a TH1.
If you run the macro below, you will see that the histogram looks ok at the beginning but that at the end, it doesn't reflect at all the shape of the TF1...

Is there a way to make this work ?

I use root 5.28/00 on Mac OS X 10.6.7.


Thanks a lot for your help !
Cheers,
Julien







test_bin() {

        int NbSteps = 10;
        float Peak1Pos = 2000;
        float Peak1Width = 400;
        float Peak2Pos_init = 4000;
        float Peak2Width = 400;

        TCanvas *c_lc = new TCanvas("c_lc", "c_lc", 1000, 500);
        c_lc->Divide(2, 1);

        // Binning 1 minute
        TH1D *h1 = new TH1D("test_h1", "test_h1", 100, 0, 6000);
        // Binning 30 seconds
        TH1D *h2 = new TH1D("test_h2", "test_h2", 200, 0, 6000);

        // Function for generation
        TF1 *f_gauss = new TF1("f_gauss","gaus(0)+gaus(3)", 0, 6000);
        f_gauss->SetNpx(1000);


        for(int k = 0; k <= NbSteps; k++) {

                float Peak2Pos = Peak2Pos_init - k * (Peak2Pos_init - Peak1Pos)/NbSteps;
                cout << "Separation (s) = " << Peak2Pos - Peak1Pos << endl;

                f_gauss->SetParameters(1, Peak1Pos, Peak1Width, 1, Peak2Pos, Peak2Width);

                c_lc->cd(1);
                f_gauss->Draw();

                c_lc->cd(2);
                h2->FillRandom("f_gauss",3000);
                h2->Draw("E");

                c_lc->Update();
                sleep(2);

        }
}