Problem Fitting .root file histogram

Newbie
1

Hi,
I am trying to run a script for a new root file with a histogram, but for some reason, calling the fit function for this new file doesn’t even fit the data, whereas with a previous file it did. Below is the script to generate the problem, and attached is the root file. Can someone help figure out how to fix this fit problem?

double FiveParam2015TEV_plus_Gauss(double *x, double *har){double Ecm=13.;double fCenterOfMassEnergy = Ecm;bool fUseWindowExclusion = false;double y = x[0] / fCenterOfMassEnergy;double ff1=har[0]*TMath::Power((1.0-y),har[1]);double ff2=TMath::Power(y,(har[2]+har[3]*log(y)+har[4]*log(y)*log(y)));double ff=((ff1*ff2));return ff;}
string xdir="";
    string figdir="figs/";
    char nameX[]="m_{jjl} [TeV]";
    char nameY[]="Events / TeV";
    double Ymin=0.9;
    double Ymax=1000000000.0-100000.0;
    double YRMIN=-4.999;
    double YRMAX=4.999;
    double Xmin=400.0;
    double Xmax=10000.0;
    Xmin=Xmin*0.001;
    Xmax=Xmax*0.001;
    double NN=0.0;
    gROOT->SetStyle("Plain");
    TCanvas* c1 = new TCanvas("c","BPRE",10,10,600,600);
    c1->Divide(1,1,0.005,0.005);
    c1->SetTickx();
    c1->SetTicky();
    c1->SetTitle("");
    c1->SetLineWidth(3);
    c1->SetBottomMargin(0.1);
    c1->SetTopMargin(0.05);
    c1->SetRightMargin(0.01);
    c1->SetFillColor(0);
    TPad* pad1 = new TPad("pad1","pad1",0,0.3,1,0.97);
    pad1->SetBottomMargin(0);
    pad1->SetLeftMargin(0.13);
    pad1->SetRightMargin(0.04);
    pad1->SetTopMargin(0.02);
    pad1->Draw();
    pad1->cd();
    pad1->SetLogy(1);
    pad1->SetLogx(1);
    TH1F *h=pad1->DrawFrame(Xmin,Ymin,Xmax,Ymax);
    TAxis *ay = h->GetYaxis();
    ay->SetLabelFont(42);
    ay->SetLabelSize(0.05);
    ay->SetTitleSize(0.06);
    ay->SetNdivisions(505);
    ay->SetTitle(nameY);
    TAxis *ax=h->GetXaxis();
    ax->SetTitle(nameX);
    ax->SetTitleOffset(1.18);
    ay->SetTitleOffset(0.8);
    ax->SetLabelFont(42);
    ay->SetLabelFont(42);
    ax->SetLabelSize(0.12);
    ax->SetTitleSize(0.14);
    ax->Draw("same");
    ay->Draw("same");
    string dir = xdir;
    TFile *ff = new TFile("mjjl_smooth_mc.root");
    ff->ls();
char name[] = "jjlmass";
    TH1* hh = static_cast<TH1*>(ff->Get(name));
    TH1* hhorg = static_cast<TH1*>(hh->Clone());
TFile TFdata("mjjl_smooth_mc.root");
    cout << TFdata.GetName()<< endl;
    TH1* bids= static_cast<TH1*>(TFdata.Get("bins_m"));
    TH1* bins= static_cast<TH1*>(TFdata.Get("bins_m"));
    bids->Scale(1.0/92.0);
    cout << "Bool: "<< hh->Divide(bids) << endl;
    hh->SetTitle("");
    hh->SetStats(0);
    hh->SetLineWidth(2);
    hh->Print("All");
    hh->SetAxisRange(Ymin,Ymax,"y"); //0.00001
    hh->SetAxisRange(Xmin,Xmax,"x");
hh->SetMarkerColor( 3 );
    hh->SetMarkerStyle( 20 );
    hh->SetMarkerSize( 0.8 );
 double MyMinX=Xmin;
    double MyMaxX=Xmax;
    hh->Draw("pe");
  TF1 ball("5p+gauss",FiveParam2015TEV_plus_Gauss,MyMinX,MyMaxX,5);
    ball.SetNpx(200);
    ball.SetLineColor(4);
    ball.SetLineStyle(1);
    ball.SetLineWidth(2);
ball.SetParameter(0,6.05059e+04);
ball.SetParameter(1,1.32594e+01);
ball.SetParameter(2,5.85506e-01);
ball.SetParameter(3,1.78302e+00);
ball.SetParameter(4,2.83882e-01);
auto fitr=hh->Fit(&ball,"SL","");fitr->Print();

mjjl_smooth_mc.root (6.7 KB)

ROOT Version: 6.23/01

2

Hi,
is this what you are getting?

Warning in <Fit>: Abnormal termination of minimization.
 FCN=-nan FROM MIGRAD    STATUS=CALL LIMIT   1664 CALLS        1665 TOTAL
                     EDM=-nan    STRATEGY= 1      NO ERROR MATRIX       
  EXT PARAMETER               CURRENT GUESS       STEP         FIRST   
  NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE 
   1  p0                  -nan   1.81518e+04          -nan          -nan
   2  p1                  -nan   3.97782e+00          -nan          -nan
   3  p2                  -nan   1.75652e-01          -nan          -nan
   4  p3                  -nan   5.34906e-01          -nan          -nan
   5  p4                  -nan   8.51646e-02          -nan          -nan
                               ERR DEF= 0.5

****************************************
         Invalid FitResult  (status = 4 )
****************************************
Minimizer is Minuit / Migrad
MinFCN                    =         -nan
Chi2                      =          inf
NDf                       =          160
NCalls                    =         1665
p0                        =         -nan   +/-   18151.8     
p1                        =         -nan   +/-   3.97782     
p2                        =         -nan   +/-   0.175652    
p3                        =         -nan   +/-   0.534906    
p4                        =         -nan   +/-   0.0851646

Cheers,
Enrico

1 Like
3

Is it possible that FiveParam2015TEV_plus_Gauss evaluates to very large, very small or inf/nan values so the minimizer has a hard time?

EDIT: yes, in fact putting a std::cout << ff << '\n' I can see it produces nans, e.g. because of a division by zero.

1 Like
4

Yes, this is exactly the problem I am facing. Do you know how to fix it?

5

Ok, so the problem was that this was in GeV, not TeV, so I was fitting out of range, now I fixed it.

double FiveParam2015TEV_plus_Gauss(double *x, double *har){double Ecm=13000.;double fCenterOfMassEnergy = Ecm;bool fUseWindowExclusion = false;double y = x[0] / fCenterOfMassEnergy;double ff1=har[0]*TMath::Power((1.0-y),har[1]);double ff2=TMath::Power(y,(har[2]+har[3]*log(y)+har[4]*log(y)*log(y)));double ff=((ff1*ff2));return ff;}
string xdir="";
    string figdir="figs/";
    char nameX[]="m_{jjl} [GeV]";
    char nameY[]="Events / GeV";
    double Ymin=0.9;
    double Ymax=1000000000.0-100000.0;
    double YRMIN=-4.999;
    double YRMAX=4.999;
    double Xmin=400.0;
    double Xmax=10000.0;
    Xmin=Xmin;
    Xmax=Xmax;
    double NN=0.0;
    gROOT->SetStyle("Plain");
    TCanvas* c1 = new TCanvas("c","BPRE",10,10,600,600);
    c1->Divide(1,1,0.005,0.005);
    c1->SetTickx();
    c1->SetTicky();
    c1->SetTitle("");
    c1->SetLineWidth(3);
    c1->SetBottomMargin(0.1);
    c1->SetTopMargin(0.05);
    c1->SetRightMargin(0.01);
    c1->SetFillColor(0);
    TPad* pad1 = new TPad("pad1","pad1",0,0.3,1,0.97);
    pad1->SetBottomMargin(0);
    pad1->SetLeftMargin(0.13);
    pad1->SetRightMargin(0.04);
    pad1->SetTopMargin(0.02);
    pad1->Draw();
    pad1->cd();
    pad1->SetLogy(1);
    pad1->SetLogx(1);
    TH1F *h=pad1->DrawFrame(Xmin,Ymin,Xmax,Ymax);
    TAxis *ay = h->GetYaxis();
    ay->SetLabelFont(42);
    ay->SetLabelSize(0.05);
    ay->SetTitleSize(0.06);
    ay->SetNdivisions(505);
    ay->SetTitle(nameY);
    TAxis *ax=h->GetXaxis();
    ax->SetTitle(nameX);
    ax->SetTitleOffset(1.18);
    ay->SetTitleOffset(0.8);
    ax->SetLabelFont(42);
    ay->SetLabelFont(42);
    ax->SetLabelSize(0.12);
    ax->SetTitleSize(0.14);
    ax->Draw("same");
    ay->Draw("same");
    string dir = xdir;
    TFile *ff = new TFile("mjjl_smooth_mc.root");
    ff->ls();
char name[] = "jjlmass";
    TH1* hh = static_cast<TH1*>(ff->Get(name));
    TH1* hhorg = static_cast<TH1*>(hh->Clone());
TFile TFdata("mjjl_smooth_mc.root");
    cout << TFdata.GetName()<< endl;
    TH1* bids= static_cast<TH1*>(TFdata.Get("bins_m"));
    TH1* bins= static_cast<TH1*>(TFdata.Get("bins_m"));
    bids->Scale(1.0/92.0);
    cout << "Bool: "<< hh->Divide(bids) << endl;
    hh->SetTitle("");
    hh->SetStats(0);
    hh->SetLineWidth(2);
    hh->Print("All");
    hh->SetAxisRange(Ymin,Ymax,"y"); //0.00001
    hh->SetAxisRange(Xmin,Xmax,"x");
hh->SetMarkerColor( 3 );
    hh->SetMarkerStyle( 20 );
    hh->SetMarkerSize( 0.8 );
 double MyMinX=Xmin;
    double MyMaxX=Xmax;
    hh->Draw("pe");
  TF1 ball("5p+gauss",FiveParam2015TEV_plus_Gauss,MyMinX,MyMaxX,5);
    ball.SetNpx(200);
    ball.SetLineColor(4);
    ball.SetLineStyle(1);
    ball.SetLineWidth(2);
ball.SetParameter(0,6.05059e+04);
ball.SetParameter(1,1.32594e+01);
ball.SetParameter(2,5.85506e-01);
ball.SetParameter(3,1.78302e+00);
ball.SetParameter(4,2.83882e-01);
auto fitr=hh->Fit(&ball,"SL","");fitr->Print();
1 Like