Saving Fitted Histograms to a Root File

[amytee]

Hey,

I am opening a root file, getting a histogram and then fitting it. I then want to save the histogram to a new root file. However, when I save the histogram it seems to only save the global fit, rather than the global, background and signal fits.

Here is my script below:

 #include <TH2.h>
 #include <TStyle.h>
 #include <TCanvas.h>
#include <TChain.h>


//Declare a user defined functions for fitting:

 // Quadratic background function
 Double_t background(Double_t *x, Double_t *par) {
   return par[0] + par[1]*x[0] + par[2]*x[0]*x[0];
 }


 //Gaussian

 Double_t Gaussian1(Double_t *x, Double_t *par){
   return par[0]/sqrt(2*M_PI)/(par[2])*(par[3])*exp(-0.5*pow(((x[0]-par[1])/par[2]),2)); //  p3 is    p0  ///par 3 is new!!! //Par[2] here is the bin width

}


 //Sum of Background and Guassian

 Double_t FitFunction(Double_t *x, Double_t *par){
   return background(x,par) + Gaussian1(x,&par[3]);
 }


 void Fits()
 { //OPENING BRACE

   //#################################################################
  //            OPEN UP ROOT FILE AND OBTAIN HISTOGRAM
   //#################################################################


    TFile *file = new TFile("My_Saved_Plots_user_jwalder.root", "READ")

    file->ls();

     TH1D *h1  = (TH1D*)file->Get("One_J_One_P");


     //#################################################################
     //                         FITTING
     //#################################################################


    h1->Rebin(3);


    //Fit Function for h1

     TF1 *FitFcn = new TF1("FitFcn", FitFunction, 2700.0, 3500.0, 7);
     FitFcn->SetNpx(500);
     FitFcn->SetLineWidth(4);
     FitFcn->SetLineColor(kMagenta);


     // second try: set start values for some parameters
     FitFcn->SetParameter(5,50.0); // width   //index 5 of the parameters  
     FitFcn->SetParameter(4, 3100.0 );   // peak   //index 4 of params
     FitFcn->SetParameter(3, 19000);   //some other normalization
     FitFcn->FixParameter(6, h1->GetBinWidth(1)); // bin width
    FitFcn->SetParameter(0, 200); //index 0, constant term in background
    FitFcn->SetParameter(1, -0.05); //index 1, coeff. x term in background
    FitFcn->SetParameter(2, 0); //index 2,  coeff. x^2 term in background

     FitFcn->FixParameter(2,0);
    //FitFcn->FixParameter(4,3100.0);
    h1->Fit("FitFcn"," " , "ep");
    h1->Fit("FitFcn"," " , "ep");
   cout << h1->GetBinWidth(1) <<  " Bin Width" << std::endl; //MeV

    // improve the picture:
   TF1 *backFcn = new TF1("backFcn",background,2700.0, 3500.0, 3);
   backFcn->SetLineColor(kRed);
  TF1 *signalFcn = new TF1("signalFcn",Gaussian1, 2700.0 ,3500.0 , 4);
  signalFcn->SetLineColor(kBlue);
  signalFcn->SetNpx(500);
  Double_t par[7];

   // writes the fit results into the par array
   FitFcn->GetParameters(par);

    backFcn->SetParameters(par);
   backFcn->Draw("same");

   signalFcn->SetParameters(&par[3]);
   signalFcn->Draw("same");


   // draw the legend
   TLegend *legend=new TLegend(0.10,0.70,0.38,0.90);
   legend->SetTextFont(72);
    legend->SetTextSize(0.04);
    legend->AddEntry(h1,"Data","lpe");
   legend->AddEntry(backFcn,"Background fit","l");
  legend->AddEntry(signalFcn,"Signal fit","l");
  legend->AddEntry(FitFcn,"Global Fit","l");
  legend->Draw();

    gStyle->SetOptStat(1111111);
    gStyle->SetOptFit(1111);

     TFile *file2 = new TFile("Fit_Plots.root", "RECREATE");
     file2->cd();


      h1->Write();

  }// CLOSING BRACE

[amvargash]

file2->Write() Perhaps?