Problem Fit several spectra

I am trying to make a fit of five spectra. I create a kind of array that will contain each espectrum with:

TH1 *h_hLcPt[5]

and then I fill them with

h_hLcPt[0] = new TH1F("h_hLcPt[0]","1 spectrum",125, 2.15, 2.65);

and so on for the rest 4 … Later I use a loop to access to every index, but fist as I want them in a canvas to see the five of them:

TCanvas *cx=new TCanvas("cx","hLcPt1,2,3,4,5 plot",600,900);

Int_t j;

Then the loop

    for (j=0;j<5;j++) {

And plot the spectra. So, now I acces to every index in a for a nested loop. I started with the j=0

if (j==0){
    par = fillArray(6);// Array for the parameters of the fit i.e  the sum of the functions
    //Fit function
    TF1 *fitFcn1 = new TF1("fitFcn1",fitFunction_GN_GNBkg,2.2,2.4,6);
    fitFcn1->SetParNames("Norm1","Mean1","Sigma1","Norm2","Mean2", "Sigma2"); 
    //As I want to see the bakgraund function (gauss normalized) 
    //and the signal function(gauss normalized) 
TF1 *backFcn1 = new TF1("backFcn1", GausBkg1,2.22,2.4,3);
    TF1 *signalFcn1 = new TF1("signalFcn1",gaussNFunction, 2.25,2.32,3);
    signalFcn1->SetLineColor(1); //kBlue//6 hot pink//5 yellow

    //And add it to the plot
}//Close j=0

Then I run the code and the result are the backgound a flat line over the x axis and the signal is a flat line at the level of the plot. BTW, the definition of the functions used are

  • Fit functions
Double_t gaussNFunction(Double_t *x,Double_t *par){
    return ( par[0]/(TMath::Sqrt(2.*TMath::Pi())*par[2]) )*TMath::Exp( 
    -(x[0]-par[1])*(x[0]-par[1])/(2.*par[2]*par[2]) );
//The same
Double_t GausBkg1(Double_t *x, Double_t *par) {
    return ( par[0]/(TMath::Sqrt(2.*TMath::Pi())*par[2]) )*TMath::Exp( 
    -(x[0]-par[1])*(x[0]-par[1])/(2.*par[2]*par[2]) );
    Double_t fitFunction_GN_GNBkg(Double_t *x, Double_t *par) {
    return gaussNFunction(x,par) - GausBkg1(x,&par[3])  ;

And the parameters

Double_t * fillArray(Int_t n) {
    // create a double array of length n, fill it with random numbers return a pointer to it
    Double_t *x = new Double_t[n];
    //TRandom generator(0);
    for(Int_t i=0; i<n; i++) x[i] = 0;/*generator.Rndm();*/
    return x;
   Double_t *par;// with *

I even used the fit panel to get the initial parameters for the fit. But does not work.

Can you explain how exactly your macro doesn’t work? If you could attach a complete reproducer, that would also help.

I have seen the problem I had. Sorry for the inconveniences and thanks for interest.

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