#include "TFile.h"
#include "TCanvas.h"
#include "TStyle.h"
#include "TH1.h"
#include "TH2.h"
#include "TH3.h"
#include "TGaxis.h"
#include "TRandom.h"
#include "TLegend.h"
#include "TPaveStats.h"
#include "TGraph.h"
double FunFit(const double *x, const double *p) {
  double l = x[0];
  double a = p[0];
  double b = p[1];
  double c = p[2];
  y = (l/15+0.964)*(l/15+0.964)*a+2*(l/15+0.964)*(l*l*/15-0.36*l)*b+(l*l*/15-0.36*l)*(l*l*/15-0.36*l)*c;
  return y;
}

void grafico()
{
   
   char datagamma[200]= "D:/Datifit.txt";
   char dataout[200]="D:/graph.pdf";
   TCanvas *c36 = new TCanvas("c36","multigraph",1280,1024);
   
   
   //c36->SetLogx();
   //c36->SetLogy();
   float offx=1.1;
   float offy=1.5;
   float margr=0.08;
   float margl=0.12;
  gStyle->SetOptFit();
   gPad->SetLeftMargin(margl);
   gPad->SetRightMargin(margr);
   TMultiGraph *mg = new TMultiGraph();
   gStyle->SetOptStat("nemr"); // "nemr" or "neMR"
   gStyle->SetOptFit(112);
 
 TGraphErrors *gamma = new TGraphErrors(datagamma,"%lg %lg");
    gamma->SetMarkerColor(kBlue);
   gamma->SetLineColor(kBlue);
   gamma->SetMarkerStyle(kFullCircle);
   mg->Add(gamma);
   mg->Draw("ALP");
   mg->SetTitle("Title");
   mg->GetXaxis()->SetTitle("x (m)");
   mg->GetYaxis()->SetTitle("y (m)");
   mg->GetYaxis()->SetTitleOffset(offy);
  
   c36->Modified();
   
   c36->Update();
 TF1 *myfit = new TF1("myfit", FunFit);
   myfit->SetParNames("a", "b", "c");
   myfit->SetParameters(1, 1, 1);
 
   const char *fit_options = ""; // e.g. "" or "L" or "W" or "WW"
   myfit->SetParameters(1, 1, 1);
  myfit->SetLineColor(kOrange);
   //fitdistrlatele->SetLineStyle(8);
   mg->Fit(myfit, fit_options);
  
   c->Update();
   c36->Modified();
   c36->Update();
    TLegend* leg10 = new TLegend(0.7, 0.83, .6, .89);
    leg10->SetNColumns(1);
    leg10->AddEntry(gamma, "Dati", "lp");
    leg10->Draw("same");
   c36->Modified();
   gROOT->SetBatch();
   c36->Print(dataout);delete c36;
   gROOT->SetBatch();
	exit();
  
   }