#include <TF1.h>
#include <TH1D.h>
#include <TRandom.h>
#include <TCanvas.h>

double test_func( double*, double* );

void mytest()
{
  TCanvas *c1 = new TCanvas("c1", "", 750, 750);
  
  TF1 *f_test_func = new TF1("f_test_func", test_func, -3, 3, 3);
  f_test_func->SetParameters(1200, 0, 1);
  
  TH1D *hh = new TH1D("hh", "", 200, -3, 3);
  
  hh->FillRandom("gaus", 100000);
  hh->Draw();
  f_test_func->Draw("Same");
  c1->Print("testCanv.C");
  
}

double test_func(double *x, double *par)
{
  return par[0]*exp( -(x[0] - par[1])*(x[0] - par[1])/(2*par[2]*par[2]) );
}