FeldmanCousins.C

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/// \file
/// \ingroup tutorial_math
/// \notebook -nodraw
/// Example macro of using the TFeldmanCousins class in root.
///
/// get a FeldmanCousins calculation object with the default limits
/// of calculating a 90% CL with the minimum signal value scanned
/// = 0.0 and the maximum signal value scanned of 50.0
///
/// \macro_output
/// \macro_code
///
/// \author Adrian John Bevan <bevan@SLAC.Stanford.EDU>

void FeldmanCousins()
{
   if (!gROOT->GetClass("TFeldmanCousins"))
      R__LOAD_LIBRARY(libPhysics);

   TFeldmanCousins f;

   // calculate either the upper or lower limit for 10 observed
   // events with an estimated background of 3.  The calculation of
   // either upper or lower limit will return that limit and fill
   // data members with both the upper and lower limit for you.
   Double_t Nobserved   = 10.0;
   Double_t Nbackground = 3.0;

   Double_t ul = f.CalculateUpperLimit(Nobserved, Nbackground);
   Double_t ll = f.GetLowerLimit();

   cout << "For " <<  Nobserved << " data observed with and estimated background"<<endl;
   cout << "of " << Nbackground << " candidates, the Feldman-Cousins method of "<<endl;
   cout << "calculating confidence limits gives:"<<endl;
   cout << "\tUpper Limit = " <<  ul << endl;
   cout << "\tLower Limit = " <<  ll << endl;
   cout << "at the 90% CL"<< endl;
}