calculates sampling fraction and then uses that to correctly calculate the resolution 2

benchmarks/barrel_ecal/scripts/emcal_barrel_pions_analysis.cxx

@@ -126,7 +126,7 @@ void emcal_barrel_pions_analysis(const char* input_fname = "sim_output/sim_emcal
               .Define("pid",    getpid,     {"mcparticles"})
               ;
   // Set sampling Fraction, ideally this will be taken from a json file 
-  samp_frac = &d1.Mean<double>("fsam");
+  samp_frac = *d1.Mean<double>("fsam");
 
   auto d2 = d1.Define("dE",     eResol,     {"Esim","Ethr"})
               .Define("dE_rel", eResol_rel, {"Esim","Ethr"})