Resolve "pi0 resolution for ECal barrel"

Closes #19 (closed)

benchmarks/barrel_ecal/scripts/emcal_barrel_pions_analysis.cxx

@@ -95,14 +95,36 @@ void emcal_barrel_pions_analysis(const char* input_fname = "sim_output/sim_emcal
     return result;
   };
 
+  // Energy Resolution = Esampling - Ethrown
+  auto eResol = [](const std::vector<double>& sampled, const std::vector<double>& thrown) {
+    std::vector<double> result;
+    auto it_sam = sampled.cbegin();
+    auto it_thr = thrown.cbegin();
+    for (; it_sam != sampled.end() && it_thr != thrown.end(); ++it_sam, ++it_thr) {
+        result.push_back(*it_sam - *it_thr);
+    }
+    return result;
+  };
+
+  // Relative Energy Resolution = (Esampling - Ethrown)/Ethrown
+  auto eResol_rel = [](const std::vector<double>& sampled, const std::vector<double>& thrown) {
+    std::vector<double> result;
+    auto it_sam = sampled.cbegin();
+    auto it_thr = thrown.cbegin();
+    for (; it_sam != sampled.end() && it_thr != thrown.end(); ++it_sam, ++it_thr) {
+        result.push_back((*it_sam - *it_thr) / *it_sam);
+    }
+    return result;
+  };
+
   // Define variables
   auto d1 = d0.Define("Ethr",  Ethr,  {"mcparticles"})
-	      .Define("nhits", nhits, {"EcalBarrelHits"})
-	      .Define("Esim",  Esim,  {"EcalBarrelHits"})
+	      .Define("nhits",  nhits,      {"EcalBarrelHits"})
+	      .Define("Esim",   Esim,       {"EcalBarrelHits"})
 	      //.Define("fsam",  fsam,  {"Esim","Ethr"})
-        .Define("fsam",  fsam2,  {"Esim","Ethr"})
-        .Define("dE", "Ethr-Esim")
-        .Define("dE_rel", "(Ethr - Esim)/Esim")
+        .Define("fsam",   fsam2,      {"Esim","Ethr"})
+        .Define("dE",     eResol,     {"Esim", "Ethr"})
+        .Define("dE_rel", eResol_rel, {"Esim", "Ethr"})
 	      ;
 
   // Define Histograms