[Trigger] Fix covariance matrix filling for 128bits words (#10562)

Author: mpuccio

EventFiltering/cefpTask.cxx

@@ -359,21 +359,24 @@ struct centralEventFilterTask {
     mFiltered->SetBinContent(1, mFiltered->GetBinContent(1) + nEvents - startCollision);
 
     for (uint64_t iE{0}; iE < outTrigger.size(); ++iE) {
+      const auto& triggerWord{outTrigger[iE]};
       bool triggered{false}, selected{false};
-      for (uint64_t iD{0}; iD < outTrigger[0].size(); ++iD) {
+      for (uint64_t iD{0}; iD < triggerWord.size(); ++iD) {
         for (int iB{0}; iB < 64; ++iB) {
-          if (!(outTrigger[iE][iD] & BIT(iB))) {
+          if (!(triggerWord[iD] & BIT(iB))) {
             continue;
           }
-          for (uint64_t jD{0}; jD < outTrigger[0].size(); ++jD) {
-            for (int iC{iB}; iC < 64; ++iC) {
-              if (outTrigger[iE][iD] & BIT(iC)) {
-                mCovariance->Fill(iD * 64 + iB, jD * 64 + iC);
+          uint64_t xIndex{iD * 64 + iB};
+          for (uint64_t jD{0}; jD < triggerWord.size(); ++jD) {
+            for (int jB{0}; jB < 64; ++jB) {
+              uint64_t yIndex{jD * 64 + jB};
+              if (xIndex <= yIndex && triggerWord[jD] & BIT(jB)) {
+                mCovariance->Fill(iD * 64 + iB, jD * 64 + jB);
               }
             }
           }
         }
-        triggered = triggered || outTrigger[iE][iD];
+        triggered = triggered || triggerWord[iD];
         selected = selected || outDecision[iE][iD];
       }
       if (triggered) {