Index: trunk/MagicSoft/Mars/mmontecarlo/MMcCollectionAreaCalc.cc
===================================================================
--- trunk/MagicSoft/Mars/mmontecarlo/MMcCollectionAreaCalc.cc	(revision 2237)
+++ trunk/MagicSoft/Mars/mmontecarlo/MMcCollectionAreaCalc.cc	(revision 2250)
@@ -63,4 +63,10 @@
     AddToBranchList("MMcEvt.fEnergy");
     AddToBranchList("MMcEvt.fImpact");
+
+    fCorsikaVersion           =  0;
+    fAllEvtsTriggered         =  kFALSE;
+    fTotalNumSimulatedShowers =  0;
+    fTheta                    = -1.;
+
 } 
 
@@ -76,16 +82,4 @@
     }
 
-    fCollArea = (MHMcCollectionArea*)pList->FindCreateObj("MHMcCollectionArea");
-    if (!fCollArea)
-        return kFALSE;
-
-    fTheta                    =  -1;
-    fEmin                     =  -1;
-    fEmax                     =  -1;
-    fSlope                    =   0;
-    fTotalNumSimulatedShowers =   0;
-    fCorsikaVersion           =   0;
-    fAllEvtsTriggered         = kFALSE;
-
     return kTRUE;
 }
@@ -108,6 +102,6 @@
 
     fTotalNumSimulatedShowers += runheader->GetNumSimulatedShowers();
-
     *fLog << inf << "Total Number of Simulated showers: " << fTotalNumSimulatedShowers << endl;
+
 
     if (fTheta>=0 && fTheta!=runheader->GetTelesTheta())
@@ -116,28 +110,57 @@
         *fLog << fTheta << ", " << runheader->GetTelesTheta() << ")..." << endl;
     }
-
     fTheta = runheader->GetTelesTheta();
+
 
     if (fCorsikaVersion!=0 && fCorsikaVersion!=runheader->GetCorsikaVersion())
         *fLog << warn << dbginf << "Warning - Read files have different Corsika versions..." << endl;
-
     fCorsikaVersion = runheader->GetCorsikaVersion();
 
-    if ( fEmin > 0 &&
-	 (fEmin  != corrunheader->GetELowLim() ||
-	  fEmax  != corrunheader->GetEUppLim() ||
-	  fSlope != corrunheader->GetSlopeSpec()) )
-      *fLog << warn << dbginf << "Warning - Read files have different energy distribution..." << endl;
-
-    fEmin  = corrunheader->GetELowLim();
-    fEmax  = corrunheader->GetEUppLim();
-    fSlope = corrunheader->GetSlopeSpec();
 
     fAllEvtsTriggered |= runheader->GetAllEvtsTriggered();
-
     *fLog << inf << "Only triggered events avail: " << (fAllEvtsTriggered?"yes":"no") << endl;
 
+
+    fCollArea = (MHMcCollectionArea*)plist->FindCreateObj("MHMcCollectionArea");
+    if (!fCollArea)
+        return kFALSE;
+
     if (fAllEvtsTriggered)
+      {
+	//
+	// Calculate approximately the original number of events in each 
+	// energy bin:
+	//
+
+	const Float_t emin = corrunheader->GetELowLim();
+	const Float_t emax = corrunheader->GetEUppLim();
+	const Float_t expo = 1 + corrunheader->GetSlopeSpec();
+	const Float_t k = runheader->GetNumSimulatedShowers() / 
+	  (pow(emax,expo) - pow(emin,expo)) ;
+
+	const Int_t nbinx = fCollArea->GetHistAll()->GetNbinsX();
+
+	for (Int_t i = 1; i <= nbinx; i++)
+	  {
+	    const Float_t e1 = fCollArea->GetHistAll()->GetXaxis()->GetBinLowEdge(i);
+	    const Float_t e2 = fCollArea->GetHistAll()->GetXaxis()->GetBinLowEdge(i+1);
+
+	    if (e1 < emin || e2 > emax)
+	      continue;
+
+	    const Float_t events = k * (pow(e2, expo) - pow(e1, expo));
+	    //
+	    // We fill the ith energy bin, with the total number of events
+	    // Second argument of Fill would be impact parameter of each
+	    // event, but we don't really need it for the collection area,
+	    // so we just put a dummy value (1.)
+	    //
+
+	    const Float_t energy = (e1+e2)/2.;
+	    fCollArea->GetHistAll()->Fill(energy, 1., events);
+	  }
+
         return kTRUE;
+      }
 
     fMcTrig = (MMcTrig*)plist->FindObject(fObjName);
@@ -190,8 +213,8 @@
     {
         *fLog << inf << "Total number of showers: " << fTotalNumSimulatedShowers << endl;
-        fCollArea->CalcEfficiency(fTotalNumSimulatedShowers, fEmin, fEmax, fSlope);
-    }
-
-    return kTRUE;
-}
-
+        fCollArea->CalcEfficiency2();
+    }
+
+    return kTRUE;
+}
+
Index: trunk/MagicSoft/Mars/mmontecarlo/MMcCollectionAreaCalc.h
===================================================================
--- trunk/MagicSoft/Mars/mmontecarlo/MMcCollectionAreaCalc.h	(revision 2237)
+++ trunk/MagicSoft/Mars/mmontecarlo/MMcCollectionAreaCalc.h	(revision 2250)
@@ -5,4 +5,6 @@
 #include "MTask.h"
 #endif
+
+#include <TH2.h>
 
 class MParList;
@@ -23,10 +25,6 @@
     UInt_t fTotalNumSimulatedShowers;
     UInt_t fCorsikaVersion;
+    Bool_t fAllEvtsTriggered;
     Float_t fTheta;
-    Float_t fEmin;
-    Float_t fEmax;
-    Float_t fSlope;
-
-    Bool_t fAllEvtsTriggered;
 
     Bool_t ReInit(MParList *plist);