From: ivana <ivana@f7af4fe6-9843-0410-8265-dc069ae4e863>
Date: Fri, 25 Jan 2008 13:56:34 +0000 (+0000)
Subject: Bug fix for sigma computation (at channel level). Still need some
X-Git-Url: http://git.uio.no/git/?a=commitdiff_plain;h=b056545117afec39125a0084d2c0d833bf270690;p=u%2Fmrichter%2FAliRoot.git

Bug fix for sigma computation (at channel level). Still need some
check/work for other levels probably... (to be confirmed)
(Laurent)
---

diff --git a/MUON/AliMUONTrackerData.cxx b/MUON/AliMUONTrackerData.cxx
index 5f23595a0aa..beff1673fc8 100644
--- a/MUON/AliMUONTrackerData.cxx
+++ b/MUON/AliMUONTrackerData.cxx
@@ -779,10 +779,11 @@ AliMUONTrackerData::Value(const AliMUONVCalibParam& param, Int_t i, Int_t dim) c
   }
   else
   {
-    Double_t sumw = param.ValueAsDouble(i,dim-1);
-    Double_t mean = sumw/n;
+    Double_t N = occ;
     
-    return  TMath::Sqrt(TMath::Abs(value/occ - mean*mean));
+    Double_t mean = param.ValueAsDouble(i,dim-1)/N;
+    
+    return  TMath::Sqrt(TMath::Abs((value-N*mean*mean)/(N-1.0)));
   }
   
   AliError("Why am I here ?");