fix possible (in theory) divide by zero

diff --git a/PWG2/FLOW/AliFlowCommon/AliFlowAnalysisWithLeeYangZeros.cxx b/PWG2/FLOW/AliFlowCommon/AliFlowAnalysisWithLeeYangZeros.cxx
index d6c598225a62e275f780350383695e8cbcbff1ec..3b23f8555fe6dafc7e76cd7e339593353567c95d 100644 (file)
--- a/PWG2/FLOW/AliFlowCommon/AliFlowAnalysisWithLeeYangZeros.cxx
+++ b/PWG2/FLOW/AliFlowCommon/AliFlowAnalysisWithLeeYangZeros.cxx
@@ -326,13 +326,16 @@ Bool_t AliFlowAnalysisWithLeeYangZeros::Make(AliFlowEventSimple* anEvent)
        dR0 = fHist1[theta]->GetR0();
                                   
        //calculate integrated flow
-       if (dR0!=0) { dVtheta = dJ01/dR0; }
+       if (dR0!=0.) { dVtheta = dJ01/dR0; }
        else { cout<<"r0 is not found! Leaving LYZ analysis."<<endl; return kFALSE; }
 
        //for estimating systematic error resulting from d0
        Double_t dBinsize = (AliFlowLYZConstants::fgMax)/(AliFlowLYZConstants::kNbins);
-       Double_t dVplus = dJ01/(dR0+dBinsize);
-       Double_t dVmin = dJ01/(dR0-dBinsize);
+       Double_t dVplus = -1.;
+       Double_t dVmin  = -1.;
+       if (dR0+dBinsize!=0.) {dVplus = dJ01/(dR0+dBinsize);}
+       if (dR0-dBinsize!=0.) {dVmin = dJ01/(dR0-dBinsize);}
+       //convert V to v (normally v = V/M, but here V=v because the Q-vector is scaled by 1/M)
        dv = dVtheta;
        Double_t dvplus = dVplus;
        Double_t dvmin = dVmin;