When calculating a*a-b*b the form (a-b)*(a+b) is usually more numerically stable.

[u/mrichter/AliRoot.git] / EVGEN / AliGenHBTosl.cxx

diff --git a/EVGEN/AliGenHBTosl.cxx b/EVGEN/AliGenHBTosl.cxx
index 1dd0529440c44a01d3731e6cd0682af01844458f..50695409f233ff0d9125151bfce33243ef29497e 100644 (file)
--- a/EVGEN/AliGenHBTosl.cxx
+++ b/EVGEN/AliGenHBTosl.cxx
@@ -1565,7 +1565,7 @@ void  AliGenHBTosl::GetQOutQSideQLong(TParticle* f, TParticle* s,Double_t& out,
   }
 
  Double_t beta = pzsum/esum;
- Double_t gamma = 1.0/TMath::Sqrt(1.0 - beta*beta);
+ Double_t gamma = 1.0/TMath::Sqrt((1.-beta)*(1.+beta));
 
  lon = gamma * ( pzdiff - beta*ediff );