[Rivet-svn] r3842 - branches/2012-06-aidarivet/src/Analyses

[blackhole at projects.hepforge.org]

Author: richardn
Date: Wed Jul 18 14:40:46 2012
New Revision: 3842

Log:
improved handling of numerical percision problems

Modified:
   branches/2012-06-aidarivet/src/Analyses/MC_VH2BB.cc

Modified: branches/2012-06-aidarivet/src/Analyses/MC_VH2BB.cc
==============================================================================
--- branches/2012-06-aidarivet/src/Analyses/MC_VH2BB.cc	Tue Jul 17 19:20:46 2012	(r3841)
+++ branches/2012-06-aidarivet/src/Analyses/MC_VH2BB.cc	Wed Jul 18 14:40:46 2012	(r3842)
@@ -53,7 +53,16 @@
       double angle1 = b1BOOSTED.angle(virtualVBMomentumBOOSTED);
       double angle2 = b2BOOSTED.angle(virtualVBMomentumBOOSTED);
 
-      double anglebb = b1BOOSTED.angle(b2BOOSTED);
+      double cosbb = b1BOOSTED.vector3().unit().dot(b2BOOSTED.vector3().unit());
+      double test = 1.+cosbb;
+      double anglebb;
+      if(test<0.&&test>-1e-10) {
+	cosbb=-1.;
+	anglebb = M_PI;
+      }
+      else {	
+        anglebb = acos(cosbb);
+      }
 
       vector<double> toReturn;
       toReturn.push_back(angle1 < angle2 ? angle1 : angle2);