class HRichUtilFunc: public TObject

 input kine object with momentum vector
 output theta and phi of trajectory

input 2 kine objects
output opening angle of trajectories

input two vectors, output opening angle

 works only correctly for 0 to 90 degrees polar angle

 Returns angle between two directions in DEGREES (input angles in degrees)

input theta and phi of two trajectories
returns opening angle
     Float_t eps=1.e-4;

 this function returns 1 in case that
 the kine obj is a lepton that passed the mirror else 0

 returns 1 if track nb corresponds to a lepton from pi0 Dalitz decay
 else returns zero

 the cuts that need to be applied here depend on the used generator
 of the pi0 Dalitz leptons.
 in case Pluto++ was used to directly decay pi0 in 2 leps and a gamma
 the parent info concerning the pi0 is lost. USE 0 as par part id instead !
 in case that UrQMD has generated the pions, GEANT has decayed them
 and the parent particle id of the leps can be used to check the origin
 returns 1 if track nb corresponds to a lepton from pi0 Dalitz decay
 else returns zero

 returns 1 if track nb corresponds to a lepton from gamma conv
 else returns zero

 returns 1 if kine obj corresponds to a lepton from gamma conv
 gammas came from a pi0
 else returns zero

 input first gamma

 kine is a lepton from a pi0-Dalitz decay
 now find gamma which was 3rd particle in decay

 use this function to save histos every n events
 assumes that you have opened a file and that your
 histograms are stored in a TObjArray

 this should be done using the HSpecGeomPar
 this should be done when alignment for real data
 is used !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 Find HCategory if gHades->getCurrentEvent() is accessible