RW-Ntuple duplicated with selection

In this example, a RWN ntuple is duplicated and filled with a subset of the original one. The subset is: ``the people with at least 3 childrens''.

A sub-Ntuple with children >= 3
      opt stat
      hi/file 1 rwn_aptuple.hbook
1     HI/FILE 2 RWN_APTUPLE_DUP.HBOOK ! N                                                      
2     NT/DUPL //LUN1/10 100                                                                    
      *
      application comis quit
            real function dup
4           INCLUDE ?                                                                          
5           IF (CHILDREN.GE.3) CALL HFN(100,CATEGORY)                                          
            dup=1.
            end
      Quit
      *
3     NT/LOOP //LUN1/10 dup                                                                    
      hrout 100
      nt/plot //lun1/10.children
      set hcol 1105
      nt/plot //lun2/100.children option=s

Create a new HBOOK file to store the ``subset-Ntuple''
Duplicate the structure of the original Ntuple. The subset will be stored in this duplicated ntuple.
Loop over the original Ntuple with the function ``dup''.
The special COMIS statement avoid to do UWFUNC .
When an event is selected, HFN is called to fill the ``subset-Ntuple''

			PAW Tutorial	Last update: 1999/04/01 14.59	Olivier.Couet@Cern.Ch