subroutine nplotter_W_1jet(p,wt,wt2,switch)
c--- Variable passed in to this routine:
c
c---      p:  4-momenta of particles in the format p(i,4)
c---          with the particles numbered according to the input file
c---          and components labelled by (px,py,pz,E)
c
c---     wt:  weight of this event
c
c---    wt2:  weight^2 of this event
c
c--- switch:  an integer equal to 0 or 1, depending on the type of event
c---                0  --> lowest order, virtual or real radiation
c---                1  --> counterterm for real radiation
      implicit none
      include 'vegas_common.f'
      include 'constants.f'
      include 'histo.f'
      include 'jetlabel.f'
      include 'outputflags.f'
      double precision p(mxpart,4),wt,wt2
      double precision yrap,pt,yraptwo,pttwo,r
c---  Z->e+e-(31) or b bbar(33): both measured, rapidities and momenta of 3 and 4 can
c---  be calculated, also the invariant mass m34
      double precision y3,y4,y5,y34,pt3,pt4,pt5,pt34,m34,r35
      double precision ylep, yjet, ptlep, ptjet,costheta,
     & p3(4),p4(4),p34(4)
      double precision ptzl(12),ptzu(12)
      data ptzl/0,12.5,17.5,24,30,40,50,70,110,150,190,250/
      data ptzu/12.5,17.5,24,30,40,50,70,110,150,190,250,600/

      integer switch,n,nplotmax,nproc,exptid
      character*4 tag
      logical first
      common/nplotmax/nplotmax
      common/nproc/nproc
      common/exptid/exptid
      data first/.true./
      save first    

************************************************************************
*                                                                      *
*     INITIAL BOOKKEEPING                                              *
*                                                                      *
************************************************************************

      if (first) then
c--- Initialize histograms, without computing any quantities; instead
c--- set them to dummy values
        tag='book'
      y3=1d3
        y4=1d3
        y5=1d3
        y34=1d3
        pt3=0d0
        pt4=0d0
        pt5=1d3
        pt34=0d0
        m34=0d0
        r35=1d3
        jets=1
c---  (Upper) limits for the plots
        ylep=6d0
        yjet=3.2d0
        ptlep=80d0
        ptjet=100d0
        goto 99
      else
c--- Add event in histograms
        tag='plot'
      endif

************************************************************************
*                                                                      *
*     DEFINITIONS OF QUANTITIES TO PLOT                                *
*                                                                      *
************************************************************************

      y3=yrap(3,p)
      y4=yrap(4,p)
      y34=yraptwo(3,4,p)
      pt3=pt(3,p)
      pt4=pt(4,p)
      pt34=pttwo(3,4,p)
      m34=dsqrt((p(3,4)+p(4,4))**2-(p(3,1)+p(4,1))**2
     .         -(p(3,2)+p(4,2))**2-(p(3,3)+p(4,3))**2)

      if(jets .gt. 0) then
         pt5=pt(5,p)
         y5=yrap(5,p)
         r35=R(p,3,5)
      else
         pt5=-1d0
         y5=1d3
         r35=1d3
      endif
      

************************************************************************
*                                                                      *
*     FILL HISTOGRAMS                                                  *
*                                                                      *
************************************************************************

c--- Call histogram routines
   99 continue

c--- Book and fill ntuple if that option is set, remembering to divide
c--- by # of iterations now that is handled at end for regular histograms
      if (creatent .eqv. .true.) then
        call bookfill(tag,p,wt/dfloat(itmx))  
      endif

c--- "n" will count the number of histograms
      n=nextnplot              

c--- Syntax of "bookplot" routine is:
c
c---   call bookplot(n,tag,titlex,var,wt,wt2,xmin,xmax,dx,llplot)
c
c---        n:  internal number of histogram
c---      tag:  "book" to initialize histogram, "plot" to fill
c---   titlex:  title of histogram
c---      var:  value of quantity being plotted
c---       wt:  weight of this event (passed in)
c---      wt2:  weight of this event (passed in)
c---     xmin:  lowest value to bin
c---     xmax:  highest value to bin
c---       dx:  bin width
c---   llplot:  equal to "lin"/"log" for linear/log scale
           
      if(exptid.eq.111.or.exptid.eq.161) then
      call bookplot2(n,tag,'ptz',pt34,wt,wt2,ptzl,ptzu,12,'lin')
      endif 
      n=n+1     
      call bookplot(n,tag,'yll',abs(y34),wt,wt2,0d0,2.40d0,0.2d0,'lin')
      n=n+1
      call bookplot(n, tag,'mll',m34,wt,wt2,61d0,121d0,1d0,'lin')
      n=n+1

************************************************************************
*                                                                      *
*     FINAL BOOKKEEPING                                                *
*                                                                      *
************************************************************************

c--- We have over-counted the number of histograms by 1 at this point
      n=n-1

c--- Ensure the built-in maximum number of histograms is not exceeded    
      call checkmaxhisto(n)

c--- Set the maximum number of plots, on the first call
      if (first) then
        first=.false.
        nplotmax=n
      endif
      
      return 
      end