c*******************************************************
c init_juxta(n,np600)
c
c np600=0 no monitor of pair distance evolution
c np600=1 output the distance vs. time directly
c np600=2 output distribution of distance and juxta time

      subroutine init_juxta(n,np600)
      
      implicit double precision(a-h, o-z)

      parameter(maxpair=100,maxa=500,maxjudge=10,nbucket=100)
      common /juxtapair/ npair,npairs(maxpair,2),nflag(maxpair,maxjudge)
     +,njudge, sjuxta_judge(maxjudge),mp(maxpair)
      common/juxta_distribution/d_min,d_max,d_bucket,
     + npair_bucket(nbucket,maxpair)
  
      if (np600.eq.0) then
       open(unit=330,file='Init_juxtadistance',status='old')
       read(330,*) njudge
        do i=1,njudge
           read(330,*) sjuxta_judge(i)
c           write(*,*) i,sjuxta_judge(i) 
           nflag(1,i)=0
        enddo
       close(330)
      endif

      if (np600.ge.1) then 
       open(unit=330,file='Init_juxtapair',status='old')
        read(330,*) npair
        do i=1,npair
         read(330,*) npairs(i,1),npairs(i,2)
         mp(i)=600+min((npairs(i,2)-npairs(i,1)),(n+npairs(i,1)
     +-npairs(i,2)))
c         write(*,*) 'mp(',i,')=',mp(i)
        enddo
      endif

      if (np600.eq.2) then
       read(330,*) njudge
       do i=1,njudge
          read(330,*) sjuxta_judge(i)
       enddo

c setup pair_standard
c can be changed into nonlinear buckets
c now only using the simplest linear on
c try other better mapping algorithms later
          read(330,*) d_min,d_max
          d_bucket=(d_max-d_min)/nbucket
       
c initialize the distribution box, nflag

        do j=1,npair
          do i=1,nbucket        
           npair_bucket(nbucket,maxpair)=0
          enddo
        enddo
        do i=1,njudge
           do j=1,npair
              nflag(j,i)=0
           enddo
        enddo
          
      endif

      return
      end