subroutine connect
!
!     loads arrays to do ffts on connected domain,
!     instead of using extensions
!
  use itg_data
  implicit none	

  integer :: jmax,kmax,jshift,jshift0
  integer, allocatable, dimension(:,:) :: l
  integer :: t, m, n, count, jj, i, j, k, ncon_tmp
  
  allocate (l(-nd:nd,0:md))
  allocate (conpos(md, nd), mcon(md, nd), icon(md, nd))

  jmax=(nd-1)/2
  kmax=md-1
  jshift0=(xp+.0001)/z0*(nd-1)
!  if (jshift0 == 0) jshift0=nz**2
  if (jshift0 == 0) jshift0=nd**2
  
  if((x0 /= xp) .or. (abs(int((x0+.0001)/pi)*pi-x0) >  0.001) &
       .or. (abs(int((xp+.0001)/pi)*pi-xp) >  0.001)) then
     write(*,*) 'failure in connect.f:'
     write(*,*) ' for iconnect=3, must have x0=xp=pi * integer'
     call aborter(6,' ')
  endif

!      write(*,*) 'jmax=',jmax,' kmax=',kmax,' jshift(k=1)=',jshift0
!
!     Calculate how many domains are connected by the BC
!
  do j=-jmax,jmax
     l(j,0)=1
  enddo
  
  do k=1,kmax
     jshift=jshift0*k 
     if (lin == 1 .and. layout == 'linear') jshift=jshift0
     do j=-jmax,jmax
        l(j,k)=(jmax-j)/jshift+(j+jmax)/jshift+1 
        if (j+jmax >= jshift) l(j,k)=0
!          if ((j < 0).and.(l(j,k) > 1)) l(j,k)=0
     enddo
  enddo

!      write(*,*) 'jshift(k=1): ',jshift0
!      write(*,100) 0,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16
100 format(i5,17(i3))
!      do j=-jmax,jmax
!         write(*,100) j,(l(j,k),k=0,kmax)
!      enddo


  nconz = 1
  ndomz = 1
  ndom=1
  do m=1,jmax*2+1
     ncon_tmp=0 
     do k=0,kmax 
        do j=-jmax,jmax
           if (l(j,k) == m) then  
              ncon_tmp=ncon_tmp+1 
              nconz = max(nconz, m)
              ndomz = max(ndomz, ndom)
           endif
        enddo
     enddo
     if (ncon_tmp > 0) ndom=ndom+1
  enddo

  allocate (nncon(ndomz, md*nd), mmcon(ndomz, md*nd))  
  allocate (ncon(ndomz), scon(ndomz))

  t=0
  ndom=1
  do m=1,jmax*2+1
     ncon(ndom)=0 
     do k=0,kmax 
        do j=-jmax,jmax
           if (l(j,k) == m) then  
              ncon(ndom)=ncon(ndom)+1 
              scon(ndom)=m
              if (m > nconz) write(*,*) 'nconz too small, must be at least ',m
              if (ndom > ndomz) write(*,*) 'ndomz too small, must be at least ',ndom 
           endif
        enddo
     enddo
     t=t+ncon(ndom)*m
!        if (ncon(ndom) /= 0) write(*,101) m,ncon(ndom)
! 101    format ('# of connections with m=',i3,': ',i3)
     if (ncon(ndom) > 0) ndom=ndom+1
  enddo

  ndom=ndom-1
  write(*,*) 'total # of domains: ',ndom
  write(*,102) t,(2*jmax+1)*(kmax+1)
102 format('Total modes accounted for: ',i4,'=(2*jmax+1)*(kmax+1)=',i4)
  
  do n=1,nd
     do m=1,md
        j=nrr(n)
        k=mrr(m,n)
        mcon(m,n)=0
        jshift=jshift0*k 
        if (lin == 1 .and. layout == 'linear') jshift=jshift0
        if (k /= 0) then
           icon(m,n)=(jmax-j)/jshift+(j+jmax)/jshift+1 
           conpos(m,n)=1+(jmax-j)/jshift
        else
           icon(m,n)=1
           conpos(m,n)=1
        endif
     enddo
  enddo

  do i=1,ndom
     count=1 
     do k=0,md-1
        do j=-jmax,jmax
           if (l(j,k) == scon(i)) then 
              do jj=1,l(j,k) 
                 jshift=jshift0*k 
                 if (lin == 1 .and. layout == 'linear') jshift=jshift0
                 n=1+j+(jj-1)*jshift
                 if (n < 1) n=n+nd
                 mcon(k+1,n)=count
              enddo
              count=count+1
           endif
        enddo
     enddo
  enddo
  
  goto 7
  write(*,*) 'conpos(m,n)'
  write(*,100) 0,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16
! 100  format(i5,17(i3))
  do j=-jmax,jmax
     n=1+j
     if (n < 1) n=n+nd
     write(*,100) j,(conpos(m,n),m=1,md)
  enddo
  write(*,*) 'icon(m,n)'
  write(*,100) 0,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16
! 100  format(i5,17(i3))
  do j=-jmax,jmax
     n=1+j
     if (n < 1) n=n+nd
     write(*,100) j,(icon(m,n),m=1,md)
  enddo
  write(*,*) 'mcon(m,n)'
  write(*,100) 0,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16
! 100  format(i5,17(i3))
  do j=-jmax,jmax
     n=1+j
     if (n < 1) n=n+nd
     write(*,100) j,(mcon(m,n),m=1,md)
  enddo
  
  write(*,*) 'ndom=',ndom
  do j=1,ndom
     write(*,*) j,' ncon(j)=',ncon(j),' scon(j)=',scon(j)
  enddo
7 continue
  
  do j=1,ndom
     do i=1,ncon(j)
        do k=1,scon(j)
           do m=1,md
              do n=1,nd
                 if ((i == mcon(m,n)).and.(k == conpos(m,n)).and. &
                      (scon(j) == icon(m,n))) then
                    mmcon(j,k+(i-1)*scon(j))=m
                    nncon(j,k+(i-1)*scon(j))=n
                 endif
              enddo
           enddo
        enddo
     enddo
  enddo
  
!      do j=1,ndom
!        do k=1,ncon(j)*scon(j)
!          write(*,103) j,k,mmcon(j,k),nncon(j,k)
!103 format(i4,i4,' mmcon: ',i4,' nncon: ',i4)
!        enddo
!      enddo   
  
  deallocate (l)
end subroutine connect