program fixper
      implicit none
      integer*4 np0,nc0,i,j,ii,k,nint,nx,ny,nc,il,ixa,ixi,iya,iyi,
     1xmin,xmax,ymin,ymax,xstep,ystep,x,y,xper,yper,xk,yk,in
      parameter (np0=10000,nc0=10)
      real*4 bu(nc0),rec(np0,nc0),rt(nc0),emin
      logical lex
      write(6,*)'Adds extra periodic points in the LIST.TXT'
      inquire(file='FIXPER.PAR',exist=lex)
      if(lex)then
       write(6,*)'FIXPER.PAR found'
       open(55,file='FIXPER.PAR')
       read(55,*)xmin,xmax,ymin,ymax,xstep,ystep
       read(55,*)xper,yper
       read(55,*)nc
       close(55)
      else
       write(6,*)'Input desired limits, coordinates must be integers'
       write(6,*)
       write(6,*)'xmin xmax ymin ymax xstep ystep:'
       read(5,*)xmin,xmax,ymin,ymax,xstep,ystep
       write(6,*)'Input periods:'
       write(6,*)'xper yper:'
       read(5,*)xper,yper
       write(6,*)'Number of columns in LIST.TXT:'
       read(5,*)nc
      endif
      nx=(xmax-xmin)/xstep+1
      ny=(ymax-ymin)/ystep+1
      write(6,6001)nx,ny,nx*ny
6001  format(i4,' x ',i4,' = ',i5)
      if(nx*ny.gt.np0)call report('too many points')
      if(nc.gt.nc0)call report('too many columns')

      open(8,file='LIST.TXT')
      il=0
1     read(8,*,end=99,err=99)(bu(i),i=1,nc)
      il=il+1
      if(il.gt.np0)call report('too many read points')
      x=nint(bu(1))
      y=nint(bu(2))
c     put omega in (-180,180> and energies in kcal/mol:
      bu(3)=bu(3)+real(360*nint((-180.0+bu(3))/(-360.0)))
      do 2 i=1,nc
2     rec(il,i)=bu(i)
      if(il.eq.1)then
       ixi=x
       ixa=x
       iyi=y
       iya=y
       emin=bu(nc)
      else
       if(x.lt.ixi)ixi=x
       if(y.lt.iyi)iyi=y
       if(x.gt.ixa)ixa=x
       if(y.gt.iya)iya=y
       if(emin.gt.bu(nc))emin=bu(nc)
      endif
      goto 1
99    close(8)

      write(6,*)il,' lines'
      write(6,*)' xmin:',ixi
      write(6,*)' xmax:',ixa
      write(6,*)' ymin:',iyi
      write(6,*)' ymax:',iya
      write(6,*)' emin:',emin

      open(8,file='LISTF.TXT')
      do 3 i=1,nx
      x=xmin+(i-1)*xstep
      do 3 j=1,ny
      y=ymin+(j-1)*ystep
      in=0
      do 7 ii=3,nc
7     rt(ii)=0.0
      do 4 k=1,il
      xk=nint(rec(k,1))
      yk=nint(rec(k,2))
      if((xk     .eq.x.and.yk     .eq.y).or.
     1   (xk-xper.eq.x.and.yk     .eq.y).or.
     1   (xk+xper.eq.x.and.yk     .eq.y).or.
     1   (xk     .eq.x.and.yk+yper.eq.y).or.
     1   (xk     .eq.x.and.yk-yper.eq.y).or.
     1   (xk+xper.eq.x.and.yk+yper.eq.y).or.
     1   (xk+xper.eq.x.and.yk-yper.eq.y).or.
     1   (xk-xper.eq.x.and.yk+yper.eq.y).or.
     1   (xk-xper.eq.x.and.yk-yper.eq.y))then
       in=in+1
       do 5 ii=3,nc
5      rt(ii)=rt(ii)+rec(k,ii)
      endif
4     continue
      if(in.eq.0)then
       write(6,*)x,y,'point cannot be found'
      else
       do 6 ii=3,nc
6      rt(ii)=rt(ii)/real(in)
c      write(8,6002)x,y,(rt(ii),ii=3,nc)
c      relative energies in kcal/mol:
       write(8,6002)x,y,(rt(ii),ii=3,nc-1),(rt(nc)-emin)*627.5
6002   format(2i5,8f15.6)
      endif
3     continue
      close(8)
      stop
      end

      subroutine report(s)
      character*(*) s
      write(6,*)s
      stop
      end