cdeck homer7
      subroutine homer7 (coor,i,j)
c   subroutine to exchange coordinates at locations i and j
      real coor(3,1)
      if (i.eq.j) return
         do 10 k=1,3
            temp=coor(k,i)
            coor(k,i)=coor(k,j)
            coor(k,j)=temp
   10    continue
      return
      end