anchor.diff:      integer :: node1, node2, node3, node4, node5
       REAL(SP), dimension(ndim) :: distance
       REAL(SP), dimension(2**ndim) :: weights, values
  +    REAL(SP), dimension(5) :: denominator
       integer :: i, j, k, l, m
       integer :: npoint
   
  
positive.code:       return
      end if
  
      npoint = 0
      do i = node1, node1 + 1
        do j = node2, node2 + 1
  
negative.code:     integer :: node1, node2
      REAL(SP), dimension(ndim) :: distance
      REAL(SP), dimension(2**ndim) :: weights, values
      REAL(SP), dimension(2) :: denominator
      integer :: i, j
      integer :: npoint
  
  