anchor.diff:        real*8  a(3,3),b(3,3),volume
         integer i,j
   
  -*      **** external functions ****
  -       real*8   lattice_unita
  -       external lattice_unita
   
   *     ***** Determine the unit lattice vectors and distances ******
         do j=1,3
         do i=1,3
  -        a(i,j) = lattice_unita(i,j)
  +        a(i,j) = unita(i,j)
         end do
         end do
   
  
positive.code: 
     23   IF ((f2(1)-f1(1)) .GT. (0.5d0)) THEN
  *          WRITE (*,*) 'a1>', I, R2A1, DA(1)/2.0d0
             r2(1,i) = r2(1,i) - lattice_unita(1,1)
             r2(2,i) = r2(2,i) - lattice_unita(2,1)
             r2(3,i) = r2(3,i) - lattice_unita(3,1)
  
              f2(1) =  b(1,1) * r2(1,i)
       >            +  b(2,1) * r2(2,i)
  
negative.code: 
     27   IF ((f2(3)-f1(3)) .GT. (0.5d0)) THEN
  *         WRITE (*,*) 'a3>', i, R2A3, DA(3)/2.0d0
            r2(1,i) = r2(1,i) - unita(1,3)
            r2(2,i) = r2(2,i) - unita(2,3)
            r2(3,i) = r2(3,i) - unita(3,3)
  
            f2(3) =  b(1,3) * r2(1,i)
       >          +  b(2,3) * r2(2,i)
  