anchor.diff:                if (tet_nodes(i) .eq. nearest_node_index) then
                     calculate_dirac = .true.
                     
  -                  temp = tet_nodes(i)
  +                  swap_temporary = tet_nodes(i)
                     tet_nodes(i) = tet_nodes(4)
  -                  tet_nodes(4) = temp
  +                  tet_nodes(4) = swap_temporary
                     goto 10
                 end if
             end do
  
positive.code:           implicit none
            include 'fem3Dtet.fd'
  
            Real*8  x, y, z, DATA(*), Coef(9, *)
            Integer label, iSYS(*)
  
            Integer i, j
  
negative.code: c === ./dirac.f      
            real*8 dirac_value
            integer nearest_node_index
            logical calculate_dirac
  c === ./lininterp.f
            real*8 linterpvalue
  c ==========      
  