anchor.diff:          call elem_rhoz% append(rhoz% data, i, i*tau)
           rhoz% data = 0
           call compute_vxz
  -        call v_xz_el%append(v_xz, i, i*tau)
  +        if (modulo(i, 10)==0) then
  +           call div_vxz(10)
  +           call v_xz_el%append(v_xz, i, i*tau)
  +           v_xz_count = 0
  +           v_xz = 0
  +        end if
           call varia%tac()
   
           call sphere_io%position%append(colloids%pos)
  
positive.code: 
    i = 0
    wall_v = 0
  
    write(*,*) 'Running for', N_loop, 'loops'
    !start RMPCDMD
  
negative.code:   end subroutine rescale_at_walls
  
    subroutine compute_vxz
      integer :: i, s, ix, iy, iz
  
      do i = 1, solvent%Nmax
         s = solvent%species(i)
         if (s <= 0) cycle
  