anchor.diff:    ps_t = 0.0_WP
     tot_t = 0.0_WP
   
  +  call mass_change
  +
     return
   end subroutine init
   
  
positive.code:   close(unit)
    deallocate(data)
  
    call mass_change
  
    ! Print out initial particle positions
    frame = 0
    call particle_write
  
negative.code:   real(WP) :: total_time
    real(WP) :: twrite
  
  
    init_start = omp_get_wtime()
    time = 0.0_WP
    dt = 0.0_WP
  