anchor.diff:    subroutine reset_t()
       implicit none
       tmin = +huge(tmin)
  +    emin = 0.
       imin = no_wall
  +    iext = no_wall
     end subroutine reset_t
   
     subroutine insert_t(t, iw, i, e)
  
positive.code:     type(photon),intent(in) :: p
      type(grid_cell) :: icell_actual
      real(dp) :: frac
  
      icell_actual = find_cell(p)
  
  
negative.code:     allocate(geo%ew2(geo%n2 + 1))
      allocate(geo%ew3(geo%n3 + 1))
  
      geo%ew1 = 3 * spacing(geo%w1)
      geo%ew2 = 3 * spacing(geo%w2)
      geo%ew3 = 3 * spacing(geo%w3)
  
    end subroutine setup_grid_geometry
  
  