anchor.diff:  
       radial = (p%r .dot. p%v) > 0.
   
  -    if(debug) write(*,'(" [debug] start grid_integrate")')
  +    if(debug) write(*,'(" [debug] start grid_escape_tau")')
   
       ! Find what cell we are in if we don't know
   
  
positive.code: 
      radial = (p%r .dot. p%v) > 0.
  
      if(debug) write(*,'(" [debug] start grid_integrate")')
  
      ! Find what cell we are in if we don't know
  
  
negative.code: 
      radial = (p%r .dot. p%v) > 0.
  
      if(debug) write(*,'(" [debug] start grid_integrate_noenergy")')
  
      ! Set tau achieved to zero
  
  