[Carpet] direction of mglevel?

[Jonathan Thornburg]

Hi, Erik,

Thanks for clarifying mglevel.  Meanwhile, Thomas and I have some
more questions for you, mostly inspired by trying to fix my incorrect
description of when global mode routines are executed:
* I thought the standard loop order has mglevel as the outer loop,
  and reflevel nested inside this.  But I see that the following 3
  parts of the main time evolution loop invert this loop order,
  i.e. do reflevel as outer loop and mglevel nested inside this:
  * PRESTEP + EVOL
  * Restrict
  * POSTRESTRICT + POSTSTEP + CHECKPOINT + ANALYSIS + OutputGH
  Why is the loop order "inside-out" for these?
* In EvolutionI(), are Thomas and I correct in our belief that
    do_global_mode  ==  (rl == 0) ?  If so, why did you write it
   in the more complicated way you did, using the  have_done_global_mode
  flag?
* In EvolutionII() you write the  do_global_mode  computation  in
  terms of  finest_active_reflevel .  We're confused about why
  you do this (when everywhere else it's either  rl == 0   or
  rl == maximum possible rl).  Can you clarify?

thanks, ciao,

-- 
-- Jonathan Thornburg <jthorn at aei.mpg.de>      
   Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut),
   Golm, Germany, "Old Europe"     http://www.aei.mpg.de/~jthorn/home.html      
   "Washing one's hands of the conflict between the powerful and the
    powerless means to side with the powerful, not to be neutral."
                                      -- quote by Freire / poster by Oxfam