[Carpet] Regridding and scheduling in new version of Carpet

[Ian Hinder]

Erik Schnetter wrote:

> The easiest solution would be to set the grid hierarchy in different
> ways in PREREGRIDINITIAL and in PREREGRID.  I find that setting up the
> initial grid hierarchy and modifying the grid hierarchy later on are
> sufficiently different that using the same method doesn't quite work.

After reading more carefully how CarpetRegrid2 works, I came to the same
conclusion.  For the record, I now run my regridding thorn in
PREREGRIDINITIAL and in PREREGRID, but in the first bin I take the
locations of the centres from parameters, and in the second bin I take
it from spherical surfaces.  This now works.

For people wanting to continue using CarpetRegrid rather than
CarpetRegrid2, I want to point out that the behaviour between
carpet-stable-3 and current Carpet development has not changed.  You
still have to manually add the buffer zones to the coordinates string
(or whatever method you use).  So the code that I have to do rotating
symmetries works fine as it did before; all I have to do now is know how
many buffer zones to add, as Carpet doesn't have the parameter any more.

>> The documentation in Carpet/doc/scheduling.tex says that the bins are
>> run in the order
>>
>>    [CCTK_BASEGRID]
>>      [CCTK_INITIAL]
>>    [CCTK_PREREGRIDINITIAL]
>>     Regrid
>>    [CCTK_POSTREGRIDINITIAL]
>>
>> and this seems to me to make much more sense, but I understand if it is
>> out of date.
> 
> Yes, this is out of date.  Could you correct it?

Sure.

-- 
Ian Hinder
hinder at gravity.psu.edu
http://www.gravity.psu.edu/~hinder