[Carpet] "proper nesting" in the presence of symmetries

[Jonathan Thornburg]

Hi, Erik,

I am running Carpet on a single processor.
I have a par file (attached) which sets up a grid like this,
using RotatingSymmetry90 with its default settings:

Carpet::domain_from_coordbase = true
driver::ghost_size               = 3
Carpet::buffer_width             = 9

Carpet::prolongation_order_space = 3
Carpet::prolongation_order_time  = 2
Carpet::num_integrator_substeps  = 4

CoordBase::domainsize = "minmax"	# specify continuum domain
CoordBase::xmin =   0.0
CoordBase::xmax = +10.0
CoordBase::ymin =   0.0
CoordBase::ymax = +10.0
CoordBase::zmin = -10.0
CoordBase::zmax = +10.0
CoordBase::dx   =   0.4
CoordBase::dy   =   0.4
CoordBase::dz   =   0.4

ActiveThorns = "CarpetRegrid"
CarpetRegrid::refinement_levels = 3
CarpetRegrid::refined_regions = manual-coordinate-list
CarpetRegrid::smart_outer_boundaries = yes
CarpetRegrid::coordinates = "[
   [ ([ 0.0, 0.0,-5.0] : [ 5.0, 5.0, +5.0] : [0.2, 0.2, 0.2])], 
   [ ([ 0.0, 0.0,-3.0] : [ 3.0, 3.0, +3.0] : [0.1, 0.1, 0.1])] 
                             ]"
CarpetRegrid::keep_same_grid_structure = yes
CarpetLib::save_memory_during_regridding = yes

CartGrid3D::type         = "CoordBase"
CartGrid3D::avoid_origin = false

Carpet complains that the grid isn't properly nested:

INFO (Carpet): Recomposing the grid hierarchy for map 0
Not properly nested: rl=1, required distance=4
Received from level 0: bboxset<CCTK_INT4,3>:size=45168,setsize=4,set={([1536,1536,14336]:[17408,17408,19968]:[512,512,512]),([11776,1536,20480]:[17408,17408,43008]:[512,512,512]),([1536,11776,20480]:[11264,17408,43008]:[512,512,512]),([1536,1536,37376]:[11264,11264,43008]:[512,512,512])}
Taboo region on level 1: bboxset<CCTK_INT4,3>:size=94000,setsize=4,set={([-512,-512,12288]:[19456,19456,22016]:[512,512,512]),([9728,-512,22528]:[19456,19456,45056]:[512,512,512]),([-512,9728,22528]:[9216,19456,45056]:[512,512,512]),([-512,-512,35328]:[9216,9216,45056]:[512,512,512])}
Sent to level 2: bboxset<CCTK_INT4,3>:size=10451,setsize=4,set={([2048,2048,19968]:[11776,11776,23040]:[512,512,512]),([8704,2048,23552]:[11776,11776,37376]:[512,512,512]),([2048,8704,23552]:[8192,11776,37376]:[512,512,512]),([2048,2048,34304]:[8192,8192,37376]:[512,512,512])}
Overlap on level 1: bboxset<CCTK_INT4,3>:size=8375,setsize=4,set={([2048,2048,19968]:[11776,11776,22016]:[512,512,512]),([9728,2048,22528]:[11776,11776,37376]:[512,512,512]),([2048,9728,22528]:[9216,11776,37376]:[512,512,512]),([2048,2048,35328]:[9216,9216,37376]:[512,512,512])}
WARNING level 1 in thorn CarpetLib processor 0 host carbon.aei.mpg.de
  (line 695 of /home/jonathan/cactus/Cactus/configs/test-moving-excision/build/CarpetLib/dh.cc): 
  -> Not properly nested

I am confused as to just where the improper nesting lies:  there
seems to be lots of space between the upper faces of the various
refinement boxes, and the lower faces are symmetry planes in xy,
and have lots of space in z.

Can you tell me just what the rules are which define "proper nesting"?

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