[ET Trac] [Einstein Toolkit] #1222: Reduction weight for periodic domains.

[Einstein Toolkit]

#1222: Reduction weight for periodic domains.
-------------------------+--------------------------------------------------
  Reporter:  bentivegna  |       Owner:  eschnett           
      Type:  defect      |      Status:  new                
  Priority:  minor       |   Milestone:                     
 Component:  Carpet      |     Version:  development version
Resolution:              |    Keywords:                     
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Comment (by bentivegna):

 If I understand your argument correctly, I do not agree. Let's say we have
 a periodic domain where we identify x=+1 with x=-1; we cover this with two
 grids, one with spacing dx=0.2 and one with dx/2, and with a lower
 shiftout of 1 and an upper shiftout of 0. With three boundary points, this
 will look like this:

 {{{
            -1                                      +1
             |                                       |
             |                                       |
             |                                       |
 B   B   B   I   I   I   I   I   I   I   I   I   I   B   B   B
       b b b i i i i i i i i i i i i i i i i i i i i b b b
 }}}

 The coordinate of the last internal point will indeed be different on the
 two levels (0.8 on the coarse and 0.9 on the fine), but things like the
 volume of the two levels (assigning weight of 1 to the interior points and
 0 otherwise) is the same:

 C: #I*dx=10*0.2=2
 F: #i*dx/2=20*0.1=2

 Notice that the volume of the two levels is the same with the current
 weight assignment too  -- the patched code produces identical results as
 the current one, when the boundaries have been correctly set. It only
 makes a difference when the boundaries are junk, in which case it prevents
 this junk from polluting the reduction operations.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1222#comment:4>
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