[ET Trac] [Einstein Toolkit] #1236: ReflectionSYmmetry does not handle vector groups of vectors correctly

[Einstein Toolkit]

#1236: ReflectionSYmmetry does not handle vector groups of vectors correctly
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 Reporter:  rhaas                                                      |       Owner:     
     Type:  defect                                                     |      Status:  new
 Priority:  minor                                                      |   Milestone:     
Component:  Cactus                                                     |     Version:     
 Keywords:  RelfectionSymmetry RotatingSymmetry180 RotatingSymmetry90  |  
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 Currently we use two different way to define vectors in Cactus:
 {{{
 CCTK_REAL vel[3] "some vector variable"
 }}}
 and
 {{{
 CCTK_REAL vel
 {
   velx, vely, velz
 } "some other vector variable"
 }}}
 both of which work with ReflectionSymmetry since it only looks at the
 ordering of variables in a group (ie does vi=CCTK_FirstVarInGroup() then
 assumes vi is the x component vi+1 the y component and vi+2 the z
 component).

 For a group of related vectors we'd like to use
 {{{
 CCTK_REAL nvel[42]
 {
   velx, vely, velz
 } "bunch of vector"
 }}}
 which almost works in the indeed CCTK_VarIndex("velx[0]") + 1 ==
 CCTK_VarIndex("vely[0]"). Unfortunately the symmetry thorns assume that
 vector groups contain precisely three members. A simple fix seems to
 instead assert() that the number of members is divisible by 3 and then
 loop over them in chunks of three.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1236>
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