[ET Trac] [Einstein Toolkit] #2131: Boundary thorn

[Einstein Toolkit]

#2131: Boundary thorn
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 Reporter:  miguel.zilhao.nogueira@…                   |       Owner:                     
     Type:  defect                                     |      Status:  new                
 Priority:  major                                      |   Milestone:                     
Component:  EinsteinToolkit thorn                      |     Version:  development version
 Keywords:  Boundary                                   |  
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 i was trying to do a (unigrid) run with "scalar" boundary conditions on
 some variables but with uneven boundary width, ie width of 2 grid points
 on the x and y axis and 0 on the z axis. in the documentation of the
 Boundary thorn it states that one should create a table passing this
 information in an array called "BOUNDARY_WIDTH":

 "The table handle identifies a table which holds extra arguments for the
 particular boundary condition that is requested. For example, if a
 negative value is passed for the boundary width, then the boundary
 condition will look in this table for a 2d-element integer array, which
 holds the width of each face of the boundary (for a d dimensional grid
 variable). (The first element of the array holds the width of the ‘-x’
 face, the second the ‘+x’ face, the third the ‘-y’ face, etc.)"

 so i've accordingly created the following table
 {{{
   call Util_TableCreateFromString(param_table_handle, "BOUNDARY_WIDTH = {
 2 2 2 2 0 0 }")
 {{{
 and then registered the variables with
 {{{
    ierr = Boundary_SelectGroupForBC(cctkGH, CCTK_ALL_FACES, -one,
 &
         param_table_handle, "ScalarBase::phi", "scalar")
 }}}
 however, i was getting errors like the following:
 {{{
   Boundary/src/Check.c:130: BndSanityCheckWidths: Assertion `dim <
 (int)sizeof(dims)' failed.
 }}}
 inspecting that file, this is only triggered if {{{(boundary_widths[i] >
 100 || boundary_widths[i] < 0)}}} which meant that my BOUNDARY_WIDTH array
 was likely not being parsed correctly. digging a little bit deeper, i've
 found the following in ScalarBoundary.c:138 (and analogous for the other
 files under CactusBase/Boundary/src):
 {{{
      /* Determine boundary width on all faces */
      /* allocate memory for buffer */
      gdim = CCTK_GroupDimI(gi);
      if (gdim > max_gdim) {
        width_alldirs =
            (CCTK_INT *)realloc(width_alldirs, 2 * gdim *
 sizeof(CCTK_INT));
        max_gdim = gdim;
      }

      /* fill it with values, either from table or the boundary_width
         parameter */
      if (widths[i] < 0) {
        err = Util_TableGetIntArray(tables[i], gdim, width_alldirs,
                                    "BOUNDARY_WIDTH");
 }}}
 it seems to me that this last line should be instead
 {{{
        err = Util_TableGetIntArray(tables[i], 2 * gdim, width_alldirs,
                                    "BOUNDARY_WIDTH");
 }}}
 for consistency with the rest of the file and with the documentation,
 right? indeed, with this change the errors disappeared. i've attached a
 simple patch that applies this on this file, but i guess an equivalent
 change would be needed also for the rest of the Boundary files...

 if this patch is correct, could this be ported to the current release? and
 if it's not correct, is there anything i'm missing, in order to register
 the boundary conditions?

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/2131>
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