#2633: SummationByPart's Diff_gv aliased function does ont document which part of the grid the computed derivative is valid

Reporter: Roland Haas Status: new Milestone: Version: Type: bug Priority: minor Component:

Looking at the code in SummationByParts

```fortran case (0) direction if ( bb(1) == 0 ) then il = 1 + gsize else ol = offset(1) !$omp parallel workshare dvar(1+ol,:,:) = ( q(1,1) * var(1+ol,:,:) + q(2,1) * var(2+ol,:,:) ) * idel dvar(2+ol,:,:) = ( q(1,2) * var(1+ol,:,:) + q(3,2) * var(3+ol,:,:) ) * idel !$omp end parallel workshare il = 3 + ol end if ```

seems to indicate that for non-boundary ends of a grid component (`bb == 0`) derivatives are computed only in the interior (from `il = 1+gsize`) while for boundary ends some (larger) area is valid.

This does not seem to be documented though, at least I could not find it in either documentation.tex nor interface.ccl.

-- Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2633/summationbyparts-d...