#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:

Comment (by Peter Diener):

I suggest adding the following to the end of section 3.4:

In both cases, the derivatives are not calculated in ghost zones of inter-processor or symmetry boundaries, i.e. the returned derivatives are undefined in ghost zones and will require synchronization of either the derivatives or the evolved fields depending on the scheme used.

It would be wrong to switch to use one sided derivatives in ghost zones as, for most operators, the region, where one sided derivatives would be calculated, is larger than the ghost region. Hence some cells where centered finite differences could be calculated would contain one sided derivatives and the result would depend on the number of processors used.

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