<html>#2633: SummationByPart's Diff_gv aliased function does ont document which part of the grid the computed derivative is valid
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<tr><td style='text-align:right'> Reporter:</td><td>Roland Haas</td></tr>
<tr><td style='text-align:right'> Status:</td><td>new</td></tr>
<tr><td style='text-align:right'>Milestone:</td><td></td></tr>
<tr><td style='text-align:right'> Version:</td><td></td></tr>
<tr><td style='text-align:right'> Type:</td><td>bug</td></tr>
<tr><td style='text-align:right'> Priority:</td><td>minor</td></tr>
<tr><td style='text-align:right'>Component:</td><td></td></tr>
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<p>Comment (by Peter Diener):</p>
<p>I suggest adding the following to the end of section 3.4:</p>
<p>In both cases, the derivatives are not calculated in ghost zones of<br>
inter-processor or symmetry boundaries, i.e. the returned derivatives are<br>
undefined in ghost zones and will require synchronization of either the<br>
derivatives or the evolved fields depending on the scheme used.</p>
<p>It would be wrong to switch to use one sided derivatives in ghost zones as,<br>
for most operators, the region, where one sided derivatives would be<br>
calculated, is larger than the ghost region. Hence some cells where centered<br>
finite differences could be calculated would contain one sided derivatives and<br>
the result would depend on the number of processors used.</p>
<p>--<br/>
Ticket URL: <a href='https://bitbucket.org/einsteintoolkit/tickets/issues/2633/summationbyparts-diff_gv-aliased-function'>https://bitbucket.org/einsteintoolkit/tickets/issues/2633/summationbyparts-diff_gv-aliased-function</a></p>
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