<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Mar 11, 2016, at 8:53 PM, Matthew Knepley <<a href="mailto:knepley@gmail.com" class="">knepley@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" style="font-family: Calibri; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class="gmail_extra"><div class="gmail_quote">On Fri, Mar 11, 2016 at 12:26 PM, Dave May<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:dave.mayhem23@gmail.com" target="_blank" class="">dave.mayhem23@gmail.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><span class="">On 11 March 2016 at 18:11, anton<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:popov@uni-mainz.de" target="_blank" class="">popov@uni-mainz.de</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">Hi team,<br class=""><br class="">I'm implementing staggered grid in a PETSc-canonical way, trying to build a custom DM object, attach it to SNES, that should later transfered it further to KSP and PC.<br class=""><br class="">Yet, the Galerking coarsening for staggered grid is non-symmetric. The question is how possible is it that DMShellSetCreateRestriction can be implemented and included in 3.7 release?<br class=""></blockquote><div class=""><br class=""></div></span><div class="">It's a little more work than just adding a new method within the DM and a new APIs for DMCreateRestriction() and DMShellSetCreateRestriction().<br class=""></div><div class="">PCMG needs to be modified to call DMCreateRestriction().<span class="Apple-converted-space"> </span><br class=""></div></div></div></div></blockquote><div class=""><br class=""></div><div class="">Dave is correct. Currently, PCMG only calls DMCreateInterpolation(). We would need to add a DMCreateRestriction() call.</div></div></div></div></div></blockquote>The PCMG object already uses a restriction operator that is different from the interpolation parameter if it is specified with<span style="color: rgb(178, 34, 34); background-color: rgb(255, 255, 255);" class=""> </span><a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCMGSetRestriction.html#PCMGSetRestriction" class="">PCMGSetRestriction</a>. </div><div>For consistency, one would expect a similar DMCreateRestriction object, not? I realize that this is not relevant for FEM codes, but for staggered FD it makes quite some difference. </div><div><br class=""></div><div>Other suggestions on how to best integrate staggered finite differences within the current PETSc framework are ofcourse also highly welcome. </div><div>Our current thinking was to pack it into a DMSHELL (which has the problem of not having a restriction interface). </div><div><br class=""></div><div>thanks,</div><div>Boris</div><div><br class=""></div><div><br class=""></div><div><br class=""></div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" style="font-family: Calibri; font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""> Thanks,</div><div class=""><br class=""></div><div class=""> Matt</div><div class=""> </div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""></div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;">Please, please.<br class=""><br class="">Thanks,<br class="">Anton<br class=""><br class=""></blockquote></div></div></div></blockquote></div><div class=""><br class=""></div>--<span class="Apple-converted-space"> </span><br class=""><div class="gmail_signature">What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br class="">-- Norbert Wiener</div></div></div></div></blockquote></div><br class=""></body></html>