<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Thanks, Matt. <div class=""><br class=""></div><div class="">I also read page 72 in the manual about creating and assembling matrices. </div><div class=""><br class=""></div><div class="">Just so that I understand correctly, MatGetLocalSubMatrix is a generic call to create submatrices in the split-local or split-global space? So, it is primarily a matter of the isrow and iscol? </div><div class=""><br class=""></div><div class="">The manual says that this provides a “view” matrix, so any updates to this submatrix should show up in the global? </div><div class=""><br class=""></div><div class="">How is MatCreateSubMatrixVirtual different? Is this different from a “view” matrix? </div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Mar 29, 2018, at 3:10 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" class=""><div class="gmail_extra"><div class="gmail_quote">On Thu, Mar 29, 2018 at 3:28 PM, Manav Bhatia <span dir="ltr" class=""><<a href="mailto:bhatiamanav@gmail.com" target="_blank" class="">bhatiamanav@gmail.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br class="">
<br class="">
I have quick questions about MatCreateSubMatrix:<br class="">
<br class="">
— Once the sub matrix is created, do I need to keep the IS (isrow and iscol) in memory till this matrix is active, or can I destroy it immediately after the creation of the matrix and continue to use the matrix?<br class=""></blockquote><div class=""><br class=""></div><div class="">You can destroy it.</div><div class=""> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
— Is the assembly begin/end supposed to be called on the submatrix or the original full matrix? Is it a problem is I call this on both?<br class=""></blockquote><div class=""><br class=""></div><div class="">The SubMatrix is not a view. Its a fully independent matrix.</div><div class=""> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
— If I modify values in the sub matrix, would these be reflected in the original matrix after assembly begin/end, or do I need to do something else for that to happen?<br class=""></blockquote><div class=""><br class=""></div><div class="">No. Do you want something like this</div><div class=""><br class=""></div><div class=""> <a href="http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatGetLocalSubMatrix.html" class="">http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatGetLocalSubMatrix.html</a></div><div class=""><br class=""></div><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:1px solid rgb(204,204,204);padding-left:1ex">
Thanks,<br class="">
Manav<br class="">
<br class="">
<br class="">
</blockquote></div><br class=""><br clear="all" class=""><div class=""><br class=""></div>-- <br class=""><div class="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class="">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 class=""><br class=""></div><div class=""><a href="http://www.caam.rice.edu/~mk51/" target="_blank" class="">https://www.cse.buffalo.edu/~knepley/</a><br class=""></div></div></div></div></div>
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