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Thanks! I will try this.<br>
<br>
Tabrez<br>
<br>
On 01/15/2013 12:23 PM, Jed Brown wrote:
<blockquote
cite="mid:CAM9tzSkWvjs1G=M3t8hhr7m9HNOYXiFDe9YqgDEbXw3sZ1dgkg@mail.gmail.com"
type="cite">
<div dir="ltr">On Tue, Jan 15, 2013 at 12:09 PM, Tabrez Ali <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:stali@geology.wisc.edu" target="_blank">stali@geology.wisc.edu</a>></span>
wrote:<br>
<div class="gmail_extra">
<div class="gmail_quote">
<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 text="#000000" bgcolor="#FFFFFF"> Jed<br>
<br>
The problem with MatGetSubMatrix is that iscol isn't
available easily. I want to get all associated columns
but according to the man page it is not possible in
Fortran.<br>
<br>
"If iscol is PETSC_NULL then all columns are obtained
(not supported in Fortran)."<br>
</div>
</blockquote>
<div><br>
</div>
<div style="">Well, we could add Fortran support for that
case (it currently needs a custom binding to do that) or
you can</div>
<div style=""><br>
</div>
<div style="">call
MatGetColumnOwnershipRange(A,colstart,colend,ierr)</div>
<div style="">ncols = colend - colstart</div>
<div style="">call
ISCreateStride(comm,ncols,colstart,one,iscol,ierr)</div>
<div style=""><br>
</div>
<div style="">and pass iscol to MatGetSubMatrix(). This is
what's done internally when you pass iscol=NULL:</div>
<div style=""><br>
</div>
<div style="">
<div> if (!iscol) {</div>
<div> ierr =
ISCreateStride(((PetscObject)mat)->comm,mat->cmap->n,mat->cmap->rstart,1,&iscoltmp);CHKERRQ(ierr);</div>
<div><br>
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<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 text="#000000" bgcolor="#FFFFFF"> <br>
Is there a workaround?<span class=""><font
color="#888888"><br>
<br>
Tabrez</font></span>
<div>
<div class="h5"><br>
<br>
On 01/14/2013 03:38 PM, Jed Brown wrote:
<blockquote type="cite">
<div dir="ltr">On Mon, Jan 14, 2013 at 3:27 PM,
Tabrez Ali <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:stali@geology.wisc.edu"
target="_blank">stali@geology.wisc.edu</a>></span>
wrote:<br>
<div class="gmail_extra">
<div class="gmail_quote">
<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">Hello<br>
<br>
I am solving a system of equations of the
form:<br>
<br>
|A C| |u1| = |f1|<br>
|C'B| |u2| |f2|<br>
<br>
After each solve, I need to perform B*f2
before updating f. Should I use
MatGetSubMatrix/VecGetSubVector followed
by MatMult or is there something simpler.<br>
</blockquote>
<div><br>
</div>
<div>Yes, or let PCFIELDSPLIT do all the
block solver stuff for you.</div>
</div>
</div>
</div>
</blockquote>
<br>
<br>
</div>
</div>
<div class="im">
<pre cols="72">--
No one trusts a model except the one who wrote it; Everyone trusts an observation except the one who made it- Harlow Shapley</pre>
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