<p>Dear Barry:</p><p>thank you for your reply. if the distribution of A11 and B is different, it will not work if I do B*A11? <br></p><p>Happy holiday:).</p><p>Regards,</p><p>Yujie</p><br><div class="gmail_quote">On Wed, Dec 24, 2008 at 11:15 AM, Barry Smith <span dir="ltr"><<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><br>
If you want the resulting A11, etc to have the same distribution as B then when you construct A you will<br>
have to construct it with the rows/columns from the 1 block interlaced with the 2 block. This means<br>
you would form A it would look<br>
a00 a0,n a0,1 a0,n+1 ...<br>
an,0 an,n an,1 an,n+1 ..<br>
a1,0 a1,n ...<br>
....<br><font color="#888888">
<br>
Barry</font><div><div class="Wj3C7c"><br>
<br>
<br>
On Dec 23, 2008, at 7:49 PM, Yujie wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi, PETSc Developer<br>
<br>
Now, I have two matrices, A and B. A (its dimension is 2N*2N) is MPIDense format. B (N*N) is MPIAIJ.<br>
<br>
I want to exact four matrices from A, like this<br>
<br>
A11 A12<br>
<br>
A=<br>
<br>
A21 A22<br>
<br>
each submatrices is multplied by B. My question is if A11, A12, A21, A22 have same distribution with B, how to do it with MatGetSubMatrix()?<br>
<br>
Thanks a lot.<br>
<br>
Regards,<br>
<br>
Yujie<br>
<br>
</blockquote>
<br>
</div></div></blockquote></div><br>