On Fri, Mar 13, 2009 at 12:48 PM, Ravi Kannan <span dir="ltr"><<a href="mailto:rxk@cfdrc.com">rxk@cfdrc.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br>
This is Ravi Kannan from CFD Research Corporation. One basic question on<br>
the ordering of linear solvers in PETSc: If my A matrix (in AX=B) is a<br>
sparse matrix and the bandwidth of A (i.e. the distance between non zero<br>
elements) is high, does PETSc reorder the matrix/matrix-equations so as to<br>
solve more efficiently. If yes, is there any specific command to do the<br>
above?</blockquote><div><br>You can reorder the matrix using the MatOrdering class.<br><br> Matt<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
Thanks<br>
Ravi<br>
<br>
<br>
<br>
-----Original Message-----<br>
From: <a href="mailto:petsc-users-bounces@mcs.anl.gov">petsc-users-bounces@mcs.anl.gov</a><br>
[mailto:<a href="mailto:petsc-users-bounces@mcs.anl.gov">petsc-users-bounces@mcs.anl.gov</a>]On Behalf Of Yixun Liu<br>
Sent: Friday, March 06, 2009 12:50 PM<br>
To: PETSC<br>
Subject: matrix assembling time<br>
<br>
<br>
Hi,<br>
Using PETSc the assembling time for a mesh with 6000 vertices is about<br>
14 second parallelized on 4 processors, but another sequential program<br>
based on gmm lib is about 0.6 second. PETSc's solver is much faster than<br>
gmm, but I don't know why its assembling is so slow although I have<br>
preallocate an enough space for the matrix.<br>
<br>
MatMPIAIJSetPreallocation(sparseMeshMechanicalStiffnessMatrix, 1000,<br>
PETSC_NULL, 1000, PETSC_NULL);<br>
<br>
Yixun<br>
<br>
<br>
</blockquote></div><br><br clear="all"><br>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener<br>