On Nov 18, 2007 12:21 PM, Tim Stitt <timothy.stitt@xxxxxxxx> wrote:
Oh...ok I am now officially confused.
I have developed a serial code for getting the first k rows of an
inverted sparse matrix..thanks to PETSC users/developers help this past
week.
In that code I was calling MatLUFactorSymbolic() and
MatLUFactorNumeric() to factor the sparse matrix and then calling
MatSolve for each of the first k columns in the identity matrix as the
RHS. I then varied the matrix type from the command line to test MUMPS,
SUPERLU etc. for the best performance.
Now I just want to translate the code into a parallel version...so I now
assemble rows in a distributed fashion and now working on translating
the MatLUFactorSymbolic() and MatLUFactorNumeric() calls which require
index sets...hence my original question.
Are you saying that I now shouldn't be calling those routines?
You can certainly do it that way, but it is much easier to just use a KSP.
You set the Mat using KSPSetOperators, then KSPSetType(ksp, KSPPREONLY),
and PCSetType(pc, PCLU) (or MUMPS or whatever). Then KSPSolve() with the
identity columns. We handle everything else.
Matt
Tim.
Matthew Knepley wrote:
On Nov 18, 2007 11:52 AM, Tim Stitt <timothy.stitt@xxxxxxxx> wrote:
Matt,
It is in setup for MatLUFactorSymbolic() and MatLUFactorNumeric() calls
which require index sets. I have distributed my rows across the
processes and now just a bit confused about the arguments to the
ISCreateGeneral() routine to set up the IS sets used by the Factor
routines in parallel.
So my basic question is what in general is the length and integers that
get passed to ISCreateGeneral() when doing this type of calculation in
parallel? Are they local index values (0..#rows on process-1) or do they
refer to the distributed indices of the global matrix?
To be consistent, these would be local sizes and global numberings. However,
I am not sure why you would be doing this. I do not believe any of the parallel
LU packages accept an ordering from the user (they calculate their own),
and I would really only use them from a KSP (or PC at the least).
Matt
Tim.
Matthew Knepley wrote:
On Nov 18, 2007 11:34 AM, Tim Stitt <timothy.stitt@xxxxxxxx> wrote:
OK..so I should be using the aggregate length returned by
MatGetOwnershipRange() routine?
If you are using it to permute a Mat, yes.
Matt
Thanks Matt for you help.
Matthew Knepley wrote:
IS are not really parallel, so all the lengths, etc. only refer to local things.
Matt
On Nov 18, 2007 11:22 AM, Tim Stitt <timothy.stitt@xxxxxxxx> wrote:
Hi all,
Just wanted to know if the "the length of the index set" for a call to
ISCreateGeneral() in a parallel code, is a global length, or the length
of the local elements on each process?
Thanks,
Tim.
--
Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
HPC Application Consultant - ICHEC (www.ichec.ie)
Dublin Institute for Advanced Studies
5 Merrion Square - Dublin 2 - Ireland
+353-1-6621333 (tel) / +353-1-6621477 (fax)
--
Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
HPC Application Consultant - ICHEC (www.ichec.ie)
Dublin Institute for Advanced Studies
5 Merrion Square - Dublin 2 - Ireland
+353-1-6621333 (tel) / +353-1-6621477 (fax)
--
Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
HPC Application Consultant - ICHEC (www.ichec.ie)
Dublin Institute for Advanced Studies
5 Merrion Square - Dublin 2 - Ireland
+353-1-6621333 (tel) / +353-1-6621477 (fax)
--
Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie>
HPC Application Consultant - ICHEC (www.ichec.ie)
Dublin Institute for Advanced Studies
5 Merrion Square - Dublin 2 - Ireland
+353-1-6621333 (tel) / +353-1-6621477 (fax)