EXTERNAL: Re: MatGetArray() not supporting Mat type mpiaij.

[Stephen R Ball]

I am using PETSc via the Fortran interface. I don't think MatGetOwnershipRanges() is available via Fortran.

 

________________________________________
From: owner-petsc-users at mcs.anl.gov [mailto:owner-petsc-users at mcs.anl.gov] On Behalf Of Dave May
Sent: 04 June 2008 13:43
To: petsc-users at mcs.anl.gov
Subject: EXTERNAL: Re: EXTERNAL: Re: MatGetArray() not supporting Mat type mpiaij.

You could use MatGetOwnershipRanges()
http://www-unix.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatGetOwnershipRanges.html
and then traverse the list "ranges[]" to determine which rank owns the global row number of interest.

Cheers,
    Dave
On Wed, Jun 4, 2008 at 9:33 PM, Stephen R Ball <Stephen.R.Ball at awe.co.uk> wrote:
Ok, I am looking into using MatGetRow(). However this requires the
global row number for input. I was looking to use MatGetOwnershipRange()
to obtain the range of global row numbers owned by each processor but
the documentation states that this routine assumes that the matrix is
laid out with the first n1 rows on the first processor, the next n2 rows
on the second, etc and that for certain parallel layouts this range may
not be well defined.

This is the case for me. Do you have a routine where I can specify a
global row number and it will tell me the rank of the processor that
owns it? This is to ensure that MatGetRow() only gets called by the
owner processor for each global row number.

Regards

Stephen


-----Original Message-----
From: owner-petsc-users at mcs.anl.gov
[mailto:owner-petsc-users at mcs.anl.gov] On Behalf Of Matthew Knepley
Sent: 03 June 2008 15:29
To: petsc-users at mcs.anl.gov
Subject: EXTERNAL: Re: MatGetArray() not supporting Mat type mpiaij.

On Tue, Jun 3, 2008 at 8:11 AM, Stephen R Ball
<Stephen.R.Ball at awe.co.uk> wrote:
> Hi
>
> I have been trying to extract an array containing the local matrix
> values using MatGetArray() via the Fortran interface but get the error
> message that Mat type mpiaij is not supported with this routine. All I
> want to do is to extract the local matrix values so that I can output
> them to file in the format I want rather than via use of the MatView()
> routine. Can you suggest a way of how I can go about extracting the
> local matrix values?

This is no "local matrix". The Mat interface is supposed to be data
structure
neutral so we can optimize for different architectures. If you want the
values
directly, I would use MatGetRow() for each row.

 Matt

> Thanks
>
> Stephen
>
>



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What most experimenters take for granted before they begin their
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