[petsc-users] MAT_REUSE_MATRIX

[Matthew Knepley]

On Mon, May 10, 2010 at 12:07 PM, <irfan.khan at gatech.edu> wrote:

> Hi Petsc Team,
>
> When using the subroutine MatMatMult(Mat A,Mat B,PetscReal fill,Mat *C)
> with option MAT_REUSE_MATRIX, Can the C matrix be any one of A or B?
>

I do not think that is safe. I believe C needs to be another matrix, but it
can be
reused for successive multiplies.

  Matt


> Thank you
> Irfan
>
> ----- Original Message -----
> From: "Matthew Knepley" <knepley at gmail.com>
> To: "PETSc users list" <petsc-users at mcs.anl.gov>
> Sent: Friday, May 7, 2010 4:03:42 PM GMT -05:00 US/Canada Eastern
> Subject: Re: [petsc-users] Adding MatAij rows
>
> On Fri, May 7, 2010 at 3:57 PM, < irfan.khan at gatech.edu > wrote:
>
>
>
>
>
>
> Petsc Team,
>
> Is there a function that can be used to add two rows and put the results
> into a third row of the same parallel matrix (MPIAIJ)? i.e
>
> A[k][l] = A[i][l] + A[j][l]
>
>
>
> No, since it would entail messing with the nonzero structure. You could
> easily
> use a second matrix to get this effect from subsequent MatMult() calls.
>
>
> Matt
>
>
>
>
>
> Thank you
> Irfan
>
> --
> PhD Candidate
> G.W. Woodruff School of Mechanical Engineering
> Georgia Institute of Technology
> Atlanta, GA (30332)
>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
>
> --
> PhD Candidate
> G.W. Woodruff School of Mechanical Engineering
> Georgia Institute of Technology
> Atlanta, GA (30332)
>



-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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