[petsc-users] precise meaning of SAME_NONZERO_PATTERN in MatAXPY?

[Matthew Knepley]

On Tue, Mar 12, 2013 at 5:56 AM, Frederik Treue <frtr at fysik.dtu.dk> wrote:

> Hi,
>
> what, exactly, does the the matstructure parameter to (e.g.) MatAXPY do?
> If the two matrices come from the same dm, ie. have the same stencil, is
> SAME_NONZERO_PATTERN then _guaranteed_ to work? Or does the routines
> actually depend on the actual value of the matrices being zero/non-zero,
> even inside the stencil?


It only concerns the nonzero pattern, not actual values. If two Mats come
from
the same DM with the same parameters, they have the same pattern.

  Thanks,

    Matt


>
> /Frederik Treue
>
>


-- 
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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