[petsc-users] Accessing submatrices without additional memory usage

[Matthew Knepley]

On Wed, May 24, 2017 at 1:09 AM, Michal Derezinski <mderezin at ucsc.edu>
wrote:

> Hi,
>
> I want to be able to perform matrix operations on several contiguous
> submatrices of a full matrix, without allocating the memory redundantly for
> the submatrices (in addition to the memory that is already allocated for
> the full matrix).
> I tried using MatGetSubMatrix, but this function appears to allocate the
> additional memory.
>
> The other way I found to do this is to create the smallest submatrices I
> need first, then use MatCreateNest to combine them into bigger ones
> (including the full matrix).
> The documentation of MatCreateNest seems to indicate that it does not
> allocate additional memory for storing the new matrix.
> Is this the right approach, or is there a better one?
>

Yes, that is the right approach.

  Thanks,

    Matt


> Thanks,
> Michal Derezinski.
>



-- 
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

http://www.caam.rice.edu/~mk51/
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