[petsc-users] Accessing submatrices without additional memory usage

[Jed Brown]

Michał Dereziński <michal.derezinski at gmail.com> writes:

> Great! Then I have a follow-up question:
>
> My goal is to be able to load the full matrix X from disk, while at
> the same time in parallel, performing computations on the submatrices
> that have already been loaded. Essentially, I want to think of X as a
> block matrix (where the blocks are horizontal, spanning the full width
> of the matrix), 

What would be the distribution of the vector that this non-square
submatrix (probably with many empty columns) is applied to?

Could you back up and explain what problem you're trying to solve?  It
sounds like you're about to code yourself into a dungeon.
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