[petsc-users] Index set with zero size

[Jed Brown]

On Tue, Nov 9, 2010 at 12:11, Tim Kroeger
<tim.kroeger at cevis.uni-bremen.de>wrote:

> Is it allowed to work with an index set (IS) with size 0?
>

Yes.

In particular, using such an index set in VecScatter and MatGetSubMatrix, I
> am creating the following objects:
>
> v : a vector of size n>0,
> w : a vector of size 0,
> A : a matrix of size n\times0.
>
> Then I do
>
> MatMultAdd (A, w, v, v);
>
> This actually seems to change the value of v, although I supposed it not to
> do so.
>

It sounds like you have a simple test case for this, could you send it?

Jed
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