Re: [petsc-users] Equivalent of VecScatter for index sets

[Rémi Lacroix]

Le 13/01/2014 19:00, Matthew Knepley a écrit :
On Mon, Jan 13, 2014 at 9:47 AM, Rémi Lacroix <remi.lacr...@inria.fr 
<mailto:remi.lacr...@inria.fr>> wrote:

    Hello,

    I would like to permute an index set with another index set, just
    like you can do for vectors using VecScatter.

    I have two index sets IS1 and IS2 which share the same size but
    have different parallel layouts. I often need to permute
    vectors/matrices using those two index sets (as in first permute
    with IS1 then permute the result with IS2). Since I don't use the
    intermediate result, I would like to permute IS1 with IS2 to get a
    new index set so that I can permute directly my vectors/matrices
    with it. Is that possible using Petsc?


We do not have this particular composition in our interface. However, 
you could accomplish this using PetscSF.

  Thanks,

     Matt

Thanks for the quick answer.

So basically I need to have a look at the underlying mechanism of 
VecScatter and implement something similar for IS. How complex would it 
be in practice?

Rémi