[petsc-dev] Getting "from" and "to" IS from a VecScatter

[Barry Smith]

  Why do you need them? Maybe there is a better way?


On Jun 20, 2012, at 6:19 PM, Blaise Bourdin wrote:

> Hi,
> 
> I need to reconstruct the IS that were used to build a VecScatter between a local and a global Vec. 
> 
> From what I see in VecScatterView_MPI (vpscat.c:13), it looks like I can get the indices from from->local.vslots[i],to->local.vslots[i], i=0 .. i<to->local.n where from and to are obtained with
>  VecScatter_MPI_General *to=(VecScatter_MPI_General*)ctx->todata;
>  VecScatter_MPI_General *from=(VecScatter_MPI_General*)ctx->fromdata;
> 
> From there, constructing the IS is trivial. Is there a way that does not involve poking inside the VecScatter data structure?
> 
> Blaise
> 
> 
> -- 
> Department of Mathematics and Center for Computation & Technology
> Louisiana State University, Baton Rouge, LA 70803, USA
> Tel. +1 (225) 578 1612, Fax  +1 (225) 578 4276 http://www.math.lsu.edu/~bourdin
> 
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