[petsc-users] Some confusion about the vec tutorial ex8.c

[Matthew Knepley]

On Mon, May 27, 2013 at 12:18 AM, 丁老师 <ztdepyahoo at 163.com> wrote:

>   In ex8.c, ISLocalToGlobalMappingCreate usd the "ng" as the number of
> local element. 'ng' is te local size plus 2 ghost positions. But we create
> the vector x with VecCreate, x does not has ghost points.
>    how to explain this mapping.
>

1) Global vectors have no ghost points

2) We declare that this vector will have 2 ghost points for the example

   Matt


-- 
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
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