[Trilinos-Users] Galeri, cartesian subdomains and overlapped maps

[Daniele Avitabile]

Hi all,

I have distributed the nodes of a 2D Cartesian grid (x and y directions, nx
and ny gridpoints respectively) on mx times my processors, in the same way
that Galeri does. Now, each processor contains nodes of a cartesian
subdomain.

I am in the process of writing an overlapped map for the nodes: say that
when I will be computing a first derivative in x

 ( u_{i+1,j} - u_{i,j} )/dx

I will have to make sure that node i+1 is contained in the overlapped map
*even when i lies on the boundary of the subdomain*.

Is there any smart/quick way to select the nodes at the boundary of the
cartesian subdomain and to create the overlapped map? Please note that in my
code I would *not* want to build a linear operator for the first derivative,
therefore I cannot use the columnMap() of such operator to infer the
overlapped map.

Best.

Daniele
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