[Dune] build a BCRSMatix C = A + B

[Markus Blatt]

Hi,

On Fri, Jul 31, 2015 at 10:51:24PM -0400, abdeladhim tahimi wrote:
> 
> I have 3 BCRSMatrix instances A, B and C
> A and B have different sparsity patterns given explicitly and C is the sum
> of A and B. Is there a way to C get built without having to define
> explicitly its sparcity pattern (deduce the sparcity pattern of C
> implicitly through its definition (C = A + B)?
>

No. You have to do this manually, e.g. by looping over the rows of A
and B and computing the union of the nonzero columns. The problem is
that it is hard to guess the total number of nonzeros and you might
need to do the loop twice.

But maybe the information is also given in another way implicitly?

Markus

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Dr. Markus Blatt - HPC-Simulation-Software & Services http://www.dr-blatt.de
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