
Ublas : 
From: James N. Knight (nate_at_[hidden])
Date: 20061013 01:35:37
Thanks for the reply. I'm going think more about a block matrix structure.
I think this is a nice approach and should be easy to add to the ublas framework.
I'll post some code if I get something working.
I need to think about how exactly to store the submatrices of a matrix. If the block
matrix is const then references to sublocks can be stored. If its not const, should we
copy the submatrices into the matrix or use nonconst references and thus change the sub
matrices when we change the block matrix.
Beyond this I think it is a matter of correctly specifying the operators and iterators.
This will take some work as well, but it should be feasible.
Thanks again.
Nate
>> Is there any interest in something like this?
> Actually once I thought that I am in a big need to have
> concat operation in my code (I work mainly on FEM and BEM codes).
> But then I saw that people use block matrices instead of concatination
> (see for example
> http://www.dealii.org/developer/doxygen/deal.II/classBlockMatrixBase.html
> )
> and that's work fine.
> Anyway, it would be nice to see what gain can be obtained from use
> of (effectively implemented) concatenation.
>
> Additionally I see another problem: If you have a concatination
> ET (a sparse one), how do you effectively construct a sparse matrix
> from that expression ? What kind of sparsity pattern does the
> concatinated ET have (CSR or CSC or "sorted list of triples"),
> given that it's arguments differ in their sparsity patterns.
>
> Regards, hope this helps,
> Dima.
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