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From: James N. Knight (nate_at_[hidden])
Date: 2006-10-13 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 non-const 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.


>> 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
> )
> 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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