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From: Kresimir Fresl (fresl_at_[hidden])
Date: 2002-04-08 04:06:28

Hi Joerg,

>>I noticed that you didn't change `vector_of_vector<>::clear()',
>>which also calls `clear()' of inner array.

> I missed that one. It doesn't seem to be correct, too.

>>But it works anyway
>>with `std::vector< std::vector<> >. I am puzzled.

> I'll look into this, thanks.

Well, the fact that my program didn't crash doesn't prove
that `vector_of_vector<>::clear()' was correct ;O).

> As the very_long_class_names should indicate, classes like vector_of_vector
> and sparse_vector_of_sparse_vector were mainly intended as a proof of
> concept, that one is able to adapt traditional C++ container of container
> (like std::vector<std::vector<> >) as a matrix format.

> Your proposed vector_of_sparse_vector is the only form of these, I could
> vaguely imagine to use in a production environment. But wouldn't you really
> prefer the traditional compressed storage format?

You are probably right. But maybe there are some libraries
(sparse solvers in particular) which expect vector_of_sparse_vector
format. I still have old Roldan Pozo's TNT library (version 0.7 from 1997)
where sparse matrices are implemented that way. (Newer versions
have only dense vectors and matrices, but the stated goal is to
integrate `Lapack++', `Sparselib++' and `IML++'. And although there
were no new developments for more than a year and a half, it
seems that Pozo will finally resume the work -- citation from
`': ``Note: TNT 1.0 release scheduled
for Summer 2002.'')



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