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Ublas : |
From: Regis Behmo (regisb_at_[hidden])
Date: 2007-09-04 04:16:27
On 9/4/07, Karl Meerbergen <Karl.Meerbergen_at_[hidden]> wrote:
> Hi Regis,
>
> The choice of sparse matrix depends on what you want to do with it.
> For example, adding elements in any order is more efficient with
> coordinate_matrix than with compressed_matrix.
> A matrix times vector product is more efficient with the
> compressed_matrix format.
Okay, so I think the type I need is a coordinate_matrix.
> Gunter has a webpage with timings on the choice of format in function of
> the algorithm.
Are you talking about this page?
http://www.bauv.unibw-muenchen.de/~winkler/ublas/sparse_comparison.html
I'll wait until it comes online again.
> All is application dependent: in my finite element applications, I
> usually first create the sparse matrix structure in coordinate format,
> then create a compressed_matrix from that for use with a matrix vector
> product and other algorithms.
>
> The disadvantage of a mapped_matrix is that you are not going to be able
> to create matrices of large dimension. I guess this is still the case?
Yes, indeed, I want to use large dimension matrices. Why aren't
mapped_matrices adapted to this?
> To come to your question of removing a row/column from a sparse matrix:
> I would do this by manipulating the index1_data(), index2_data(), and
> value_data() of the matrix. But you need to be familiar with sparse
> matrix formats to be able to do this swiftly. Unfortunately, I do not
> have the time to write such routines for you.
Yes, I understand. Is there any documentation at all concerning these
methods on the web? I googled "index1_data
site:http://www.boost.org/libs/numeric/ublas/" and didn't get any
result.
Régis