From: boost (boost_at_[hidden])
Date: 2002-04-16 08:43:00
Salut,
On Tuesday 16 April 2002 11:24, Kresimir Fresl wrote:
> Since Joerg didn't reply, I will quote his earlier comment
> on this topic (thread: `slicing and ranges of matrices', Jan. 24th):
>
> ``I believe, that it's difficult to estimate the complexity of
> operations on such a view for sparse matrices (in other words: they
> could be rather inefficient). May be we currently should be more
> interested in some gather and scatter functionality for sparse
> matrices.''
>
At least you could test a simple class, were you implement the
element look up using your indices.
T& matrix_view< matrix< double > >::operator( const int index1, const int
index2 )
{
return matrix_reference( rows[index1], columns[index2] );
}
where matrix_view<> has a reference to a matrix, and the desired rows and
columns vectors a private members. Maybe the performance is sufficient,
since the access of the underlying (sparse) matrix is probably much more
expensive.
Best wishes,
Peter