Boost logo

Boost :

From: Kresimir Fresl (fresl_at_[hidden])
Date: 2002-04-16 04:24:21

Toon Knapen wrote:

> I'm looking for taking a view of a ublas matrix. What I mean is soth like :
> matrix< double > a(10,10);
> size_t row_indices[] = { 0, 3, 4, 9 };
> size_t column_indices[] = { 2, 3, 7 };
> matrix_view< matrix< double > > view( a,
> row_indices, row_indices + 4,
> column_indices, column_indices + 3 )
> to give me a 4*3 alias to the original matrix containing rows 0,3,4,9 and
> columns 2,3,7. Thus view(0,0) == a(0,2)
> AFAIK soth similar is not possible at the moment (if it is, please let me
> know) so I guess I'll give it a shot to implement it in ublas.

I am very interested in this functionality, so, yes, shoot ;o)

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



Boost list run by bdawes at, gregod at, cpdaniel at, john at