Dear Laura Cattaneo,
Your code indeed should work and modify the Mbar matrix.
To be a liitle bit mor efficient, you could take non const iterators and
replace the last line by
*it_nz /= sum_row;
Of course, when you iterate on a sparse vector and modify it, you have
to care that the structure of the sparse vector is not modified (add or
delete nonzero elements). Because in that case, the iterators are
nolonger valid. In you case, this is ok.
Yves.
Le 31/10/2012 09:06, laura cattaneo a écrit :
> Dear all,
> I want to modify some values stored into a matrix, but I can't do it.
>
> If I try to excute these lines of code:
>
>
> typename gmm::linalg_traits<MAT>::const_sub_row_type
> row = mat_const_row(Mbar,i);
> gmm::linalg_traits< gmm::rsvector<scalar_type> >::const_iterator
> it_nz = vect_const_begin(row);
> gmm::linalg_traits< gmm::rsvector<scalar_type> >::const_iterator
> ite_nz = vect_const_end(row);
> for (; it_nz != ite_nz ; ++it_nz) {
> Mbar(i, it_nz.index()) = (*it_nz)/sum_row;
> }
>
> the values inside the Mbar matrix don't change and I don't understand why.
>
> Some one can help me??
>
> The MAT type is
>
> typedef gmm::rsvector<scalar_type> sparse_vector_type;
> typedef gmm::row_matrix<sparse_vector_type> sparse_matrix_type;
>
>
> Thanks
>
> Laura Cattaneo
>
>
>
>
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--
Yves Renard ([email protected]) tel : (33) 04.72.43.87.08
Pole de Mathematiques, INSA-Lyon fax : (33) 04.72.43.85.29
20, rue Albert Einstein
69621 Villeurbanne Cedex, FRANCE
http://math.univ-lyon1.fr/~renard
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