[ublas] Iteration over non zero elements

From: Fred (hakonbh_at_[hidden])
Date: 2006-11-08 15:16:24

Hi,

I'm building one simple version of Gauss Elimination, but I would like to
iterate only over non zero elements.
I got an execution error pointing to the iterators. I think I can't explain
what is happening without post the code, so I copy it below.
Could you tell me if there's any problem with iteration in sparse
matrix/vector?
I wrote the code based on this
link<http://www.bauv.unibw-muenchen.de/%7Ewinkler/ublas/tuc/ublas/matrix_sparse_usage.html>(
http://www.bauv.unibw-muenchen.de/~winkler/ublas/tuc/ublas/matrix_sparse_usage.html
).

Thank you for your time,

Frederico B. Teixeira
-- 
Electrical Enginnering
UFMG, Brazil
CODE:
> typedef boost::numeric::ublas::compressed_matrix<double> sparse_matrix;
> typedef boost::numeric::ublas::vector<double> dense_vector;
>
> template <class Matrix>
> void gauss(std::size_t n, Matrix &A)  {
>     double m;
>     typedef sparse_matrix::iterator1 i1_t;
>     typedef sparse_matrix::iterator2 i2_t;
>
>     i1_t i1 = A.begin1();
>     i2_t i2;
>
>     for(int k=0;k<n-1;k++) {
>         for(int i=k+1;i<n;i++) {
>             m = A(i,k)/A(k,k);
>             i2 = i1.begin();
>             while(i2 != i1.end()) {
>                 A(i,i2.index2()) -= m*(*i2);
>                 i2++;
>             }
>         }
>         i1++;
>     }
> }
>