Re: [Help-gsl] Can I create a symmtric matrix?

[Shixin Zeng]

Brian Gough wrote:

> Shixin Zeng writes:
> >    I'm writing a FEM(Finite Elements Mothed) program using gsl to do 
> > matrix/vector operations.
> >    For the matrix is very big and symmetric, so I'm wondering if there 
> > is a way to create a symmetric matrix? I've read the manual, but I can't 
> > find any functions to do so.
>
> The raw CBLAS functions have support for packed (symmetric) matrices.
>  
What do you mean by "support"?  I guess you mean that CBLAS functions 
get/set elements of matrix merely via _get/_set functions, rather than 
visit the memory occupied by that element directorly, so if I implement 
myself _get/_set methods of matrices, then CBLAS will work fine, is it?

> GSL matrices don't have this, but you could define a few _get/_set
> packed access functions for such matrices.
>
>  
Could you give me some examples?
Could I do it like this?

typedef struct {
     gsl_matrix m;
} my_sym_matrix;

my_sym_matrix* *my_sym_matrix_alloc*(size_t, size_t);
double *my_sym_matrix_get* /(const gsl_matrix * m, size_t i, size_t j);
/void *my_sym_matrix_set* /(gsl_matrix * m, size_t i, size_t j, double x);
/|void|/| |/*my_sym_matrix_free*/(my_sym_matrix *m);

/Then, just treat my_sym_matrix as gsl_matrix for other operations?
But how CBLAS/gsl functions invoke my_sym* functions?

Thanks for your reply.

Best regards
Shixin Zeng