Re: ublas: reserve

From: jhrwalter (walter_at_[hidden])
Date: 2001-12-10 04:26:02

--- In boost_at_y..., Toon Knapen <toon.knapen_at_s...> wrote:
> > This is indeed an alternative. matrix_range should be an suited 
> > submatrix adaptor (with a poor name?). 
> 
> 
>  > [and in another thread]
>  > matrix_range is well suited to address a sub matrix of an 
existing
>  > matrix. But one has to consider carefully, what code a compiler 
emits
>  > with this additional indirection, AFAIK
> 
> 
> but matrix_range does not feature a resize(size_type,size_type).
> The idea would be that you can constantly resize the adaptor 
> (matrix_range) as long as it is smaller or equal in size to the 
matrix 
> it originates from.
 
I usually construct a new adaptor, for example:
 
matrix<double> m (size, size);
for (int i = 0; i < size; ++ i) {
    matrix_range<matrix<double> > mr (m, range (0, i), range (0, i));
    ...
}

>  > [and yet in another thread]
>  > Correct. matrix_range checks it's dimensions against the 
dimensions
>  > of the underlying matrix.
> I can't find that, the constructors e.g. looks like :
> 
>   NUMERICS_INLINE
>   matrix_range (matrix_type &data, const range &r1, const range 
&r2):
>      data_ (data), r1_ (r1), r2_ (r2) {}
 
Oops. The checks are deferred until element access or iterator 
dereference. Is that too late?
 
Regards
 
Joerg