ublas: reserve [Re: questions on ublas ?]

From: jhrwalter (walter_at_[hidden])
Date: 2001-12-08 07:23:50

--- In boost_at_y..., Toon Knapen <toon.knapen_at_s...> wrote:
> Peter Schmitteckert (boost) wrote:

[snip]
 
> Do you mean that you would first create a matrix of sufficient 
size, 
> then take a submatrix and resizing the latter does not need 
reallocation 
> as long as the size of the submatrix is not bigger as the size of 
the 
> original matrix. That would indeed cover the `quest for a minimal 
number 
> of reallocations`. But maybe that is what you meant Joerg (and I 
just 
> did not get your point).

matrix_range could do the job. But I don't know your application for 
matrix reallocations. Let's take some examples: if I'd have to 
implement LU-factorization in LAPACK style, I'd use matrix_range as a 
view on the sub matrices of the matrix to factorize. If I'd need 
Fortan like workspace, I'd eventually discuss size()/capacity().
 
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.
 
Regards
 
Joerg