Re: questions on ublas ?

From: jhrwalter (walter_at_[hidden])
Date: 2001-12-07 02:36:07

--- In boost_at_y..., Toon Knapen <toon.knapen_at_s...> wrote:
> jhrwalter wrote:
> 
> >>what's the complexity guarantee of `resize`. I guess it is 
intended 
> >>to reshape a matrix without having to allocate memory. 
> >  
> > If possible, yes (the actual implementations are occasionally 
> > suboptimal ;-). It's an open question, whether there is need for 
a 
> > similar operation which conserves matrix data. Complexity 
guarantees 
> > depend on operator new, but should be quadratic.
> >  
> > 
> >>For instance if I 
> >>need a temporary matrix in a loop, but in every loop the total 
size 
> >>of the matrix can be different, I can allocate a matrix with some 
> >>maximal size and resize it in every loop to something smaller in 
every  
> >>loop in constant amortised time ?
> >>
> > 
> > Currently not, but it should be possible to change this. May be 
we 
> > need to differentiate size() and capacity()?
> 
> Definitly. This would minimise memory allocation !

Agreed.
 
[snip]
 
> > Bonus question: what's the best namespace name?
> 
> I guess you mean the namespace for the whole ublas package ? boost 
or 
> boost::numerics I guess.

I recently noticed a thread, which discussed, if namespace names 
shouldn't be abbreviated (like std ;-). The only abbreviation for 
numerics that I can come up is 'num'. But I don't like it very much.
 
[snip]
 
> >>In that case I'm going to deploy it in my own projects ASAP ! 
Nice !
> >>
> >  
> > Sorry, we're not as fast ;-)
> I would be interested in doing it myself (with a little support of 
course)
> 
> if you think it's feasible.
 
Sparse matrix integration is clearly delicate, especially w.r.t. 
iterators. I'm not sure, if this wouldn't be too early.
 
Regards
 
Joerg