Re: [boost] uBLAS formal review

From: Fernando Cacciola (fcacciola_at_[hidden])
Date: 2002-06-28 09:06:06

----- Original Message -----
From: "David Abrahams" <david.abrahams_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Thursday, June 27, 2002 8:23 PM
Subject: Re: [boost] uBLAS formal review

>
> From: "Fernando Cacciola" <fcacciola_at_[hidden]>
>
> > Not using valarray<> prevents fast 'memcpy' optimizations...
>
> valarray isn't the only route to those optimizations is it? Couldn't one
> equally say "not using std::copy() prevents fast 'memcpy'
> optimizations..."?
>
You are right, valarray<> isn't the only route for those optimizations.
What I meant to say -but I didn't- is that there are at least 3 different
ublas arrays all sharing a common internal array representation. It seems
reasonable to me to factor this out into a POD-optimized value-based array.
That's the purpose of valarray, isn't it?
I know nobody likes it (valarray), but at least as a concept it is precisely
up to this task (being used as the internal storage of a higher level array
data structure).
If valarray<> usual implementations can't be trusted, I would code a
valarray like, POD-optimized, class as part of ublas and use it. It doesn't
need much of the valarray<> interface, so it can be quite simple.

Fernando Cacciola
Sierra s.r.l.
fcacciola_at_[hidden]
www.gosierra.com