Re: [boost] Re: Re: Constrained genericity at last? (any interestinanoperator traits/concept traits library?)

From: Victor A. Wagner Jr. (vawjr_at_[hidden])
Date: 2004-09-27 03:02:45

At Sunday 2004-09-26 17:35, you wrote:
> > Victor A. Wagner Jr. <vawjr_at_[hidden]> wrote:
> > The midpoint between them is (this is legal using your constraints):
> >
> > a + (b-a)/2
> >
> > 1st year algebra teaches us that this is equivalent to:
> >
> > (a+b)/2
> >
> > While on most systems the intermediate value (a+b) would be useless, as
> > soon as you divide by 2 it again becomes useful.
> >
> > with a third pointer (T* c;):
> >
> > (a+b+c)/3
> >
> > becomes calculable and useful though clearly
>
>Just a small $0.02...
>
>(a + b) is a dangerous thing in a 32 bit world full of arithmetic
>overflow opportunities.  You'd have to have a very good reason for
>doing it this way I'd think.
>
>a + (a-b) / 2 is a bit safer

I don't see the safety issue and what you showed is incorrect; a + (b-a) / 
2   is at least correct, but b-a overflows just as readily as a+b

>matt
>matthurd_at_[hidden]
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Victor A. Wagner Jr.      http://rudbek.com
The five most dangerous words in the English language:
               "There oughta be a law"