Re: [boost] [review][constrained_value] Review of Constrained Value Library begins today

Subject: Re: [boost] [review][constrained_value] Review of Constrained Value Library begins today
From: Johan Råde (rade_at_[hidden])
Date: 2008-12-10 07:24:05

Thorsten Ottosen wrote:
> 
> John Maddock gave two examples: one where we accapted wrong values and 
> one where we rejected correct values. I found the latter somewhat better 
> (because the invariant of bounded_float would be preserved), and if we 
> are able to get that behavior consistently, I would be quite happy.
> 
> So maybe most of our problems will be fixed by using >= and <= instead 
> of < and >?
> 
> -Thorsten
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Is the following true: if x and y satisfy  x <= y (or x >= y)
then they will still do so after any truncation from 80 to 64 bits?

Then, as Thorsten suggests, <= and >= will never erroneously accept any value.

We could then maybe implement < and > using <=, >= and the std::nextafter function,
and achieve the same guarantee there.

--Johan Råde