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 16:16:31

Gordon Woodhull wrote:
> 
> On Dec 10, 2008, at 7:24 AM, Johan Råde wrote:
>> 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?
> 
> Nope, as John pointed out later in his message, if the test is x<=y and 
> x is just slightly greater than y, then x can flip either way.

The statement is
"x <= y before truncation implies x <= y after truncation".
(Note the word "implies", not "equivalent to".)
The example you mention is not a counter-example to that statement.

--Johan Råde