Re: Everything You Know Is Wrong

[vincent.diemunsch@gmail.com]

Le lundi 29 février 2016 13:14:09 UTC+1, Jacob Sparre Andersen a écrit :

> Some of the rules which (apparently) aren't wrong yet:
> 
>    http://www.cse.msu.edu/~cse320/Documents/FloatingPoint.pdf
> 
> Greetings,
> 
> Jacob

Very interesting ! 
Here is the point about Ada : 

Remarkably enough, some languages don't clearly specify that if x is a
floating-point variable (with say a value of 3.0/10.0), then every occurrence
of (say) 10.0*x must have the same value. For example Ada, which is based
on Brown's model, seems to imply that floating-point arithmetic only has to
satisfy Brown's axioms, and thus expressions can have one of many possible
values. Thinking about floating-point in this fuzzy way stands in sharp
contrast to the IEEE model, where the result of each floating-point operation is
precisely defined. In the IEEE model, we can prove that (3.0/10.0)*10.0
evaluates to 3 (Theorem 7). In Brown's model, we cannot.

Maybe this could be a topic for a new revision of Ada ?

Kind regards,

Vincent