Re: Everything You Know Is Wrong

[vincent.diemunsch@gmail.com]

Le mercredi 2 mars 2016 15:33:18 UTC+1, Dmitry A. Kazakov a écrit :
> 
> IEEE model is wrong and Ada 83 model is right being closer to the interval computations.

Could you elaborate or give me a link to papers ?

> 
> BTW, it is advisable to always turn the IEEE semantics off. E.g. not to 
> use Float but
> 
>     subtype Proper_Float is Float range Float'Range;
> 
> instead. This saves a lot of debugging later.

Why is the IEEE semantics involved if the Ada model doesn't follow IEEE model ?
And what is the difference between the Proper_Float and the Float ?

> 
>  From the computational, rounding error control, engineering, etc POVs 
> there is no reason to suggest that (x/y)*y=x should hold for 
> floating-point numbers. They are not reals and cannot be reals. The 
> model must sacrifice some less important properties like (x/y)*y=x 
> (which is wrong for any measured values anyway) for more important ones 
> like rounding errors control, performance, optimization.

I can accept this. The sensible point for me is to be able to prove un upper bound to rounding errors.

Regards,

Vincent