On 20.05.2012, at 13:54, Nicolas Cellier wrote:

> I posted in inbox in order to obtain an agreement on features, rather
> than begging for beta-testers.

Ah. Well, my needs are modest: I want to be able to print floats precisely, and up to a given precision. Storing should match reading so a repeated store/read does not change the value. I leave the details to people more knowledgable in that area, such as you :)

- Bert -

> For testing, Burger & Dybvig papers report that a set of 250 680 float
> was used and compared to various libc printf (the linux and solaris
> one were rounding correctly, the SGI, HP, RS6000 and Dec Alpha all
> suffered from some incorrect rounding at time of writing).
> We should really have such intensive tests, but maybe make them optional...
> 
> With our rational arithmetic, we can also test correct rounding
> without a reference to external library :
> 1) we produce a printed representation
> 2) we re-interpret the printed representation in rational arithmetic
> 3) we test (original asTrueFraction - reconstructed) abs <= (original
> ulp / 2) for free format
> 4) we test (original asTrueFraction - reconstructed) abs <= (((base
> raisedTo: placesDesired) reciprocal max: original ulp) / 2) for fixed
> format
> 
> But 2 bugs in printing and scanning could eventually compensate...
> Testing that printed representation is the shortest form having this
> property is a bit more involved...
> 
> Nicolas
> 
> 2012/5/20 Bert Freudenberg <bert at freudenbergs.de>:
>> Looks good to me - but I doubt you will get any testing unless you actually commit to trunk :)
>> 
>> - Bert -