Frama-C-discuss mailing list archives

This page gathers the archives of the old Frama-C-discuss archives, that was hosted by Inria's gforge before its demise at the end of 2020. To search for mails newer than September 2020, please visit the page of the new mailing list on Renater.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Frama-c-discuss] Problem with Jessie and float division

Le lundi 08 octobre 2012 ? 11:05 +0200, Boris Hollas a ?crit :
> Hello,
> 
> the code below doesn't verify with Jessie because 0.8 * x > 0.0 can't be 
> verified.
> 
> #pragma JessieFloatModel(math)
> 
> //@ requires 1 <= x < 10;
> void foo(int x) {
>    double y = 1.0 / (0.8 * x);
> }
> 
> 
> If I add
> //@ lemma pos: \forall integer x; x > 0 ==> 0.8 * x > 0.0;
> then this lemma can't be verified. This happens with Alt-Ergo and 
> Simplify and both the why2 and the why3-backend.

I don't understand what you think the issue is. Sure, alt-ergo and
simplify might no be powerful enough to prove the goal, but how does
that make it a problem with jessie and float division? In fact, cvc3,
z3, and gappa, succeed in proving your program.

Best regards,

Guillaume