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[Frama-c-discuss] an example involving floats

  • Subject: [Frama-c-discuss] an example involving floats
  • From: david.delmas at airbus.com (David DELMAS)
  • Date: Thu, 05 Mar 2009 19:44:06 +0100
Hello,

here is an apparently simple example :

/*@
assigns \nothing;
ensures E < A ==> \result == B;
*/
float F(float E, float A, float B)
{
    if (E < A) return B;
    else return 0.;
}

The postcondition is proved by Z3, Yices and CVC3, but neither by Alt-
Ergo, nor by Simplify.
(of course it is proved by all if I change the float type to int)

I would appreciate some intuition on the reason why it is so.

Thanks in advance,
David

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