[Gecode] Overflow problem in mult

[Christian Schulte]

Thanks for the info. I'll fix it...

Christian

--
Christian Schulte, http://www.imit.kth.se/~schulte/ 

-----Original Message-----
From: gecode-bounces at ps.uni-sb.de [mailto:gecode-bounces at ps.uni-sb.de] On
Behalf Of Guido Tack
Sent: Wednesday, May 19, 2004 9:42 AM
To: gecode at ps.uni-sb.de
Subject: [Gecode] Overflow problem in mult


Hi!

The mult propagator doesn't seem to be aware of overflows. 

E.g. this line
    GECODE_CME_PROP(x2 <= Arith::max(x0.min()*x1.min(),x0.max()*x1.max()));

clearly produces bogus results if x0.min==x1.min==0 and 
x0.max==x1.max>(INT_MAX/2), because then x0.max*x1.max will overflow and 
become < x0.min*x1.min.

-- 
Guido Tack
Programming Systems Lab
http://www.ps.uni-sb.de/~tack
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