Re: Multiplication

Hi Glauber,

On Wed, Aug 29, 2001 at 08:32:52PM +0000, Glauber Jose Vaz wrote:
> I'm using ECLiPSe version 5.1.1 and I think there is something wrong with this:
> 
> ?- use_module(library(fd)), A :: -2 .. 6, X :: 0 .. 1, T :: 0 .. 4, T #= A * X.
> T = T{[0..4]}
> A = A{[0..6]}
> X = X{[0, 1]}
> 
> Note that the variable A had its domain reduced.
> As X can be zero, the domain of A should not be reduced.
> 
> Why does it happen?

Yes, this is a bug in FD.  It doesn't handle properly the combination of
division by zero and negative numbers.

Unfortunately for you, we are in the process of replacing the existing
FD library, which means fixing bugs in it are a relatively low
priority.  And the nature of this one is such that it will take a lot of
time to make sure that, in fixing it, we don't introduce more bugs.
Given that we plan to throw this code away soon, spending nontrivial
amounts of time on it seems a waste of our (quite modest) resources.

I suggest you try to work around the problem.  If you have trouble doing
this, feel free to mail us with a description of what you're trying to
do, and we'll see if we can offer any advice.

Cheers,
Warwick