Re: negative values of Finite Domain Variables

[Salvador Abreu]

hi Daniel,

You can try with the negative domain variant; to do that 
(1) clone get the gprolog source (from github or sourceforge)
(2) in the GNU prolog src subdir, do:
    git switch negative-domains
    make distclean
    ./configure
    make
(3) you will have a version that can handle domains which range into negative 
values; a easy way to use it without installing system-wide is to continue with 
the commands:
    . SETVARS
(in the same directory)

here’s a transcript:

15:21:52$ . SETVARS 
15:21:54$ gprolog
GNU Prolog 1.5.0 (64 bits)
Compiled May 27 2022, 15:21:42 with gcc
Copyright (C) 1999-2022 Daniel Diaz

| ?- fd_domain(X,-100,100), 2 #= X + 9.

X = -7

yes
| ?- 

if you want to remain with the main branch, you need to remodel your problems 
to work with positive numbers only (e.g. with an offset).

hope this helps.
-spa


> On 27 May 2022, at 12:28, Daniel Ajoy <da.ajoy@gmail.com> wrote:
> 
> Hi,
> 
> I was expecting:
> 
> fd_domain(X,-100,100), 2 #= X + 9.
> 
> to produce
> 
> X  = -7
> 
> But it didn't find that answer. Is it the case that the FD variables can only 
> be positive?
> 
> If that's the case, is there a workaround?
> 
> Daniel
>