[PPL-devel] Another question

[Ezio Bartocci]

so for integral you mean integers ? So it mean that accept only
rational number in the set of Q ?

On Thu, May 3, 2012 at 11:10 PM, Enea Zaffanella <zaffanella at cs.unipr.it> wrote:
> On 05/03/2012 06:13 PM, Ezio Bartocci wrote:
>>
>> Dear PPL developers,
>>
>>        I forward the message that I sent to Roberto. Since he is
>> traveling, maybe some of you can help us...
>>
>> Thanks a lot
>>
>> Best Regards
>>
>> Ezio
>
>
>
> Hello Ezio.
>
> I suspect the main problem is in the right hand side of the line:
>
>
>>>                 lin_exp[j]+=single_point[m]*(*it);
>
> Here single_point[m] has type mpf_class.
> However, the PPL only supports *integral* coefficients.
>
> When a generator has non-integral coordinates, it can be expressed using
> integral coefficients and providing a common divisor.
>
> For instance, if you need to specify a point in 3d having coordinates
>  (1.5, 0.5, 2.5)
> you can express it as
>  (3, 1, 5) / 2
>
> In C++, something like the following:
>
>  Variable A(0);
>  Variable B(1);
>  Variable C(2);
>  Linear_Expression le = 3*A + B + 5*C;
>  ph.add_generator(point(le, 2));
>
> where the second argument to `point' is the divisor
> (that gets applied to all the coefficients of `le').
>
> Hope this helps.
>
> Regards,
> Enea.



-- 
Dr. Ezio Bartocci, Assistant Professor
Dependable Systems Group
Department of Computer Engineering
Faculty of informatics
TU Wien, Vienna University of Technology, Austria
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