Hi, you could decompose the element constraint by posting implications instead, such as x=i implies y=a[i] for all i.
Regarding the rounding, you're right, your approach should work (and just using a channel directly forces the float var to take an integral value). Cheers, Guido -- GUIDO TACK Senior Lecturer Information Technology Monash University Level 6, Room 6.40, Building H, Caulfield Campus 900 Dandenong Road Caulfield East VIC 3145 Australia T: +61 3 9903 1214 E: guido.t...@monash.edu <mailto:guido.t...@monash.edu> http://www.csse.monash.edu/~guidot/ <http://www.csse.monash.edu/~guidot/> > On 21 Nov. 2016, at 6:02 am, Dani G <daniel.garcialore...@gmail.com> wrote: > > Hello all, > > These ares my first question, thanks for this library, I found it very > interesting and the tutorial is really great. > > I'm using the last version of Gecode 5.0. In the project I'm working on I > need to use float variables (the problem include exponential calculations > that need to be precise), although I'm trying to minimize their use as much > as possible by converting Floats into Into Ints. Two questions arises: > > - I couldn't find a "element" constraint for FloatVarArray, and it would > really help me. I don't know if I could easily reimplemented it using the > example of the constraint for Int variables, or there will be some problem? > Should I find a different modelling, like using a linear constraint using a > 0,1 vector? > > - To minimize the use of Float variables I want to round my Float > calculations using two digits and then convert them to Int using a channel > constraint. I imagine that I need to take into account the rouding if i want > to make it work. This sounds right? > > IntVar time; // Variable used in other constraints > FloatVar time_float(home, TIME_MIN, TIME_MAX); // conversion to float > > channel(home, time, time_float); // conversion to float for the calculations > > // float calculation, this will obviously wil be any float number > FloatVar activity_float= expr(home, c1 * exp( c2 * time_float); > > // Rounded version of activity multiplied by 100 to be converted into Int > FloatVar activity_float_rounded100(home, ACTIVITY_MIN, ACTIVITY_MAX); > > // Rounding up, and multiplying by 100 to keep the desired precision > rel(home, activity_float_rounded100 >= 100* activity_float); > rel(home, activity_float_rounded100-1 < 100* activity_float); > > IntVar activity_int(home, ACTIVITY_MIN, ACTIVITY_MAX); // rounded activity by > 100 > channel(home,activity_int, activity_float_rounded100); > > // now activity_int can be used in other int constraints > > I bellieve that if I apply directly the channel to activity_float, the > exponential constraint will fail as channel will force activity to be exactly > equal to the Int value, am I right? > > > Thank you very much your work and for your thoughts > > Best regards > > Daniel > > > _______________________________________________ > Gecode users mailing list > users@gecode.org > https://www.gecode.org/mailman/listinfo/gecode-users
_______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
