After several tests, it seems in fact that it is a rounding issue : several combinations of the parameters give an identical result if printed. I will check further if there is no bug in my code, but it seems that is not a Gecode problem. Thanks.
Le 28/05/13 22:47, Christian Schulte a écrit : > Yes, that was also my suspicion: maybe it is a rounding issue. > > > > Best > > Christian > > > > -- > > Christian Schulte, www.ict.kth.se/~cschulte/ > > > > *From:*users-boun...@gecode.org [mailto:users-boun...@gecode.org] *On > Behalf Of *Guido Tack > *Sent:* Tuesday, May 28, 2013 10:45 PM > *To:* Pascal Francq > *Cc:* users@gecode.org > *Subject:* Re: [gecode-users] Consecutive instances of Gecode produce > different results > > > > The propagator looks ok (waiting for all variables to be assigned is > definitely monotonic). I think I'd add some debugging output to your > propagate function, printing the v and l arrays and the resulting Cost > whenever it is computed successfully. Perhaps that at least gives you > an idea if the integer variables are already different or if it's the > floating point computation. > > > > Cheers, > > Guido > > > > -- > > Guido Tack > > http://www.csse.monash.edu/~guidot/ > > > > > > > > On 24/05/2013, at 6:51 AM, Pascal Francq (Mailing lists) > <mailing-l...@francq.info <mailto:mailing-l...@francq.info>> wrote: > > > > 1. My propagator is very simple : It waits until all v and I are > assigned. Then, it computes a cost function (to optimize) depending from > these variables. > > > //----------------------------------------------------------------------------- > PropCost RChoquetPropagator::cost(const Space&, const ModEventDelta&) const > { > return PropCost::binary(PropCost::HI); > } > > //----------------------------------------------------------------------------- > ExecStatus RChoquetPropagator::propagate(Space& home, const ModEventDelta&) > { > if((!v.assigned())||(!I.assigned())) > return (ES_NOFIX); > double Res(Compute(*this)); // Make some computation > if(Res<-1.0||Res>1.0) > throw std::range_error("Cost function must be in > [-1,1]"); > if(Cost.eq(home,Res)==Float::ME_FLOAT_FAILED) > return ES_FAILED; > return home.ES_SUBSUMED(*this); > } > > 2. I don't have program any parallel searches. > > I will check 22.9 in MPG (for the moment, I relaunch the program several > times rather than calling a function multiple times in the same program > run). > > Le 23/05/13 21:27, Christian Schulte a écrit : > > Oh, I see. That means that there is most likely a bug (could also be ok) in > your own propagator. > > Normally, a propagator must be monotonic: it never propagates more when it > is run on bigger variables domains. Or with other words: the smaller the > domains the more it propagates. > > Some propagation algorithms do not follow this which might lead to > indeterminstic behavior as you observed. Check 22.9 in MPG. > > But most likely it is a bug in your propagator. > > Or do you use parallel search with several threads? This can also lead to > non-deterministic behavior. > > Cheers > Christian > > -- > Christian Schulte, www.ict.kth.se/~cschulte/ > <http://www.ict.kth.se/~cschulte/> > > > > -----Original Message----- > From: Pascal Francq (Mailing lists) [mailto:mailing-l...@francq.info > <mailto:l...@francq.info>] > Sent: Thursday, May 23, 2013 5:43 PM > To: cschu...@kth.se <mailto:cschu...@kth.se> > Subject: Re: [gecode-users] Consecutive instances of Gecode produce > > different > > results > > I use two Gecode::IntVarArray variables I and v. The code for the > > constraints and > > the branching is the following one : > > // Maximal value <= 1 > rel(*this,1>=sum(v)); > > // Sum_(i)(2*v[i]-Sum_(j,j<>i)(I[i,j])>=0 > for(size_t i=0;i<4;i++) > { > IntVar tmp[3]; > size_t idx(0); > for(size_t j=0;j<4;j++) > { > if(i==j) > continue; > if(idx) > tmp[idx]=expr(*this,tmp[idx-1]-abs(I[i,j])); > else > tmp[idx]=expr(*this,-abs(I[i,j])); > idx++; > } > rel(*this, 0<=2*v[i]+tmp[idx-1]); > } > > // Call my own propagator > choquetPropagator(*this,Test,v,I,Cost); > > // Make the branch > branch(*this,v,INT_VAR_SIZE_MIN(),INT_VAL_MIN()); > branch(*this,I,INT_VAR_SIZE_MIN(),INT_VAL_MIN()); > > > Le 23/05/13 17:23, Christian Schulte a écrit : > > Could you tell us which constraints and which branchings you are using? > > Best > Christian > > -- > Christian Schulte, Professor of Computer Science, KTH, > www.ict.kth.se/~cschulte/ <http://www.ict.kth.se/~cschulte/> > > > -----Original Message----- > From: users-boun...@gecode.org <mailto:users-boun...@gecode.org> > [mailto:users-boun...@gecode.org] On > Behalf Of Pascal Francq (Mailing lists) > Sent: Thursday, May 23, 2013 4:59 PM > To: users@gecode.org <mailto:users@gecode.org> > Subject: [gecode-users] Consecutive instances of Gecode produce > different results > > Hi, > I have a strange problem : I have a function that runs a Gecode > instance for a particular problem. When I call the function several > times, the result of the first run sometimes differs from those of the > > other > > ones. > > I have make some runs with valgrind, but I see nothing. Has anyone an > idea where to search ? > -- > Dr. Pascal Francq > Belgium > > _______________________________________________ > Gecode users mailing list > users@gecode.org <mailto:users@gecode.org> > https://www.gecode.org/mailman/listinfo/gecode-users > > > > -- > Dr. Pascal Francq > Belgium > > > > > > -- > Dr. Pascal Francq > Belgium > > _______________________________________________ > Gecode users mailing list > users@gecode.org <mailto:users@gecode.org> > https://www.gecode.org/mailman/listinfo/gecode-users > > > -- Dr. Pascal Francq Belgium _______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
