Moreover, if the variables are 0/1 it is better to use BoolVar instead of IntVar.
Christian -- Christian Schulte, www.ict.kth.se/~cschulte/ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Guido Tack Sent: Wednesday, May 14, 2008 8:39 AM To: Javier Núñez Cc: [EMAIL PROTECTED] Subject: Re: [gecode-users] flow constraint Javier Núñez wrote: > I need make this flow constraint for a routing problem: > (in latex): \sum_j x_{ ij } = \sum_j x_{ ji } > (in ampl): sum {j in J} x[i,j] - sum {j in J} x[j,i] = 0 > > (where x[i,j] is a binary variable, for all i in I and j in J.). I > tried to do this constraint in gecodej (in java), but is incorrect: > > [...] > x = new VarMatrix<IntVar>(this, n, n, IntVar.class, 0, 1); > for (int i=0; i<n; i++) { > linear(this, x.row(i) - x.col(i) , IRT_EQ, 0); > } > [...] > > Error: "operator: cannot be applied to VarArray<IntVar>, > VarArray<IntVar>" You cannot use expressions like x-y for posting constraints (not in Java, anyway). You have to use an integer array with coefficients {1,-1} and an array of IntVar containing x.row[i] and x.col[i] instead and give those to linear. See the documentation of the linear constraint posting function. Guido _______________________________________________ Gecode users mailing list [EMAIL PROTECTED] https://www.gecode.org/mailman/listinfo/gecode-users _______________________________________________ Gecode users mailing list [EMAIL PROTECTED] https://www.gecode.org/mailman/listinfo/gecode-users
