Tag: Linear algebra

Hi all–I’m trying to create a custom constraint in ILOG following the extensions manual but it doesn’t seem to work. Specifically, as soon as I call *addVar* to link a variable to the constraint, the solver will terminate immediately. It doesn’t matter what the constraint actually does–the execute function can be empty and the result will be the same.

Anyone else encounter this? The following code demonstrates the issue and is mostly copied verbatim from the extensions manual (LEConstraint).

import ilog.cp.*;
import ilog.concert.*;

public class Runner {
public static void main(String[] args) {
try {
IloCP cp = new IloCP();

IloIntVar a = cp.intVar(2, 10);
IloIntVar y = cp.intVar(2, 10);
cp.add(new LEConstraint(cp, a, y));
cp.add(cp.minimize(a));
cp.solve();
} catch (IloException e) {
}
}
}

class LEConstraint extends IloCustomConstraint {
private IloIntVar _x;
private IloIntVar _y;

public LEConstraint(IloCP cp, IloIntVar x, IloIntVar y) throws IloException {
super(cp);
_x = x;
_y = y;
addVar(x);
addVar(y);
}

public void execute() {
if (isFixed(_x) && isFixed(_y))
if (getValue(_x) > getValue(_y))
setValue(_x, getValue(_x)+1);
}
}

Resulting in:

! Search terminated , no solution found.
! Number of branches : 0
! Number of fails : 0
! Total memory usage : 2.3 MB (2.3 MB CP Optimizer + 0.0 MB Concert)
! Time spent in solve : 0.01s (0.01s engine + 0.00s extraction)
! Search speed (br. / s) : 0

@Xavier Nodet