/**
* Copyright (c) 1999-2014, Ecole des Mines de Nantes
* All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the Ecole des Mines de Nantes nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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package solver.constraints.real;
import solver.constraints.Constraint;
import solver.constraints.Propagator;
import solver.exception.ContradictionException;
import solver.variables.IntVar;
import solver.variables.RealVar;
import solver.variables.Variable;
import util.ESat;
import util.tools.ArrayUtils;
/**
* Channeling constraint between integers and reals, to avoid views
*
* @author Jean-Guillaume Fages
* @since 07/04/2014
*/
public class IntEqRealConstraint extends Constraint {
//***********************************************************************************
// CONSTRUCTORS
//***********************************************************************************
/**
* Channeling between integer variables intVars and real variables realVars.
* Thus, for any i in [0,intVars.length-1], |intVars[i]-realVars[i]|< epsilon.
* intVars.length must be equal to realVars.length.
*
* @param intVars integer variables
* @param realVars real variables
* @param epsilon precision parameter
*/
public IntEqRealConstraint(final IntVar[] intVars, final RealVar[] realVars, final double epsilon) {
super("IntEqReal", new Propagator<Variable>(ArrayUtils.append(intVars,realVars)) {
int n = intVars.length;
@Override
public void propagate(int evtmask) throws ContradictionException {
assert n==realVars.length;
for(int i=0;i<n;i++) {
IntVar intVar = intVars[i];
RealVar realVar = realVars[i];
realVar.updateBounds((double) intVar.getLB() - epsilon, (double) intVar.getUB() + epsilon, aCause);
intVar.updateLowerBound((int) Math.ceil(realVar.getLB() - epsilon), aCause);
intVar.updateUpperBound((int) Math.floor(realVar.getUB() + epsilon), aCause);
if (intVar.hasEnumeratedDomain()) {
realVar.updateBounds((double) intVar.getLB() - epsilon, (double) intVar.getUB() + epsilon, aCause);
}
}
}
@Override
public ESat isEntailed() {
assert intVars.length==realVars.length;
boolean allInst = true;
for(int i=0;i<n;i++) {
IntVar intVar = intVars[i];
RealVar realVar = realVars[i];
if ((realVar.getLB() < (double) intVar.getLB() - epsilon) || (realVar.getUB() > (double) intVar.getUB() + epsilon)) {
return ESat.FALSE;
}
if (!(intVar.isInstantiated() && realVar.isInstantiated())) {
allInst = false;
}
}
return allInst?ESat.TRUE:ESat.UNDEFINED;
}
});
}
/**
* Channeling between an integer variable intVar and a real variable realVar.
* Thus, |intVar-realVar|< epsilon.
*
* @param intVar integer variable
* @param realVar real variable
* @param epsilon precision parameter
*/
public IntEqRealConstraint(final IntVar intVar, final RealVar realVar, final double epsilon) {
this(new IntVar[]{intVar},new RealVar[]{realVar},epsilon);
}
}