org.chocosolver.solver.search.restart.InnerOuterCutoff Maven / Gradle / Ivy
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2025, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.search.restart;
/**
* An inner/outer cutoff strategy.
*
* At step n, the next cutoff is computed with the following function : s*g^n
* If the inner cutoff is greater than the outer cutoff, the outer cutoff is multiplied by the outer factor.
* Otherwise, the inner cutoff is multiplied by the geometrical factor.
* @author Charles Prud'homme
* @since 11/10/2024
*/
public final class InnerOuterCutoff extends GeometricalCutoff {
private final double outerFactor;
private double outerFactorPower;
/**
* A geometrical cutoff strategy.
* At step n, the next cutoff is computed with the following function : s*g^n
*
* @param s scale factor
* @param gi geometrical factor
* @param go outer factor
* @throws IllegalArgumentException if g is not strictly greater than 1
*/
@SuppressWarnings("WeakerAccess")
public InnerOuterCutoff(long s, double gi, double go) throws IllegalArgumentException {
super(s, gi);
this.outerFactor = go;
this.outerFactorPower = 1;
}
/**
* @return at call n, the next cutoff is computed with the following function :
* s*g^n
*/
@Override
public long getNextCutoff() {
final long inner = (long) Math.floor(scaleFactor * geometricalFactorPower) * grower.getAsInt();
final long outer = (long) Math.floor(scaleFactor * outerFactorPower) * grower.getAsInt();
if (inner >= outer) {
outerFactorPower *= outerFactor;
geometricalFactorPower = 1.;
} else {
geometricalFactorPower *= geometricalFactor;
}
return inner;
}
@Override
public void reset() {
super.reset();
this.outerFactorPower = 1;
}
@Override
public String toString() {
return "INNEROUTER(s=" + scaleFactor + ", g=" + geometricalFactor + ')';
}
}