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 * (the "License"); you may not use this file except in compliance with
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 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.commons.math3.optim;

This interface specifies how to check if an optimization algorithm has
converged.


Deciding if convergence has been reached is a problem-dependent issue. The
user should provide a class implementing this interface to allow the
optimization algorithm to stop its search according to the problem at hand.

 For convenience, three implementations that fit simple needs are already provided: SimpleValueChecker, SimpleVectorValueChecker and SimplePointChecker. The first two consider that convergence is reached when the objective function value does not change much anymore, it does not use the point set at all. The third one considers that convergence is reached when the input point set does not change much anymore, it does not use objective function value at all. 
Type parameters:
<PAIR> – Type of the (point, objective value) pair.
See Also:
SimplePointChecker
SimpleValueChecker
SimpleVectorValueChecker
Since:
3.0/**
 * This interface specifies how to check if an optimization algorithm has
 * converged.
 * <br/>
 * Deciding if convergence has been reached is a problem-dependent issue. The
 * user should provide a class implementing this interface to allow the
 * optimization algorithm to stop its search according to the problem at hand.
 * <br/>
 * For convenience, three implementations that fit simple needs are already
 * provided: {@link SimpleValueChecker}, {@link SimpleVectorValueChecker} and
 * {@link SimplePointChecker}. The first two consider that convergence is
 * reached when the objective function value does not change much anymore, it
 * does not use the point set at all.
 * The third one considers that convergence is reached when the input point
 * set does not change much anymore, it does not use objective function value
 * at all.
 *
 * @param <PAIR> Type of the (point, objective value) pair.
 *
 * @see org.apache.commons.math3.optim.SimplePointChecker
 * @see org.apache.commons.math3.optim.SimpleValueChecker
 * @see org.apache.commons.math3.optim.SimpleVectorValueChecker
 *
 * @since 3.0
 */
public interface ConvergenceChecker<PAIR> {
    
Check if the optimization algorithm has converged.
Params:
iteration – Current iteration.
previous – Best point in the previous iteration.
current – Best point in the current iteration.
Returns:
true if the algorithm is considered to have converged./**
     * Check if the optimization algorithm has converged.
     *
     * @param iteration Current iteration.
     * @param previous Best point in the previous iteration.
     * @param current Best point in the current iteration.
     * @return {@code true} if the algorithm is considered to have converged.
     */
    boolean converged(int iteration, PAIR previous, PAIR current);
}