RMSConvergenceChecker.java

/* Copyright 2022-2026 Romain Serra
 * Licensed to CS GROUP (CS) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * CS licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.orekit.estimation.leastsquares;

import org.hipparchus.optim.ConvergenceChecker;
import org.hipparchus.optim.nonlinear.vector.leastsquares.LeastSquaresProblem;
import org.hipparchus.util.FastMath;

/**
 * Convergence checker for non-linear least squares based on weighted RMS alone.
 * @author Romain Serra
 * @since 14.0
 */
public class RMSConvergenceChecker implements ConvergenceChecker<LeastSquaresProblem.Evaluation> {

    /** Relative threshold for convergence on weighted RMS. */
    private final double threshold;

    /**
     * Constructor.
     * @param threshold relative threshold on RMS check
     */
    public RMSConvergenceChecker(final double threshold) {
        this.threshold = FastMath.abs(threshold);
    }

    /**
     * Getter for the RMS relative threshold.
     * @return threshold
     */
    public double getThreshold() {
        return threshold;
    }

    @Override
    public boolean converged(final int iteration, final LeastSquaresProblem.Evaluation previous,
                             final LeastSquaresProblem.Evaluation current) {
        return FastMath.abs(1. - current.getRMS() / previous.getRMS()) < threshold;
    }
}