/*
    * Copyright (C) 2020 Alberto Irurueta Carro (alberto@irurueta.com)
    *
    * Licensed 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 com.irurueta.navigation.inertial.calibration.magnetometer;
  
  import com.irurueta.algebra.Matrix;
  import com.irurueta.navigation.LockedException;
  import com.irurueta.navigation.NotReadyException;
  import com.irurueta.navigation.frames.ECEFPosition;
  import com.irurueta.navigation.frames.NEDPosition;
  import com.irurueta.navigation.inertial.calibration.CalibrationException;
  import com.irurueta.navigation.inertial.calibration.StandardDeviationBodyMagneticFluxDensity;
  import com.irurueta.navigation.inertial.wmm.WorldMagneticModel;
  import com.irurueta.numerical.robust.LMedSRobustEstimator;
  import com.irurueta.numerical.robust.LMedSRobustEstimatorListener;
  import com.irurueta.numerical.robust.RobustEstimator;
  import com.irurueta.numerical.robust.RobustEstimatorException;
  import com.irurueta.numerical.robust.RobustEstimatorMethod;
  
  import java.io.IOException;
  import java.util.List;
  
  /**
   * Robustly estimates magnetometer hard-iron biases, cross couplings and
   * scaling factors using LMedS algorithm.
   * <p>
   * To use this calibrator at least 10 measurements taken at a single known
   * position and instant must be taken at 10 different unknown orientations and
   * zero velocity when common z-axis is assumed, otherwise at least 13
   * measurements are required.
   * <p>
   * Measured magnetic flux density is assumed to follow the model shown below:
   * <pre>
   *     mBmeas = bm + (I + Mm) * mBtrue + w
   * </pre>
   * Where:
   * - mBmeas is the measured magnetic flux density. This is a 3x1 vector.
   * - bm is magnetometer hard-iron bias. Ideally, on a perfect magnetometer,
   * this should be a 3x1 zero vector.
   * - I is the 3x3 identity matrix.
   * - Mm is the 3x3 soft-iron matrix containing cross-couplings and scaling
   * factors. Ideally, on a perfect magnetometer, this should be a 3x3 zero
   * matrix.
   * - mBtrue is ground-truth magnetic flux density. This is a 3x1 vector.
   * - w is measurement noise. This is a 3x1 vector.
   * Notice that this calibrator assumes that all measurements are taken in
   * a short span of time, where Earth magnetic field can be assumed to be
   * constant at provided location and instant.
   */
  public class LMedSRobustKnownPositionAndInstantMagnetometerCalibrator extends
          RobustKnownPositionAndInstantMagnetometerCalibrator {
  
      /**
       * Default value to be used for stop threshold. Stop threshold can be used to
       * avoid keeping the algorithm unnecessarily iterating in case that best
       * estimated threshold using median of residuals is not small enough. Once a
       * solution is found that generates a threshold below this value, the
       * algorithm will stop.
       * The stop threshold can be used to prevent the LMedS algorithm iterating
       * too many times in cases where samples have a very similar accuracy.
       * For instance, in cases where proportion of outliers is very small (close
       * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
       * iterate for a long time trying to find the best solution when indeed
       * there is no need to do that if a reasonable threshold has already been
       * reached.
       * Because of this behaviour the stop threshold can be set to a value much
       * lower than the one typically used in LMedS, and yet the algorithm could
       * still produce even smaller thresholds in estimated results.
       */
      public static final double DEFAULT_STOP_THRESHOLD = 1e-9;
  
      /**
       * Minimum allowed stop threshold value.
       */
      public static final double MIN_STOP_THRESHOLD = 0.0;
  
      /**
       * Threshold to be used to keep the algorithm iterating in case that best
       * estimated threshold using median of residuals is not small enough. Once
       * a solution is found that generates a threshold below this value, the
       * algorithm will stop.
       * The stop threshold can be used to prevent the LMedS algorithm iterating
       * too many times in cases where samples have a very similar accuracy.
       * For instance, in cases where proportion of outliers is very small (close
       * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
       * iterate for a long time trying to find the best solution when indeed
       * there is no need to do that if a reasonable threshold has already been
      * reached.
      * Because of this behaviour the stop threshold can be set to a value much
      * lower than the one typically used in LMedS, and yet the algorithm could
      * still produce even smaller thresholds in estimated results.
      */
     private double stopThreshold = DEFAULT_STOP_THRESHOLD;
 
     /**
      * Constructor.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator() {
         super();
     }
 
     /**
      * Constructor.
      *
      * @param listener listener to handle events raised by this calibrator.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(listener);
     }
 
     /**
      * Constructor.
      *
      * @param measurements list of body magnetic flux density
      *                     measurements with standard deviation of
      *                     magnetometer measurements taken at the same
      *                     position with zero velocity and unknown different
      *                     orientations.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final List<StandardDeviationBodyMagneticFluxDensity> measurements) {
         super(measurements);
     }
 
     /**
      * Constructor.
      *
      * @param commonAxisUsed indicates whether z-axis is assumed to be common
      *                       for the accelerometer, gyroscope and magnetometer.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(final boolean commonAxisUsed) {
         super(commonAxisUsed);
     }
 
     /**
      * Constructor.
      *
      * @param magneticModel Earth's magnetic model. If null, a default model
      *                      will be used instead.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(final WorldMagneticModel magneticModel) {
         super(magneticModel);
     }
 
     /**
      * Constructor.
      *
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(final double[] initialHardIron) {
         super(initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(final Matrix initialHardIron) {
         super(initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final Matrix initialHardIron, final Matrix initialMm) {
         super(initialHardIron, initialMm);
     }
 
     /**
      * Constructor.
      *
      * @param position position where body magnetic flux density measurements
      *                 have been taken.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(final NEDPosition position) {
         super(position);
     }
 
     /**
      * Constructor.
      *
      * @param position     position where body magnetic flux density measurements
      *                     have been taken.
      * @param measurements collection of body magnetic flux density
      *                     measurements with standard deviation of
      *                     magnetometer measurements taken at the same
      *                     position with zero velocity and unknown different
      *                     orientations.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements) {
         super(position, measurements);
     }
 
     /**
      * Constructor.
      *
      * @param position     position where body magnetic flux density measurements
      *                     have been taken.
      * @param measurements collection of body magnetic flux density
      *                     measurements with standard deviation of
      *                     magnetometer measurements taken at the same
      *                     position with zero velocity and unknown different
      *                     orientations.
      * @param listener     listener to handle events raised by this calibrator.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position       position where body magnetic flux density measurements
      *                       have been taken.
      * @param measurements   collection of body magnetic flux density
      *                       measurements with standard deviation of
      *                       magnetometer measurements taken at the same
      *                       position with zero velocity and unknown different
      *                       orientations.
      * @param commonAxisUsed indicates whether z-axis is assumed to be common
      *                       for the accelerometer, gyroscope and magnetometer.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed) {
         super(position, measurements, commonAxisUsed);
     }
 
     /**
      * Constructor.
      *
      * @param position       position where body magnetic flux density measurements
      *                       have been taken.
      * @param measurements   collection of body magnetic flux density
      *                       measurements with standard deviation of
      *                       magnetometer measurements taken at the same
      *                       position with zero velocity and unknown different
      *                       orientations.
      * @param commonAxisUsed indicates whether z-axis is assumed to be common
      *                       for the accelerometer, gyroscope and magnetometer.
      * @param listener       listener to handle events raised by this calibrator.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final double[] initialHardIron) {
         super(position, measurements, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final double[] initialHardIron,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final double[] initialHardIron) {
         super(position, measurements, commonAxisUsed, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final double[] initialHardIron,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron) {
         super(position, measurements, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron, final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron) {
         super(position, measurements, commonAxisUsed, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron, final Matrix initialMm) {
         super(position, measurements, initialHardIron, initialMm);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron, final Matrix initialMm,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, initialHardIron, initialMm, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron, final Matrix initialMm) {
         super(position, measurements, commonAxisUsed, initialHardIron, initialMm);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final NEDPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron, final Matrix initialMm,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, initialHardIron, initialMm, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position position where body magnetic flux density measurements
      *                 have been taken.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(final ECEFPosition position) {
         super(position);
     }
 
     /**
      * Constructor.
      *
      * @param position     position where body magnetic flux density measurements
      *                     have been taken.
      * @param measurements collection of body magnetic flux density
      *                     measurements with standard deviation of
      *                     magnetometer measurements taken at the same
      *                     position with zero velocity and unknown different
      *                     orientations.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements) {
         super(position, measurements);
     }
 
     /**
      * Constructor.
      *
      * @param position     position where body magnetic flux density measurements
      *                     have been taken.
      * @param measurements collection of body magnetic flux density
      *                     measurements with standard deviation of
      *                     magnetometer measurements taken at the same
      *                     position with zero velocity and unknown different
      *                     orientations.
      * @param listener     listener to handle events raised by this calibrator.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position       position where body magnetic flux density measurements
      *                       have been taken.
      * @param measurements   collection of body magnetic flux density
      *                       measurements with standard deviation of
      *                       magnetometer measurements taken at the same
      *                       position with zero velocity and unknown different
      *                       orientations.
      * @param commonAxisUsed indicates whether z-axis is assumed to be common
      *                       for the accelerometer, gyroscope and magnetometer.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed) {
         super(position, measurements, commonAxisUsed);
     }
 
     /**
      * Constructor.
      *
      * @param position       position where body magnetic flux density measurements
      *                       have been taken.
      * @param measurements   collection of body magnetic flux density
      *                       measurements with standard deviation of
      *                       magnetometer measurements taken at the same
      *                       position with zero velocity and unknown different
      *                       orientations.
      * @param commonAxisUsed indicates whether z-axis is assumed to be common
      *                       for the accelerometer, gyroscope and magnetometer.
      * @param listener       listener to handle events raised by this calibrator.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final double[] initialHardIron) {
         super(position, measurements, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final double[] initialHardIron,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final double[] initialHardIron) {
         super(position, measurements, commonAxisUsed, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron array does
      *                                  not have length 3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final double[] initialHardIron,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron) {
         super(position, measurements, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron, final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron) {
         super(position, measurements, commonAxisUsed, initialHardIron);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, initialHardIron, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron, final Matrix initialMm) {
         super(position, measurements, initialHardIron, initialMm);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final Matrix initialHardIron, final Matrix initialMm,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, initialHardIron, initialMm, listener);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron, final Matrix initialMm) {
         super(position, measurements, commonAxisUsed, initialHardIron, initialMm);
     }
 
     /**
      * Constructor.
      *
      * @param position        position where body magnetic flux density measurements
      *                        have been taken.
      * @param measurements    collection of body magnetic flux density
      *                        measurements with standard deviation of
      *                        magnetometer measurements taken at the same
      *                        position with zero velocity and unknown different
      *                        orientations.
      * @param commonAxisUsed  indicates whether z-axis is assumed to be common
      *                        for the accelerometer, gyroscope and magnetometer.
      * @param initialHardIron initial hard-iron to find a solution.
      * @param initialMm       initial soft-iron matrix containing scale factors
      *                        and cross coupling errors.
      * @param listener        listener to handle events raised by this calibrator.
      * @throws IllegalArgumentException if provided hard-iron matrix is not
      *                                  3x1 or if soft-iron matrix is not
      *                                  3x3.
      */
     public LMedSRobustKnownPositionAndInstantMagnetometerCalibrator(
             final ECEFPosition position, final List<StandardDeviationBodyMagneticFluxDensity> measurements,
             final boolean commonAxisUsed, final Matrix initialHardIron, final Matrix initialMm,
             final RobustKnownPositionAndInstantMagnetometerCalibratorListener listener) {
         super(position, measurements, commonAxisUsed, initialHardIron, initialMm, listener);
     }
 
     /**
      * Returns threshold to be used to keep the algorithm iterating in case that
      * best estimated threshold using median of residuals is not small enough.
      * Once a solution is found that generates a threshold below this value, the
      * algorithm will stop.
      * The stop threshold can be used to prevent the LMedS algorithm to iterate
      * too many times in cases where samples have a very similar accuracy.
      * For instance, in cases where proportion of outliers is very small (close
      * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
      * iterate for a long time trying to find the best solution when indeed
      * there is no need to do that if a reasonable threshold has already been
      * reached.
      * Because of this behaviour the stop threshold can be set to a value much
      * lower than the one typically used in RANSAC, and yet the algorithm could
      * still produce even smaller thresholds in estimated results.
      *
      * @return stop threshold to stop the algorithm prematurely when a certain
      * accuracy has been reached.
      */
     public double getStopThreshold() {
         return stopThreshold;
     }
 
     /**
      * Sets threshold to be used to keep the algorithm iterating in case that
      * best estimated threshold using median of residuals is not small enough.
      * Once a solution is found that generates a threshold below this value,
      * the algorithm will stop.
      * The stop threshold can be used to prevent the LMedS algorithm to iterate
      * too many times in cases where samples have a very similar accuracy.
      * For instance, in cases where proportion of outliers is very small (close
      * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
      * iterate for a long time trying to find the best solution when indeed
      * there is no need to do that if a reasonable threshold has already been
      * reached.
      * Because of this behaviour the stop threshold can be set to a value much
      * lower than the one typically used in RANSAC, and yet the algorithm could
      * still produce even smaller thresholds in estimated results.
      *
      * @param stopThreshold stop threshold to stop the algorithm prematurely
      *                      when a certain accuracy has been reached.
      * @throws IllegalArgumentException if provided value is zero or negative.
      * @throws LockedException          if calibrator is currently running.
      */
     public void setStopThreshold(final double stopThreshold) throws LockedException {
         if (running) {
             throw new LockedException();
         }
         if (stopThreshold <= MIN_STOP_THRESHOLD) {
             throw new IllegalArgumentException();
         }
 
         this.stopThreshold = stopThreshold;
     }
 
     /**
      * Estimates magnetometer calibration parameters containing hard-iron
      * bias and soft-iron scale factors and cross-coupling errors.
      *
      * @throws LockedException      if calibrator is currently running.
      * @throws NotReadyException    if calibrator is not ready.
      * @throws CalibrationException if estimation fails for numerical reasons.
      */
     @SuppressWarnings("DuplicatedCode")
     @Override
     public void calibrate() throws LockedException, NotReadyException, CalibrationException {
         if (running) {
             throw new LockedException();
         }
         if (!isReady()) {
             throw new NotReadyException();
         }
 
         final var innerEstimator = new LMedSRobustEstimator<>(new LMedSRobustEstimatorListener<PreliminaryResult>() {
             @Override
             public int getTotalSamples() {
                 return measurements.size();
             }
 
             @Override
             public int getSubsetSize() {
                 return preliminarySubsetSize;
             }
 
             @Override
             public void estimatePreliminarSolutions(
                     final int[] samplesIndices, final List<PreliminaryResult> solutions) {
                 computePreliminarySolutions(samplesIndices, solutions);
             }
 
             @Override
             public double computeResidual(final PreliminaryResult currentEstimation, final int i) {
                 return computeError(measurements.get(i), currentEstimation);
             }
 
             @Override
             public boolean isReady() {
                 return LMedSRobustKnownPositionAndInstantMagnetometerCalibrator.this.isReady();
             }
 
             @Override
             public void onEstimateStart(final RobustEstimator<PreliminaryResult> estimator) {
                 // no action needed
             }
 
             @Override
             public void onEstimateEnd(final RobustEstimator<PreliminaryResult> estimator) {
                 // no action needed
             }
 
             @Override
             public void onEstimateNextIteration(
                     final RobustEstimator<PreliminaryResult> estimator, final int iteration) {
                 if (listener != null) {
                     listener.onCalibrateNextIteration(
                             LMedSRobustKnownPositionAndInstantMagnetometerCalibrator.this, iteration);
                 }
             }
 
             @Override
             public void onEstimateProgressChange(
                     final RobustEstimator<PreliminaryResult> estimator, final float progress) {
                 if (listener != null) {
                     listener.onCalibrateProgressChange(
                             LMedSRobustKnownPositionAndInstantMagnetometerCalibrator.this, progress);
                 }
             }
         });
 
         try {
             running = true;
 
             if (listener != null) {
                 listener.onCalibrateStart(this);
             }
 
             inliersData = null;
 
             initialize();
 
             innerEstimator.setConfidence(confidence);
             innerEstimator.setMaxIterations(maxIterations);
             innerEstimator.setProgressDelta(progressDelta);
             innerEstimator.setStopThreshold(stopThreshold);
             final var preliminaryResult = innerEstimator.estimate();
             inliersData = innerEstimator.getInliersData();
 
             attemptRefine(preliminaryResult);
 
             if (listener != null) {
                 listener.onCalibrateEnd(this);
             }
 
         } catch (final com.irurueta.numerical.LockedException e) {
             throw new LockedException(e);
         } catch (final com.irurueta.numerical.NotReadyException e) {
             throw new NotReadyException(e);
         } catch (final RobustEstimatorException | IOException e) {
             throw new CalibrationException(e);
         } finally {
             running = false;
         }
 
     }
 
     /**
      * Returns method being used for robust estimation.
      *
      * @return method being used for robust estimation.
      */
     @Override
     public RobustEstimatorMethod getMethod() {
         return RobustEstimatorMethod.LMEDS;
     }
 
     /**
      * Indicates whether this calibrator requires quality scores for each
      * measurement or not.
      *
      * @return true if quality scores are required, false otherwise.
      */
     @Override
     public boolean isQualityScoresRequired() {
         return false;
     }
 }