AbstractAmbiguityModifier.java

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package org.orekit.estimation.measurements.modifiers;

import java.util.Collections;
import java.util.List;

import org.hipparchus.util.FastMath;
import org.orekit.estimation.measurements.EstimatedMeasurement;
import org.orekit.estimation.measurements.EstimatedMeasurementBase;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.TimeSpanMap.Span;

/**
 * Base class for phase ambiguity modifier.
 * @author Bryan Cazabonne
 * @author Luc Maisonobe
 * @since 10.3
 */
public class AbstractAmbiguityModifier {

    /** Ambiguity scale factor.
     * <p>
     * We use a power of 2 to avoid numeric noise introduction
     * in the multiplications/divisions sequences.
     * </p>
     */
    private static final double AMBIGUITY_SCALE = FastMath.scalb(1.0, 26);

    /** Ambiguity parameter. */
    private final ParameterDriver ambiguity;

    /** Constructor.
     * @param key key to identify the ambiguity
     * @param ambiguity initial value of ambiguity
     */
    public AbstractAmbiguityModifier(final int key, final double ambiguity) {
        this.ambiguity = new ParameterDriver("ambiguity-" + key, ambiguity, AMBIGUITY_SCALE,
                                             Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY);
    }

    /** Get the drivers for this modifier.
     * @return drivers for this modifier
     */
    protected List<ParameterDriver> getDrivers() {
        return Collections.singletonList(ambiguity);
    }

    /** Modify measurement.
     * @param estimated measurement to modify
     */
    protected void doModifyWithoutDerivatives(final EstimatedMeasurementBase<?> estimated) {
        // Apply the ambiguity to the measurement value
        for (Span<String> span = ambiguity.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
            final double[] value = estimated.getEstimatedValue();
            value[0] += ambiguity.getValue(span.getStart());
            estimated.setEstimatedValue(value);
        }
    }

    /** Modify measurement.
     * @param estimated measurement to modify
     */
    protected void doModify(final EstimatedMeasurement<?> estimated) {

        // apply the ambiguity to the measurement derivatives
        for (Span<String> span = ambiguity.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
            if (ambiguity.isSelected()) {
            // add the partial derivatives
                estimated.setParameterDerivatives(ambiguity, span.getStart(), 1.0);
            }
        }

        // apply the ambiguity to the measurement value
        doModifyWithoutDerivatives(estimated);

    }

}