001/*
002 *    GeoAPI - Java interfaces for OGC/ISO standards
003 *    Copyright © 2009-2023 Open Geospatial Consortium, Inc.
004 *    http://www.geoapi.org
005 *
006 *    Licensed under the Apache License, Version 2.0 (the "License");
007 *    you may not use this file except in compliance with the License.
008 *    You may obtain a copy of the License at
009 *
010 *        http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *    Unless required by applicable law or agreed to in writing, software
013 *    distributed under the License is distributed on an "AS IS" BASIS,
014 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 *    See the License for the specific language governing permissions and
016 *    limitations under the License.
017 */
018package org.opengis.referencing.operation;
019
020import org.opengis.metadata.citation.Citation;
021import org.opengis.util.InternationalString;
022import org.opengis.annotation.Classifier;
023import org.opengis.annotation.Stereotype;
024import org.opengis.annotation.UML;
025
026import static org.opengis.annotation.Obligation.*;
027import static org.opengis.annotation.Specification.*;
028
029
030/**
031 * Specification of the coordinate operation method formula.
032 * A formula may be {@linkplain #getFormula() given textually},
033 * or may be a {@linkplain #getCitation() reference to a publication}.
034 * If the operation method is not analytic, then {@code Formula} actually gives
035 * the procedure rather than an analytic formula.
036 *
037 * <p>Formulas are given by {@link OperationMethod#getFormula()}.
038 * {@code Formula} objects are for human reading; the object that actually does the work
039 * of applying the formula or procedure to coordinate values is {@link MathTransform}.</p>
040 *
041 * @author  OGC Topic 2 (for abstract model and documentation)
042 * @author  Martin Desruisseaux (Geomatys)
043 * @version 3.1
044 * @since   2.3
045 *
046 * @see MathTransform
047 * @see OperationMethod#getFormula()
048 */
049@Classifier(Stereotype.UNION)
050@UML(identifier="Formula", specification=ISO_19111)
051public interface Formula {
052    /**
053     * Returns the formula(s) or procedure used by this operation method.
054     * At least one of {@code getFormula()} and {@link #getCitation()} shall be supplied.
055     *
056     * @return the formula used by the operation method, or {@code null} if none.
057     */
058    @UML(identifier="formula", obligation=CONDITIONAL, specification=ISO_19111)
059    InternationalString getFormula();
060
061    /**
062     * Returns a reference to a publication giving the formula(s) or procedure used by this operation method.
063     * At least one of {@link #getFormula()} and {@code getCitation()} shall be supplied.
064     *
065     * @return reference to a publication giving the formula, or {@code null} if none.
066     */
067    @UML(identifier="formulaCitation", obligation=CONDITIONAL, specification=ISO_19111)
068    Citation getCitation();
069}