001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.math4.optim.linear;
018
019/**
020 * Types of relationships between two cells in a Solver {@link LinearConstraint}.
021 *
022 * @since 2.0
023 */
024public enum Relationship {
025    /** Equality relationship. */
026    EQ("="),
027    /** Lesser than or equal relationship. */
028    LEQ("<="),
029    /** Greater than or equal relationship. */
030    GEQ(">=");
031
032    /** Display string for the relationship. */
033    private final String stringValue;
034
035    /**
036     * Simple constructor.
037     *
038     * @param stringValue Display string for the relationship.
039     */
040    Relationship(String stringValue) {
041        this.stringValue = stringValue;
042    }
043
044    /** {@inheritDoc} */
045    @Override
046    public String toString() {
047        return stringValue;
048    }
049
050    /**
051     * Gets the relationship obtained when multiplying all coefficients by -1.
052     *
053     * @return the opposite relationship.
054     */
055    public Relationship oppositeRelationship() {
056        switch (this) {
057        case LEQ :
058            return GEQ;
059        case GEQ :
060            return LEQ;
061        default :
062            return EQ;
063        }
064    }
065}