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     */
017    package org.apache.commons.math3.optim.linear;
018    
019    /**
020     * Types of relationships between two cells in a Solver {@link LinearConstraint}.
021     *
022     * @version $Id: Relationship.java 1416643 2012-12-03 19:37:14Z tn $
023     * @since 2.0
024     */
025    public enum Relationship {
026        /** Equality relationship. */
027        EQ("="),
028        /** Lesser than or equal relationship. */
029        LEQ("<="),
030        /** Greater than or equal relationship. */
031        GEQ(">=");
032    
033        /** Display string for the relationship. */
034        private final String stringValue;
035    
036        /**
037         * Simple constructor.
038         *
039         * @param stringValue Display string for the relationship.
040         */
041        private Relationship(String stringValue) {
042            this.stringValue = stringValue;
043        }
044    
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    }