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    
018    package org.apache.commons.math.optimization.linear;
019    
020    /**
021     * Types of relationships between two cells in a Solver {@link LinearConstraint}.
022     * @version $Revision: 758920 $ $Date: 2009-03-26 19:25:30 -0400 (Thu, 26 Mar 2009) $
023     * @since 2.0
024     */
025    public enum Relationship {
026    
027        /** Equality relationship. */
028        EQ("="),
029    
030        /** Lesser than or equal relationship. */
031        LEQ("<="),
032    
033        /** Greater than or equal relationship. */
034        GEQ(">=");
035    
036        /** Display string for the relationship. */
037        private String stringValue;
038    
039        /** Simple constructor.
040         * @param stringValue display string for the relationship
041         */
042        private Relationship(String stringValue) {
043            this.stringValue = stringValue;
044        }
045    
046        /** {@inheritDoc} */
047        @Override
048        public String toString() {
049            return stringValue;
050        }
051    
052        /**
053         * Get the relationship obtained when multiplying all coefficients by -1.
054         * @return relationship obtained when multiplying all coefficients by -1
055         */
056        public Relationship oppositeRelationship() {
057            switch (this) {
058            case LEQ :
059                return GEQ;
060            case GEQ :
061                return LEQ;
062            default :
063                return EQ;
064            }
065        }
066    
067    }