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.math.analysis;
018    
019    import org.apache.commons.math.FunctionEvaluationException;
020    
021    /**
022     * Auxillary class for testing solvers.
023     *
024     * The function is extraordinarily well behaved around zero roots: it
025     * has an inflection point there (second order derivative is zero),
026     * which means linear approximation (Regula Falsi) will converge
027     * quadratically.
028     * 
029     * @version $Revision: 799857 $ $Date: 2009-08-01 09:07:12 -0400 (Sat, 01 Aug 2009) $
030     */
031    public class SinFunction implements DifferentiableUnivariateRealFunction {
032    
033        /* Evaluate sinus fuction.
034         * @see org.apache.commons.math.UnivariateRealFunction#value(double)
035         */
036        public double value(double x) throws FunctionEvaluationException {
037            return Math.sin(x);
038        }
039    
040        /* First derivative of sinus function
041         */
042        public UnivariateRealFunction derivative() {
043            return new UnivariateRealFunction() {
044                public double value(double x) throws FunctionEvaluationException {
045                    return Math.cos(x);
046                }
047            };
048        }
049    
050    }