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.math3.analysis.function;
019    
020    import org.apache.commons.math3.analysis.FunctionUtils;
021    import org.apache.commons.math3.analysis.UnivariateFunction;
022    import org.apache.commons.math3.analysis.DifferentiableUnivariateFunction;
023    import org.apache.commons.math3.analysis.differentiation.DerivativeStructure;
024    import org.apache.commons.math3.analysis.differentiation.UnivariateDifferentiableFunction;
025    import org.apache.commons.math3.util.FastMath;
026    
027    /**
028     * Power function.
029     *
030     * @since 3.0
031     * @version $Id: Power.java 1383441 2012-09-11 14:56:39Z luc $
032     */
033    public class Power implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
034        /** Power. */
035        private final double p;
036    
037        /**
038         * @param p Power.
039         */
040        public Power(double p) {
041            this.p = p;
042        }
043    
044        /** {@inheritDoc} */
045        public double value(double x) {
046            return FastMath.pow(x, p);
047        }
048    
049        /** {@inheritDoc}
050         * @deprecated as of 3.1, replaced by {@link #value(DerivativeStructure)}
051         */
052        @Deprecated
053        public UnivariateFunction derivative() {
054            return FunctionUtils.toDifferentiableUnivariateFunction(this).derivative();
055        }
056    
057        /** {@inheritDoc}
058         * @since 3.1
059         */
060        public DerivativeStructure value(final DerivativeStructure t) {
061            return t.pow(p);
062        }
063    
064    }