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     * <code>e<sup>x</sup>-1</code> function.
029     *
030     * @since 3.0
031     * @version $Id: Expm1.java 1383441 2012-09-11 14:56:39Z luc $
032     */
033    public class Expm1 implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
034        /** {@inheritDoc} */
035        public double value(double x) {
036            return FastMath.expm1(x);
037        }
038    
039        /** {@inheritDoc}
040         * @deprecated as of 3.1, replaced by {@link #value(DerivativeStructure)}
041         */
042        @Deprecated
043        public UnivariateFunction derivative() {
044            return FunctionUtils.toDifferentiableUnivariateFunction(this).derivative();
045        }
046    
047        /** {@inheritDoc}
048         * @since 3.1
049         */
050        public DerivativeStructure value(final DerivativeStructure t) {
051            return t.expm1();
052        }
053    
054    }