    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
    026    /**
    027     * Inverse function.
    028     *
    029     * @since 3.0
    030     * @version $Id: Inverse.java 1383441 2012-09-11 14:56:39Z luc $
    031     */
    032    public class Inverse implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
    033        /** {@inheritDoc} */
    034        public double value(double x) {
    035            return 1 / x;
    036        }
    037
    038        /** {@inheritDoc}
    039         * @deprecated as of 3.1, replaced by {@link #value(DerivativeStructure)}
    040         */
    041        @Deprecated
    042        public UnivariateFunction derivative() {
    043            return FunctionUtils.toDifferentiableUnivariateFunction(this).derivative();
    044        }
    045
    046        /** {@inheritDoc}
    047         * @since 3.1
    048         */
    049        public DerivativeStructure value(final DerivativeStructure t) {
    050            return t.reciprocal();
    051        }
    052
    053    }