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
018package org.apache.commons.math3.analysis.function;
019
020import org.apache.commons.math3.analysis.FunctionUtils;
021import org.apache.commons.math3.analysis.UnivariateFunction;
022import org.apache.commons.math3.analysis.DifferentiableUnivariateFunction;
023import org.apache.commons.math3.analysis.differentiation.DerivativeStructure;
024import org.apache.commons.math3.analysis.differentiation.UnivariateDifferentiableFunction;
025
026/**
027 * Inverse function.
028 *
029 * @since 3.0
030 */
031public class Inverse implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
032    /** {@inheritDoc} */
033    public double value(double x) {
034        return 1 / x;
035    }
036
037    /** {@inheritDoc}
038     * @deprecated as of 3.1, replaced by {@link #value(DerivativeStructure)}
039     */
040    @Deprecated
041    public UnivariateFunction derivative() {
042        return FunctionUtils.toDifferentiableUnivariateFunction(this).derivative();
043    }
044
045    /** {@inheritDoc}
046     * @since 3.1
047     */
048    public DerivativeStructure value(final DerivativeStructure t) {
049        return t.reciprocal();
050    }
051
052}