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;
025import org.apache.commons.math3.util.FastMath;
026
027/**
028 * Hyperbolic arc-tangent function.
029 *
030 * @since 3.0
031 */
032public class Atanh implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
033    /** {@inheritDoc} */
034    public double value(double x) {
035        return FastMath.atanh(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.atanh();
051    }
052
053}