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 * Arc-tangent function.
029 *
030 * @since 3.0
031 * @version $Id: Atan.java 1383441 2012-09-11 14:56:39Z luc $
032 */
033public class Atan implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
034    /** {@inheritDoc} */
035    public double value(double x) {
036        return FastMath.atan(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.atan();
052    }
053
054}