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.DifferentiableUnivariateFunction;
021import org.apache.commons.math3.analysis.differentiation.DerivativeStructure;
022import org.apache.commons.math3.analysis.differentiation.UnivariateDifferentiableFunction;
023
024/**
025 * Constant function.
026 *
027 * @since 3.0
028 */
029public class Constant implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
030    /** Constant. */
031    private final double c;
032
033    /**
034     * @param c Constant.
035     */
036    public Constant(double c) {
037        this.c = c;
038    }
039
040    /** {@inheritDoc} */
041    public double value(double x) {
042        return c;
043    }
044
045    /** {@inheritDoc}
046     * @deprecated as of 3.1, replaced by {@link #value(DerivativeStructure)}
047     */
048    @Deprecated
049    public DifferentiableUnivariateFunction derivative() {
050        return new Constant(0);
051    }
052
053    /** {@inheritDoc}
054     * @since 3.1
055     */
056    public DerivativeStructure value(final DerivativeStructure t) {
057        return new DerivativeStructure(t.getFreeParameters(), t.getOrder(), c);
058    }
059
060}