1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements.  See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License.  You may obtain a copy of the License at
8  *
9  *      http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 package org.apache.commons.math3.analysis.function;
19 
20 import org.apache.commons.math3.analysis.DifferentiableUnivariateFunction;
21 import org.apache.commons.math3.analysis.differentiation.DerivativeStructure;
22 import org.apache.commons.math3.analysis.differentiation.UnivariateDifferentiableFunction;
23 
24 /**
25  * Constant function.
26  *
27  * @since 3.0
28  */
29 public class Constant implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction {
30     /** Constant. */
31     private final double c;
32 
33     /**
34      * @param c Constant.
35      */
Constant(double c)36     public Constant(double c) {
37         this.c = c;
38     }
39 
40     /** {@inheritDoc} */
value(double x)41     public double value(double x) {
42         return c;
43     }
44 
45     /** {@inheritDoc}
46      * @deprecated as of 3.1, replaced by {@link #value(DerivativeStructure)}
47      */
48     @Deprecated
derivative()49     public DifferentiableUnivariateFunction derivative() {
50         return new Constant(0);
51     }
52 
53     /** {@inheritDoc}
54      * @since 3.1
55      */
value(final DerivativeStructure t)56     public DerivativeStructure value(final DerivativeStructure t) {
57         return new DerivativeStructure(t.getFreeParameters(), t.getOrder(), c);
58     }
59 
60 }
61