1 /*
2 * Copyright 2003-2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.apache.commons.math.analysis;
17
18 import org.apache.commons.math.FunctionEvaluationException;
19
20 /***
21 * Auxillary class for testing solvers.
22 *
23 * The function is extraordinarily well behaved around zero roots: it
24 * has an inflection point there (second order derivative is zero),
25 * which means linear approximation (Regula Falsi) will converge
26 * quadratically.
27 *
28 * @version $Revision: 155427 $ $Date: 2005-02-26 06:11:52 -0700 (Sat, 26 Feb 2005) $
29 */
30 public class SinFunction implements DifferentiableUnivariateRealFunction {
31
32 /* Evaluate sinus fuction.
33 * @see org.apache.commons.math.UnivariateRealFunction#value(double)
34 */
35 public double value(double x) throws FunctionEvaluationException {
36 return Math.sin(x);
37 }
38
39 /* First derivative of sinus function
40 */
41 public UnivariateRealFunction derivative() {
42 return new UnivariateRealFunction() {
43 public double value(double x) throws FunctionEvaluationException {
44 return Math.cos(x);
45 }
46 };
47 }
48
49 }