01: /*
02: * Copyright 2003-2004 The Apache Software Foundation.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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
31: DifferentiableUnivariateRealFunction {
32:
33: /* Evaluate sinus fuction.
34: * @see org.apache.commons.math.UnivariateRealFunction#value(double)
35: */
36: public double value(double x) throws FunctionEvaluationException {
37: return Math.sin(x);
38: }
39:
40: /* First derivative of sinus function
41: */
42: public UnivariateRealFunction derivative() {
43: return new UnivariateRealFunction() {
44: public double value(double x)
45: throws FunctionEvaluationException {
46: return Math.cos(x);
47: }
48: };
49: }
50:
51: }
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