1 /*
2 * Copyright (C) 2023 Alberto Irurueta Carro (alberto@irurueta.com)
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 com.irurueta.numerical.integration;
17
18 import com.irurueta.numerical.EvaluationException;
19 import com.irurueta.numerical.SingleDimensionFunctionEvaluatorListener;
20 /**
21 * This is an exact replacement for MidPointQuadrature, except that it allows for an inverse
22 * square-root singularity in the integrand at the upper limit b.
23 */
24 public class UpperSquareRootMidPointQuadrature extends MidPointQuadrature {
25
26 /**
27 * Original upper bound of integration.
28 */
29 private final double borig;
30
31 /**
32 * Constructor.
33 *
34 * @param a Lower limit of integration.
35 * @param b Upper limit of integration.
36 * @param listener listener to evaluate a single dimension function at required points.
37 */
38 public UpperSquareRootMidPointQuadrature(
39 final double a, final double b, final SingleDimensionFunctionEvaluatorListener listener) {
40 super(0.0, Math.sqrt(b - a), listener);
41 borig = b;
42 }
43
44 /**
45 * Gets type of quadrature.
46 *
47 * @return type of quadrature.
48 */
49 @Override
50 public QuadratureType getType() {
51 return QuadratureType.UPPER_SQUARE_ROOT_MID_POINT;
52 }
53
54 /**
55 * Evaluates function at 2*x*f(a0+x^2).
56 *
57 * @param x point where function is evaluated.
58 * @return result of evaluation.
59 * @throws EvaluationException if evaluation fails.
60 */
61 @Override
62 protected double func(final double x) throws EvaluationException {
63 return 2.0 * x * listener.evaluate(borig - x * x);
64 }
65 }