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.algebra.Matrix;
19 import com.irurueta.algebra.WrongSizeException;
20 import com.irurueta.numerical.EvaluationException;
21
22 /**
23 * This is an exact replacement for MidPointQuadrature i.e., returns the nth stage of refinement of
24 * the integral of a function from "a" to "b", except that the function is evaluated at evenly spaced
25 * points in 1=x rather than in "x". This allows the upper limit "b" to be as large and positive as the
26 * computer allows, or the lower limit "a" to be as large and negative, but not both. "a" and "b" must
27 * have the same sign.
28 */
29 public class InfinityMidPointMatrixQuadrature extends MidPointMatrixQuadrature {
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 matrix function at required points.
37 * @throws WrongSizeException if size notified by provided listener is invalid.
38 */
39 public InfinityMidPointMatrixQuadrature(
40 final double a, final double b, final MatrixSingleDimensionFunctionEvaluatorListener listener)
41 throws WrongSizeException {
42 super(1.0 / b, 1.0 / a, listener);
43 }
44
45 /**
46 * Gets type of quadrature.
47 *
48 * @return type of quadrature.
49 */
50 @Override
51 public QuadratureType getType() {
52 return QuadratureType.INFINITY_MID_POINT;
53 }
54
55 /**
56 * Evaluates function at 1/x.
57 *
58 * @param x point where function is evaluated.
59 * @param result instance where result of evaluation is stored.
60 * @throws EvaluationException if evaluation fails.
61 */
62 @Override
63 protected void func(final double x, final Matrix result) throws EvaluationException {
64 listener.evaluate(1.0 / x, result);
65 result.multiplyByScalar(1.0 / (x * x));
66 }
67 }