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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.interpolation;
17  
18  import com.irurueta.numerical.polynomials.Polynomial;
19  
20  /**
21   * Base class for interpolating polynomial estimators.
22   */
23  public abstract class InterpolatingPolynomialEstimator {
24      /**
25       * Estimates polynomial from provided x and y points.
26       *
27       * @param x x points the estimated polynomial passes through.
28       * @param y y points the estimated polynomial passes through.
29       * @return estimated polynomial.
30       * @throws IllegalArgumentException if any of the provided values doesn't have the same length.
31       * @throws InterpolationException   if interpolation fails for numerical reasons.
32       */
33      public Polynomial estimate(final double[] x, final double[] y) throws InterpolationException {
34          final var polynomial = new Polynomial(x.length);
35          estimate(x, y, polynomial);
36          return polynomial;
37      }
38  
39      /**
40       * Estimates polynomial coefficients from provided x and y points.
41       *
42       * @param x x points the estimated polynomial passes through.
43       * @param y y points the estimated polynomial passes through.
44       * @return coefficients of estimated polynomial.
45       * @throws IllegalArgumentException if any of the provided values doesn't have the same length.
46       * @throws InterpolationException   if interpolation fails for numerical reasons.
47       */
48      public double[] estimateCoefficients(final double[] x, final double[] y) throws InterpolationException {
49          final var result = new double[x.length];
50          estimate(x, y, result);
51          return result;
52      }
53  
54      /**
55       * Estimates polynomial from provided x and y points.
56       *
57       * @param x      x points the estimated polynomial passes through.
58       * @param y      y points the estimated polynomial passes through.
59       * @param result instance where estimated polynomial will be stored.
60       * @throws IllegalArgumentException if any of the provided values doesn't have the same length
61       *                                  or polynomial doesn't have expected order.
62       * @throws InterpolationException   if interpolation fails for numerical reasons.
63       */
64      public void estimate(final double[] x, final double[] y, final Polynomial result) throws InterpolationException {
65          estimate(x, y, result.getPolyParams());
66      }
67  
68      /**
69       * Estimates polynomial coefficients from provided x and y points.
70       *
71       * @param x   x points the estimated polynomial passes through.
72       * @param y   y points the estimated polynomial passes through.
73       * @param cof instance where coefficients of estimated polynomial will be stored.
74       * @throws IllegalArgumentException if any of the provided values doesn't have the same length.
75       * @throws InterpolationException   if interpolation fails for numerical reasons.
76       */
77      public abstract void estimate(final double[] x, final double[] y, final double[] cof)
78              throws InterpolationException;
79  }