1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 /*
19 * This is not the original file distributed by the Apache Software Foundation
20 * It has been modified by the Hipparchus project
21 */
22 package org.hipparchus.analysis;
23
24 import org.hipparchus.CalculusFieldElement;
25
26 /**
27 * An interface representing a univariate real function.
28 * <p>
29 * When a <em>user-defined</em> function encounters an error during
30 * evaluation, the {@link #value(CalculusFieldElement) value} method should throw a
31 * <em>user-defined</em> unchecked exception.</p>
32 * <p>
33 * The following code excerpt shows the recommended way to do that using
34 * a root solver as an example, but the same construct is applicable to
35 * ODE integrators or optimizers.
36 *
37 * <pre>
38 * private static class LocalException extends RuntimeException {
39 * // The x value that caused the problem.
40 * private final SomeFieldType x;
41 *
42 * public LocalException(SomeFieldType x) {
43 * this.x = x;
44 * }
45 *
46 * public double getX() {
47 * return x;
48 * }
49 * }
50 *
51 * private static class MyFunction implements FieldUnivariateFunction<SomeFieldType> {
52 * public SomeFieldType value(SomeFieldType x) {
53 * SomeFieldType y = hugeFormula(x);
54 * if (somethingBadHappens) {
55 * throw new LocalException(x);
56 * }
57 * return y;
58 * }
59 * }
60 *
61 * public void compute() {
62 * try {
63 * solver.solve(maxEval, new MyFunction(a, b, c), min, max);
64 * } catch (LocalException le) {
65 * // Retrieve the x value.
66 * }
67 * }
68 * </pre>
69 *<p>
70 * As shown, the exception is local to the user's code and it is guaranteed
71 * that Hipparchus will not catch it.</p>
72 *
73 * @param <T> the type of the field elements
74 * @see UnivariateFunction
75 * @see FieldUnivariateFunction
76 */
77 public interface CalculusFieldUnivariateFunction<T extends CalculusFieldElement<T>> {
78 /**
79 * Compute the value of the function.
80 *
81 * @param x Point at which the function value should be computed.
82 * @return the value of the function.
83 * @throws IllegalArgumentException when the activated method itself can
84 * ascertain that a precondition, specified in the API expressed at the
85 * level of the activated method, has been violated.
86 * When Hipparchus throws an {@code IllegalArgumentException}, it is
87 * usually the consequence of checking the actual parameters passed to
88 * the method.
89 */
90 T value(T x);
91 }