mirror of https://github.com/jlizier/jidt
111 lines
4.0 KiB
Java
111 lines
4.0 KiB
Java
/*
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* Java Information Dynamics Toolkit (JIDT)
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* Copyright (C) 2017, Joseph T. Lizier
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* This class was originally distributed as part of the Apache Commons
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* Math3 library (3.6.1), under the Apache License Version 2.0, which is
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* copied below. This Apache 2 software is now included as a derivative
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* work in the GPLv3 licensed JIDT project, as per:
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* http://www.apache.org/licenses/GPL-compatibility.html
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*
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* The original Apache source code has been modified as follows:
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* -- We have modified package names to sit inside the JIDT structure.
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*/
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package infodynamics.utils.commonsmath3.analysis;
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/**
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* An interface representing a univariate real function.
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* <p>
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* When a <em>user-defined</em> function encounters an error during
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* evaluation, the {@link #value(double) value} method should throw a
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* <em>user-defined</em> unchecked exception.</p>
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* <p>
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* The following code excerpt shows the recommended way to do that using
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* a root solver as an example, but the same construct is applicable to
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* ODE integrators or optimizers.</p>
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*
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* <pre>
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* private static class LocalException extends RuntimeException {
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* // The x value that caused the problem.
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* private final double x;
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*
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* public LocalException(double x) {
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* this.x = x;
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* }
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*
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* public double getX() {
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* return x;
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* }
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* }
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*
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* private static class MyFunction implements UnivariateFunction {
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* public double value(double x) {
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* double y = hugeFormula(x);
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* if (somethingBadHappens) {
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* throw new LocalException(x);
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* }
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* return y;
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* }
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* }
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*
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* public void compute() {
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* try {
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* solver.solve(maxEval, new MyFunction(a, b, c), min, max);
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* } catch (LocalException le) {
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* // Retrieve the x value.
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* }
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* }
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* </pre>
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*
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* As shown, the exception is local to the user's code and it is guaranteed
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* that Apache Commons Math will not catch it.
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*
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*/
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public interface UnivariateFunction {
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/**
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* Compute the value of the function.
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*
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* @param x Point at which the function value should be computed.
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* @return the value of the function.
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* @throws IllegalArgumentException when the activated method itself can
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* ascertain that a precondition, specified in the API expressed at the
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* level of the activated method, has been violated.
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* When Commons Math throws an {@code IllegalArgumentException}, it is
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* usually the consequence of checking the actual parameters passed to
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* the method.
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*/
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double value(double x);
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}
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