| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.math4.legacy.analysis; |
| |
| import org.apache.commons.math4.legacy.core.RealFieldElement; |
| |
| /** |
| * An interface representing a univariate real function. |
| * <p> |
| * When a <em>user-defined</em> function encounters an error during |
| * evaluation, the {@link #value(RealFieldElement) value} method should throw a |
| * <em>user-defined</em> unchecked exception.</p> |
| * <p> |
| * The following code excerpt shows the recommended way to do that using |
| * a root solver as an example, but the same construct is applicable to |
| * ODE integrators or optimizers. |
| * |
| * <pre> |
| * private static class LocalException extends RuntimeException { |
| * // The x value that caused the problem. |
| * private final SomeFieldType x; |
| * |
| * public LocalException(SomeFieldType x) { |
| * this.x = x; |
| * } |
| * |
| * public double getX() { |
| * return x; |
| * } |
| * } |
| * |
| * private static class MyFunction implements FieldUnivariateFunction<SomeFieldType> { |
| * public SomeFieldType value(SomeFieldType x) { |
| * SomeFieldType y = hugeFormula(x); |
| * if (somethingBadHappens) { |
| * throw new LocalException(x); |
| * } |
| * return y; |
| * } |
| * } |
| * |
| * public void compute() { |
| * try { |
| * solver.solve(maxEval, new MyFunction(a, b, c), min, max); |
| * } catch (LocalException le) { |
| * // Retrieve the x value. |
| * } |
| * } |
| * </pre> |
| *<p> |
| * As shown, the exception is local to the user's code and it is guaranteed |
| * that Apache Commons Math will not catch it.</p> |
| * |
| * @param <T> the type of the field elements |
| * @since 3.6 |
| * @see UnivariateFunction |
| */ |
| public interface RealFieldUnivariateFunction<T extends RealFieldElement<T>> { |
| /** |
| * Compute the value of the function. |
| * |
| * @param x Point at which the function value should be computed. |
| * @return the value of the function. |
| * @throws IllegalArgumentException when the activated method itself can |
| * ascertain that a precondition, specified in the API expressed at the |
| * level of the activated method, has been violated. |
| * When Commons Math throws an {@code IllegalArgumentException}, it is |
| * usually the consequence of checking the actual parameters passed to |
| * the method. |
| */ |
| T value(T x); |
| } |