| /* |
| * 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.ode.events; |
| |
| import org.apache.commons.math4.legacy.core.jdkmath.AccurateMath; |
| import org.apache.commons.numbers.core.Precision; |
| |
| |
| /** Transformer for {@link EventHandler#g(double, double[]) g functions}. |
| * @see EventFilter |
| * @see FilterType |
| * @since 3.2 |
| */ |
| enum Transformer { |
| |
| /** Transformer computing transformed = 0. |
| * <p> |
| * This transformer is used when we initialize the filter, until we get at |
| * least one non-zero value to select the proper transformer. |
| * </p> |
| */ |
| UNINITIALIZED { |
| /** {@inheritDoc} */ |
| @Override |
| protected double transformed(final double g) { |
| return 0; |
| } |
| }, |
| |
| /** Transformer computing transformed = g. |
| * <p> |
| * When this transformer is applied, the roots of the original function |
| * are preserved, with the same {@code increasing/decreasing} status. |
| * </p> |
| */ |
| PLUS { |
| /** {@inheritDoc} */ |
| @Override |
| protected double transformed(final double g) { |
| return g; |
| } |
| }, |
| |
| /** Transformer computing transformed = -g. |
| * <p> |
| * When this transformer is applied, the roots of the original function |
| * are preserved, with reversed {@code increasing/decreasing} status. |
| * </p> |
| */ |
| MINUS { |
| /** {@inheritDoc} */ |
| @Override |
| protected double transformed(final double g) { |
| return -g; |
| } |
| }, |
| |
| /** Transformer computing transformed = min(-{@link Precision#SAFE_MIN}, -g, +g). |
| * <p> |
| * When this transformer is applied, the transformed function is |
| * guaranteed to be always strictly negative (i.e. there are no roots). |
| * </p> |
| */ |
| MIN { |
| /** {@inheritDoc} */ |
| @Override |
| protected double transformed(final double g) { |
| return AccurateMath.min(-Precision.SAFE_MIN, AccurateMath.min(-g, +g)); |
| } |
| }, |
| |
| /** Transformer computing transformed = max(+{@link Precision#SAFE_MIN}, -g, +g). |
| * <p> |
| * When this transformer is applied, the transformed function is |
| * guaranteed to be always strictly positive (i.e. there are no roots). |
| * </p> |
| */ |
| MAX { |
| /** {@inheritDoc} */ |
| @Override |
| protected double transformed(final double g) { |
| return AccurateMath.max(+Precision.SAFE_MIN, AccurateMath.max(-g, +g)); |
| } |
| }; |
| |
| /** Transform value of function g. |
| * @param g raw value of function g |
| * @return transformed value of function g |
| */ |
| protected abstract double transformed(double g); |
| |
| } |