

Java example source code file (TestProblem2.java)
The TestProblem2.java Java example source code/* * 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/LICENSE2.0 * * 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.math3.ode; import org.apache.commons.math3.util.FastMath; /** * This class is used in the junit tests for the ODE integrators. * <p>This specific problem is the following differential equation : * <pre> * y' = t^3  t y * </pre> * with the initial condition y (0) = 0. The solution of this equation * is the following function : * <pre> * y (t) = t^2 + 2 (exp ( t^2 / 2)  1) * </pre> * </p> */ public class TestProblem2 extends TestProblemAbstract { /** theoretical state */ private double[] y; /** * Simple constructor. */ public TestProblem2() { super(); double[] y0 = { 0.0 }; setInitialConditions(0.0, y0); setFinalConditions(1.0); double[] errorScale = { 1.0 }; setErrorScale(errorScale); y = new double[y0.length]; } @Override public void doComputeDerivatives(double t, double[] y, double[] yDot) { // compute the derivatives for (int i = 0; i < getDimension(); ++i) yDot[i] = t * (t * t  y[i]); } @Override public double[] computeTheoreticalState(double t) { double t2 = t * t; double c = t2 + 2 * (FastMath.exp (0.5 * t2)  1); for (int i = 0; i < getDimension(); ++i) { y[i] = c; } return y; } } Other Java examples (source code examples)Here is a short list of links related to this Java TestProblem2.java source code file: 
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