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 * http://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 package org.apache.commons.math.ode; 19 20 21 22 /** This interface represents a first order differential equations set. 23 * 24 * <p>This interface should be implemented by all real first order 25 * differential equation problems before they can be handled by the 26 * integrators {@link FirstOrderIntegrator#integrate} method.</p> 27 * 28 * <p>A first order differential equations problem, as seen by an 29 * integrator is the time derivative <code>dY/dt</code> of a state 30 * vector <code>Y</code>, both being one dimensional arrays. From the 31 * integrator point of view, this derivative depends only on the 32 * current time <code>t</code> and on the state vector 33 * <code>Y</code>.</p> 34 * 35 * <p>For real problems, the derivative depends also on parameters 36 * that do not belong to the state vector (dynamical model constants 37 * for example). These constants are completely outside of the scope 38 * of this interface, the classes that implement it are allowed to 39 * handle them as they want.</p> 40 * 41 * @see FirstOrderIntegrator 42 * @see FirstOrderConverter 43 * @see SecondOrderDifferentialEquations 44 * 45 * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 févr. 2011) $ 46 * @since 1.2 47 */ 48 49 public interface FirstOrderDifferentialEquations { 50 51 /** Get the dimension of the problem. 52 * @return dimension of the problem 53 */ getDimension()54 int getDimension(); 55 56 /** Get the current time derivative of the state vector. 57 * @param t current value of the independent <I>time</I> variable 58 * @param y array containing the current value of the state vector 59 * @param yDot placeholder array where to put the time derivative of the state vector 60 * @throws DerivativeException this user-defined exception should be used if an error is 61 * is triggered by user code 62 */ computeDerivatives(double t, double[] y, double[] yDot)63 void computeDerivatives(double t, double[] y, double[] yDot) 64 throws DerivativeException; 65 66 } 67