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 /** This interface represents a first order differential equations set. 21 * 22 * <p>This interface should be implemented by all real first order 23 * differential equation problems before they can be handled by the 24 * integrators {@link FirstOrderIntegrator#integrate} method.</p> 25 * 26 * <p>A first order differential equations problem, as seen by an 27 * integrator is the time derivative <code>dY/dt</code> of a state 28 * vector <code>Y</code>, both being one dimensional arrays. From the 29 * integrator point of view, this derivative depends only on the 30 * current time <code>t</code> and on the state vector 31 * <code>Y</code>.</p> 32 * 33 * <p>For real problems, the derivative depends also on parameters 34 * that do not belong to the state vector (dynamical model constants 35 * for example). These constants are completely outside of the scope 36 * of this interface, the classes that implement it are allowed to 37 * handle them as they want.</p> 38 * 39 * @see FirstOrderIntegrator 40 * @see FirstOrderConverter 41 * @see SecondOrderDifferentialEquations 42 * 43 * @version $Revision: 620312 $ $Date: 2008-02-10 12:28:59 -0700 (Sun, 10 Feb 2008) $ 44 * @since 1.2 45 */ 46 47 public interface FirstOrderDifferentialEquations { 48 49 /** Get the dimension of the problem. 50 * @return dimension of the problem 51 */ 52 public int getDimension(); 53 54 /** Get the current time derivative of the state vector. 55 * @param t current value of the independent <I>time</I> variable 56 * @param y array containing the current value of the state vector 57 * @param yDot placeholder array where to put the time derivative of the state vector 58 * @throws DerivativeException this exception is propagated to the caller if the 59 * underlying user function triggers one 60 */ 61 public void computeDerivatives(double t, double[] y, double[] yDot) 62 throws DerivativeException; 63 64 }